List of Papers Presented - INFLIBNETshodhganga.inflibnet.ac.in/bitstream/10603/24634/6/15...List of Papers Presented 1. Deepak Pathania, Sarita and B.S. Rathore , Synthesis, Characterization

List of Papers Presented

1. Deepak Pathania, Sarita and B.S. Rathore, Synthesis, Characterization and

Photocatalytic Application of CdS Nanoparticles, presented in International

Conference of chemists, held on 11-15th June, 2011 at Bangkok.

2. Deepak Pathania, Sarita, Virender Partap Singh, Sumita Sood and B.S.

Rathore, Studies on antibacterial properties of Cadmium sulphide and

Cadmium Oxide nanoparticles prepared by simple method, Presented,

Abstract No. P -11, National Conference on Recent trends on Materials

Sciences, to be held in Jay Pee University, Solan, H.P, on October 8-10, 2011.

3. Deepak Pathania, Sarita, Gaurav Sharma and B.S. Rathore, Photocatalytic

application and antibacterial properties of CuS nanoparticles, Presented,

National Symposium on Chemistry Innovations for Human Well Being

(CIHW 201)], be held in the Department of Chemistry, Himachal Pradesh

University, Shimla , HP, on October 21 – 22, 2011.

4. Deepak Pathania, Gaurav Sharma and B.S. Rathore, Study on Preparation

and Characterizationof Nano Composite Ion Exchanger: Pectin Stannic (IV)

Tungstophosphate, Presentated, International conference in innovations in

chemistry for sustainable Development, Panjab University on December 3-5,

2011.

5. Deepak Pathania, and B.S. Rathore, Antibacterial and Photocatalytic

Activities of Copper Sulphide Nanoparticles Prepared using Bovine Serum

Albumin as Capping Agent, Presentated, International Conference on

Frontiers of Nano Science, Nanotechnology and Their Applications, PU,

Chandigarh, Feb. 15-18, 2012.

6. Deepak Pathania, Gaurav Sharma and B.S. Rathore, Study on Preparation

and Characterizationof Nano Composite Ion Exchanger: Pectin Stannic (IV)

Tungstophosphate, Presented, International conference in innovations in

chemistry for sustainable Development, Panjab University on December 3-5,

2011.

7. Deepak Pathania, and B.S. Rathore, Antibacterial and Photocatalytic

Activities of Copper Sulphide Nanoparticles Prepared using Bovine Serum

Albumin as Capping Agent, Presented, International Conference on Frontiers

of NanoScience, Nanotechnology and Their Applications, PU, Chandigarh,

Feb. 15-18, 2012.

8. Deepak Pathania, B.S. Rathore, Pardeep Singh and Gaurav Sharma, Cerium

(IV) iodate ion exchanger: synthesis, characterization and application,

Presented in the "4th National Seminar on Chemistry: An Inter Disciplinary

Science-2012" (NSCIDS-2012) to held at Department of Chemistry, Panjabi

University, Patiala, February 15-16, 2012.

9. Deepak Pathania, B.S. Rathore, and Gaurav Sharma Synthesis

characterization and thermal stability of hybrid ion exchanger: Its antibacterial

activity, Presented, National Conference on Material Science, Application in

Energy and Environment, be held in Department of Chemistry DAV College,

Jalandhar, Punjab, 2-3 March, 2012.

10. Deepak Pathania and B.S Rathore, Synthesis and Characterization of pectin

based cerium (1V) tungstate hybrid ion exchanger, Presented, National

Conference on Global challenges: New Frontiers in Chemical Sciences,

Department of Chemistry, KU, Kurukshetra, Sept. 22-24, 2012, OT-39.

11. Deepak Pathania, Pardeep Singh and B.S. Rathore, Cellulose acetate

zirconium (IV) phosphate nanocomposite with ion exchange capacity and

enhanced photocatalytic activity, accepted for presentation, International

Conference on Recent Advances in Chemical Sciences, Department of

Chemistry, held on Arya P.G. College, Panipat, Haryana, on February 24 – 26,

2013.

12. Bhim Singh Rathore, Gaurav Sharma and Deepak Pathania, Photocatalytic

degradation of methylene blue using nanocomposite material under solar light,

Presented, Recent Advances in Chemical and Environmental Sciences, Held in

MM Modi College Patiala, Punjab on Nov. 13-14, 2013 (Abstract No. 28).

13. Deepak Pathania, Bhim Singh Rathore and Gaurav Sharma, Gaur gum based

cerium (IV) tungstate nanocomposite materials for adsorptional removal of

MB dye from water system, Presented, 3rdNtional Conference on Advanved

Materials and Radiation Physics, Held in Sant Longowal Institute of

Engineering & Technology on Nov. 22-23, 2013 (Abstract No. AM (P) 08).

14. Deepak Pathania, Gaurav Sharma and Bhim Singh Rathore, Synthesis and

characterization of polyaniline zirconium (IV) silicophosphate nanocomposite

for waste water treatment, National seminar on frontiers in polymer science-II

(FPS-2013) December 12-13, 2013 (PP-61).

15. Bhim Singh Rathore, Deepak Pathania, and Gaurav Sharma, Synthesis,

characterization and application of cellulose acetate-tin (IV) phosphate

nanocomposite ion exchanger, National seminar on recent trends in materials,

energy and environment, Presented, Sri Sai University Palampur, Kangra,

Himachal Pradesh on 18th Jan., 2014 (PP-8).

16. Deepak Pathania, B.S. Rathore, Divya Gupta and Gaurav Sharma, Synthesis

and characterization of pectin cadmium sulfide nanocomposite: Photocatalytic

and antibacterial activity, Abstract 341, Accepted for presentation in National

Conference on 06-07 March 2014 at DAV College Jalandhar, Punjab.

17. Deepak Pathania, B.S. Rathore and G. Sharma, Synthesis and characterization

of cellulose acetate based tin (IV) molybdate nanocomposite cation exchanger,

Presented, Advances in Chemical & Environmental Sciences from February

27-28, 2014 at Arya PG College, Panipat, Haryana.

List of Publications

1. Bhim Singh Rathore and Deepak Pathania, Styrene-tin (IV) phosphate

nanocomposite for photocatalytic degradation of organic dye in presence of visible

light, Journal of Alloys and Compounds, 606, 105-111, 2014.

2. Bhim Singh Rathore, Gaurav Sharma, Deepak Pathania and V. K. Gupta Synthesis,

characterization and antibacterial activity of cellulose acetate-tin (IV) phosphate

nanocomposite, Carbohydrate Polymers, 103, 221-227, 2014.

3. B.S. Rathore, Gaurav Sharma and Deepak Pathania, Photocatalytic activity of

cellulose acetate-tin (IV) molybdate nanocomposite in solar light, SMC Bulletin,

4(3), 11-16, 2013.

4. V. K. Gupta, Deepak Pathania, Pardeep Singh, Amit Kumar and B.S.Rathore,

Adsorptional removal of methylene blue by gaur gum-cerium (IV) tungstate hybrid

cationic exchanger, Carbohydrate Polymer, 101, 684-691, 2014.

5. V. K. Gupta, Deepak Pathania, Pardeep Singh, B.S.Rathore, Paryanka Chauhan,

Cellulose acetate-zirconium (IV) phosphate nanocomposite ion exchanger with

photocatalytic activity, Carbohydrate Polymer, 95, 2013, 434-440.

6. Deepak Pathania, Sarita and B.S. Rathore, Synthesis, Characterization and

photocatalytic application of Bovine Serum Albumin capped CdS nanoparticles, The

Chalcogenide Letters, Vol. 8, No. 6, June 2011, p. 396 - 404.

7. Bhim Singh Rathore, Gaurav Sharma, Deepak Pathania, Novel material for binary

separation of metal ions and antibacterial activities: Cellulose acetate-tin (IV)

molybdate nanocomposite ion exchanger, Journal of Industrial and Engineering

Chemistry, Under Review, 2014.

8. Gaurav Sharma, Deepak Pathania, Amit Kumar, B.S. Rathore, Susheel Kalia,

Synergistic adsorptional-photocatalytic remediation of malachite green and

methylene blue by polyanilineZr(IV) selenotungstophosphatenanocomposite ion

exchanger, Applied Catalysis A, Communicated,2014.

Carbohydrate Polymers 95 (2013) 434– 440

Contents lists available at SciVerse ScienceDirect

Carbohydrate Polymers

jou rn al hom epa ge: www.elsev ier .com/ locate /carbpol

Cellulose acetate–zirconium (IV) phosphate nano-composite withenhanced photo-catalytic activity

Vinod Kumar Guptaa,b,∗, Deepak Pathaniac, Pardeep Singhc, Bhim Singh Rathorec,Priyanka Chauhanc

a Department of Chemistry, Indian Institute of Technology Rookree, Roorkee 247667, Indiab Chemistry Department, King Fahd University of Petroleum & Minerals, Dhahran 31261, Saudi Arabiac Department of Chemistry, Shoolini University, Solan 173212, Himachal Pradesh, India

a r t i c l e i n f o

Article history:Received 11 January 2013Received in revised form 7 February 2013Accepted 21 February 2013Available online xxx

Keywords:Cellulose acetateZirconium (IV) phosphateNanocompositeIon exchange propertyPhotocatalysis

a b s t r a c t

Cellulose acetate–zirconium (IV) phosphate nanocomposite (CA/ZPNC) was synthesized by sol–gel tech-nique at pH 0–1 and was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM),energy dispersive X-ray (EDX) spectroscopy, Fourier infrared spectroscopy (FTIR) and thermal analysis(TGA/DTA/DSC). Ion exchange capacity, pH titration, elution concentration, elution behaviour, thermalstability and distribution coefficient were investigated to explore ion exchange behaviour of CA/ZPNC.The nanocomposite showed an ion-exchange capacity of 1.4 mequiv. g−1 for Na+ and was highly selectivefor Pb2+ and Zn2+ over many other metal ions. The photocatalytic activity of the CA/ZPNC was exploredfor degradation of a model Congo red dye from aqueous phase. 90% of dye was removed in 60 min ofirradiation. Simultaneous adsorption and photocatalysis had synergetic effect on dye degradation.

© 2013 Elsevier Ltd. All rights reserved.

1. Introduction

Several industries such as textile, paper, paint, and dyestuffsconsume large quantity of water and utilize chemicals and dyesto form products; as a consequence, several toxic metals andchemicals are discharged continuously into the water bodies. Thedischarged industrial pollutants deteriorate the water quality andmay cause adverse effect on human health due to their toxic, muta-genic and carcinogenic nature (Gupta, Rastogi, & Nayak, 2010;Huang & Chen, 2009; Korbahti, Artut, Gecgel, & Ozer, 2011; Zhaoet al., 2012). Congo red – an anionic dye has been known to causean allergic reaction and is known to be metabolized to benzidinewhich in turn is a human carcinogen (Chatterjee, Lee, Lee, & Woo,2009).

Wastewaters containing synthetic dyes and toxic metal ions aredifficult to treat, since they are recalcitrant, resistant to biologicaloxidation/reduction, and are stable to oxidizing agents. The con-ventional methods such as coagulation, flocculation, precipitation,membrane separation, solvent extraction, adsorption and reverseosmosis are not able to treat industrial effluent effectively (Vilhera,Goncalves, & Mota, 2004). In practice, no single process providesadequate treatment and a combination of different processes is

∗ Corresponding author at: Department of Chemistry, Indian Institute of Technol-ogy Rookree, Roorkee 247667, India. Tel.: +91 1332285801; fax: +91 1332286202.

E-mail addresses: [email protected], [email protected] (V.K. Gupta).

often used to improve the water quality in a greener and moreeconomic way.

It is now well documented that low cost bio-adsorbent basedadsorption processes are effective and economic methods forwastewater remediation (Gupta, Ali, & Saini, 2007; Gupta, Jain,& Varshney, 2007; Gupta, Agarwal, & Saleh, 2011; Gupta, Mittal,Malviya, & Mittal, 2009; Jain, Gupta, Bhatnagar, & Suhas, 2003;Mittal, Mittal, Malviya, & Gupta, 2009; Mittal, Mittal, Malviya, &Gupta, 2010; Mittal, Gupta, Malviya, & Mittal, 2008; Mittal, Mittal,Malviya, Kaur, & Gupta, 2010; Gupta, Gupta, Rastogi, Nayak, &Agarwal, 2011). A large variety of non-conventional bio-adsorbentshave been employed to remove metal ions and dyes from aque-ous phase. Much attention has been focused on fungal or bacterialbiomass and biopolymers that are harmless and are ubiquitouslyavailable in nature (Constantin et al., 2013; Gupta et al., 2010;Oei, Ibrahim, Wang, & Ang, 2009; Yang et al., 2012). However, lackof stability, intricacies in separation from aqueous phase and lowrecovery after desorption are the major limitations for large scaleapplication of bio-absorbents (Gupta et al., 2010).

In order to meet the stringent environmental regulation, thephotocatalytic reactions have advantages over classical and non-conventional methods for dye degradation due to their simplicityand rapid degradation based on hydroxyl radical formation. Nowa-days, hybrid organic–inorganic nanocomposites are materials ofchoice because of their multifunctionality due to a combinationof different compounds incorporated. Recent examples can befound in the range of TiO2, BiOCl, Fe2O3, CuS and ZnO based

0144-8617/$ – see front matter © 2013 Elsevier Ltd. All rights reserved.http://dx.doi.org/10.1016/j.carbpol.2013.02.045

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V.K. Gupta et al. / Carbohydrate Polymers 95 (2013) 434– 440 435

nanocomposites (Dong, Sun, Min, Wu, & Lee, 2012; Liu, Sun, Liu,& Wang, 2013; Virkutyte, Jegatheesan, & Varma, 2012). Primarily,adsorption of pollutants on the catalyst surface is a pre-requisitefor the effective photo-degradation process (Qourzal, Tamimi,Assabbane, & Ait-Ichou, 2005). However, little work has been doneto develop hybrid nano-bio-composite material with high adsorp-tion capacity and enhanced photocatalytic activity (Gupta, Ali,Saleh, Nayak, & Agarwal, 2012).

Recently, cellulose based nanocomposites have drawn consid-erable attention because of their low cost, high-volume application,easy processability, renewable nature and possibility of recycling(Ali, 2012). There are several research efforts reporting the cellu-lose composite with carbon nanotubes, lignin and lumiscent CdS(Nevarez et al., 2011; Park & Kadla, 2012; Yang et al., 2012). Fitz-Binder and Bechtold (2012) investigated the adsorption of Ca2+ ionson regenerated cellulose fibres such as lyocell, viscous and modelfibres. Zirconium phosphate is an inorganic ion exchanger of theclass of tetravalent metal acid (TMA) salts. It has been recentlydemonstrated as an excellent sorbent for heavy metals due to itshigh selectivity, high thermal stability and absolute insolubility inwater. Thakkar and Chudasama (2009) studied the exchange prop-erties of zirconium titanium phosphate (ZTP) for the separation ofCu2+, Ni2+, Zn2+, Co2+, Cd2+, Hg2+, Pb2+, Bi2+, La3+, Ce2+, Th4+, andUO2

2+. Kubli et al. (2012) synthesized zirconium phosphate basedmicroporous ion exchanger that can discriminate between CO2 andCH4. Mishima, Matsuda, and Miyake (2007) studied the photocat-alytic efficacy of Zr2ON2 yielding H2 and O2 by water reduction.However major disadvantage of synthetic inorganic ion exchang-ers is the difficulty in preparing granulated materials with sufficientstrength and suitable mechanical properties for column operations.

Until now, as far as, we could ascertain, no data is avail-able concerning the preparation of cellulose acetate–zirconium(IV) phosphate nanocomposite as a visible light active photocat-alyst. The objective of the present work is to prepare celluloseacetate–zirconium (IV) phosphate nanocomposite (CA/ZPNC) bysol–gel transformations. The ion exchange behaviour of CA/ZPNCwill be explored for the adsorption of different metal ions. The pho-tocatalytic activity of CA/ZPNC was also utilized for the degradationof Congo red (CR) dye. It was characterized by scanning elec-tron transmission (SEM), transmission electron microscopy (TEM),energy dispersive X-ray (EDX), thermo gravimetric and differentialtemperature analysis, X-ray diffraction (XRD) and Fourier trans-form infrared (FTIR) and ultraviolet–visible (UV–Vis) spectroscopyand subjected to ion-exchanger photocatalytic activity study.

2. Experimental

2.1. Chemicals and materials

The main reagents used were zirconium oxychloride,orthophosphoric acid, cellulose acetate and were purchasedfrom Sigma–Aldrich, India. All reagents were used without furtherpurification. The Congo red dye was obtained from S.D. Fine India.All other chemicals and reagents used were of analytical reagentgrade. All the solutions were prepared in double distilled water.

2.2. Preparation of cellulose acetate Zirconium (IV) phosphate(CA/ZPNC)

In the present work, cellulose acetate based nanocompositewas synthesized using simple and ambient sol gel method (Fig. 1).Firstly, solutions of 0.1 M orthophosphoric acid and 0.1 M zirconium(IV) oxychloride were gradually mixed with continuous stirring atpH 2. After complete addition, the mixture was stirred for 30 minto obtain zirconium (IV) phosphate (ZP) precipitates. In the next

step, cellulose acetate (CA) gel was prepared in concentrated formicacid and added to zirconium (IV) phosphate solution with contin-uous stirring for 4 h The resultant mixture was allowed to standfor 24 h with occasional shaking in the mother liquor for diges-tion. The precipitates were separated by filtration and washedwith demineralised water several times to remove excess of thereagents. The precipitates were equilibrated with 0.1 M HNO3 solu-tion for 24 h to convert into H+ form. It was then filtered and washedwith demineralised water to remove any excess acid and finallydried in an oven at 80 ◦C.

2.3. Instrumentation

Thermal analysis of CA/ZPNC was performed on thermo gravi-metric analyzer (NETZSCH TG 209 F1). X-ray diffraction datawere recorded using X-ray diffractometer (Phillips, Holland, modelPW 1148/89). Fourier transformer infrared (FTIR) spectra wereobtained using Perkin Elmer spectrometer (Spectrum 400, USA).The surface morphology of the nanocomposite was studied usingscanning electron microscope (SEM Quant-250, model 9393). Themicrostructure was analyzed by transmission electron microscopy(TEM) using Tecnai 20 G2 (Plate/CCD Camera). The concentrationof dye was determined using Systronics 117UV–visible spectropho-tometer.

2.4. Ion exchange activity of CA/ZPNC

2.4.1. Ion exchange capacityThe ion exchange capacity of CA/ZPNC was determined by

standard column method. In this process, 0.5 g (dry mass) ofCA/ZPNC in H+ form was placed in a glass tube of 1 cm internal diam-eter at glass wool supported at the bottom. The column containingCA/ZPNC was washed with double distilled water to remove excessacid. 0.1 M NaCl (250 mL) solution was used to elute H+ from theCA/ZPNC. The flow rate of eluent was maintained at 0.5 mL min−1.The collected effluent was titrated against a standard alkali solu-tion. The hydrogen ions released were calculated using the formulaas discussed earlier (Siddiqui & Khan, 2007):

IEC = N × V

Wmg/g (1)

where IEC is ion exchange capacity. N and V (mL) are normal-ity and volume of NaOH, respectively. W (mg) is the amount ofCA/ZPNC.Thermal stability

0.5 g sample of CA/ZPNC in H+ form was heated at differenttemperatures in muffle furnace for 1 h. The sample was weighedand ion exchange capacity was determined after cooling to roomtemperature.

2.4.2. Effect of eluent concentrationThe optimum concentration for complete elution of H+ ions from

CA/ZPNC was studied. 250 mL of NaNO3 solution of different con-centration was passed through the columns, containing 0.5 g of theexchanger in H+ form with a flow rate of 0.5 mL min−1. The collectedeluents were titrated against 0.1 M NaOH in order to determine theeluted H+ ions.

2.4.3. Elution behaviourNaNO3 solution (1 M) was passed through a column containing

0.5 g of CA/ZPNC for complete elution of H+. Effluent was collectedin 10 mL fraction at a flow rate of 0.5 mL min−1. Each fraction of10.0 mL was titrated with 0.1 M NaOH solution.

2.4.4. pH-titrationpH-titration studies were performed using Topp and Pepper

method (Gupta, Pathania, Agarwal, & Singh, 2012). In typical

436 V.K. Gupta et al. / Carbohydrate Polymers 95 (2013) 434– 440

Fig. 1. Schematic diagram of preparation of cellulose acetate–zirconium acetate nanocomposite.

method, 0.5 g of CA/ZPNC in H+ form was placed in each of 250 mLconical flasks containing equimolar solutions of alkali metal chlo-rides and their hydroxide in different volume ratios. Total volumewas kept at 50 mL to make the ionic strength constant. pH of thesolution was recorded every 24 h until equilibrium was attained in10 days.

2.4.5. Distribution studiesDistribution coefficients of different metal ions such as Pb2+,

Zn2+, Th2+, Cu2+, Ni2+, Cd2+, Mg2+ were determined in aqueous solu-tion using batch process. 0.5 g of CA/ZPNC in H+ form and 20 mLof different metal nitrate solutions were continuously shaken for24 h at 25 ◦C. Metal ion concentration was determined by titratingagainst EDTA solution. Kd values (mL/g) were determined using fol-lowing formula (Inamuddin, Khan, Siddiqui, & Khan, 2007; Siddiqui& Khan, 2007):

Kd = I − F

F× V

M(2)

where I and F indicate initial and final concentration of metal ionin solution. V and M denotes final volume of the solution (mL)and amount of ion exchanger (g), respectively.Photocatalytic andadsorption experiment

The photocatalytic experiment was carried out in a slurrytype batch reactor (Gupta et al., 2012a). Double walled pyrexvessel was surrounded by thermostatic water circulation arrange-ment to keep temperature in the range of 30 ± 0.3 ◦C. Duringadsorption experiments, slurry composed of dye solution andCA/ZPNC (S-1) suspension was stirred magnetically and placedin dark to attain equilibrium. In case of photocatalytic studies,suspension composed of dye and catalyst was stirred for 10 min.Then suspension was exposed to natural solar light (solar inten-sity = 56 × 104 ± 250 lx) with continuous stirring. At specific timeintervals, aliquot (3 mL) was withdrawn and centrifuged for 2 minto remove catalyst particles form aliquot. The dye concentration

was determined at 490 nm spectrophotometrically. The decolouri-sation efficiency of dye was calculated using following equation:

%removal efficiency = C0 − Ct

C0× 100 (3)

where C0 is the initial and Ct is instant concentration of Congo red.The kinetics of dye degradation was described by pseudo first

order kinetics. The rate constant (kobs) was calculated using thefollowing equation:

kobs = 2.303 × slope (4)

where the slope was obtained from the plot of ln(c) versus t.

3. Results and discussion

3.1. Characterization of CA/ZPNC

Scanning electron microscopy (SEM) images of CA/ZPNC at dif-ferent magnifications are shown in Fig. 2(a and b) which exhibitsrough surface with different sized particles to form microsphere.As seen in Fig. 2(c and d), TEM images signify homogeneous distri-bution of CA and ZP particles in nanocomposite. The darker portionrepresents CA wrapped in ZP while the grey part corresponds toCA in polymeric backbone. These images clearly indicate CA/ZPNCformation in the range of 50 nm.

Fig. 3(a) represents X-ray diffraction pattern of CA, ZP andCA/ZPNC. The broader diffraction peaks between 10◦ and 23◦ clearlyindicates the amorphous nature of CA. The small intensity diffrac-tion peaks near 20◦ are the characteristic peaks of ZP (Liu, Ma, Gan,Li, & Wang, 2012; Jo, Shin, & Wang, 2011). In case of ZPNC, emer-gence of low intensity broader peaks of ZP indicates the amorphousnature of nanocomposite.

EDX studies of CA/ZPNC are shown in Fig. 3(b). Zr, P, C and Oelements are present in weight percentage of 30.27, 13.51, 12.55and 43.67, respectively.


Fig. 2. SEM and TEM images of CA/ZPNC. Inset is SEM image of ZP.

FTIR spectrum of CA/ZPNC (Fig. 3(c)) shows a broad peak at3423 cm−1 which may be assigned to water molecule. A sharp peakat 1631 cm−1 represents free water molecule (water of crystalliza-tion) and strongly bonded OH group in the matrix. The peak at1039 cm−1 may be due to occurrence of PO4

3−, HPO42− and H2PO4

−

(Siddiqui & Khan, 2007). Absorption band at 1734 cm−1, corre-sponds to the carbonyl of ester group in cellulose acetate. The peaksat 520 and 610 cm−1are due to the superposition of metal–oxygenstretching vibrations confirming binding between cellulose acetateand Zr (IV) phosphate. A sharp peak at 1389 cm−1 is assigned tohydroxyl groups vibration (Siddiqui & Khan, 2007).

It is seen from TGA curve (Fig. 4) that the initial loss of 16.7%(150.3 ◦C) is due to the removal of water from the nanocomposite

(Inamuddin et al., 2007). Slow weight loss (11.7%) between 150 and390 ◦C depicts condensation of phosphate group to pyrophosphategroups. Further weight loss up to 600 ◦C indicates complete decom-position of the organic part of the material. DTA curve illustratessmall exothermic peaks at 53 ◦C, 103 ◦C, 215 ◦C, 451 ◦C and 550 ◦Cconfirming structural transformation in CA/ZPNC (Inamuddin et al.,2007; Siddiqui & Khan, 2007).

3.2. Ion exchange behaviour of CA/ZPNC

Different samples of new and novel organic-inorganic nanocom-posite were prepared by the sol–gel mixing of inorganic matrices ofZr (IV) phosphate and cellulose acetate in different ratios (Table 1).

Fig. 3. XRD, EDX and FTIR spectra of CA/ZPNC.


Temp Cel

700.0600.0500.0400.0300.0200.0100 .0

DT

A u

V

50.00

40.00

30.00

20.00

10.00

0.00

-10.00

-20 .00

TG

%

140 .0

120 .0

100 .0

80.0

60.0

40.0

20.0

15.00

10.00

5.00

0.00

-5.00

-10.00

53.4Cel-5.65uV

103.7Cel-3.18uV

215.7Cel-1.78uV

550.4Cel-9.22uV

451.1Cel-7.84uV

51.2Cel0.16mg/min

378.5Cel0.03mg/min

33.9Cel131.7%

150.3Cel115.0% 390.2Cel

103.3%571.0Cel69.0%

16.7%

11.7%

34.3%

Fig. 4. TGA and DTA curves of CA/ZPNC.

Sample S-1 of CA/ZPNC possessed a better Na+ ion-exchange capac-ity (1.4 mequiv. g−1) as compared to their inorganic counterpart(sample S-5) (0.5 mequiv. g−1) and was thus used in the furtherstudies of characterization and testing. The improvement in theexchange capacity of nanocomposite exchanger may be due to thebinding of organic polymeric material with inorganic moiety. Thisnanocomposite exchanger showed a good reproducible character-istic which is evident from the fact that the material obtained fromvarious batches under identical conditions did not show any appre-ciable change in the percentage of yield and ion exchange capacity.

Table 2 depicts the effect of temperature on ion exchangecapacity of nanocomposite. Ion exchange capacity decreased withincrease in temperature. The results revealed that CA/ZPNC pos-sessed high thermal stability as the sample retained about 30% ofthe initial ion exchange capacity even after heating up to 400 ◦C.

The effect of eluent concentration on ion exchange capacity ofCA/ZPNC was investigated. The rate of elution was governed bythe concentration of the eluent and this behaviour is typical of thecomposite ion exchange materials (Inamuddin et al., 2007; Siddiqui& Khan, 2007). Optimum concentration of NaNO3 as eluent forCA/ZPNC was found to be 1 M for maximum release of H+ ions.

The elution behaviour of CA/ZPNC confirmed that all theexchangeable H+ ions were eluted out at 150 mL of the effluent.

pH titration behaviour at equilibrium conditions for CA/ZPNCwith NaOH–NaCl system illustrated the mono functional nature ofnanocomposite. The CA/ZPNC behaved as a strong cation exchangeras indicated by the low pH of the solution when no OH− ions wereadded.

The distribution studies showed that CA/ZPNC exchanger wasfound to be highly selective for Pb2+ and Zn2+ as compared to theother metal ions. Thus the composite can be utilized for separa-tion and determination of lead and zinc ions from waste effluents(Siddiqui & Khan, 2007).

Based upon Kd values, the order of selectivity for different metalion was found as: Pb2+ (Kd = 220 mL/g) > Zn2+ (Kd = 200 mL/g) > Th2+

(Kd = 92 mL/g) > Cu2+ (Kd = 62.7 mL/g) > Ni2+ (Kd = 62.0 mL/g) > Cd2+

(Kd = 60.16 mL/g) > Mg2+ (Kd = 40.5 mL/g). The distribution studiesshowed that CA/ZPNC exchanger was highly selective for Pb2+ andZn2+ ions as compared to other metal ions.

3.3. Photocatalytic activity of CA/ZPNC

The photocatalytic activity of CA/ZPNC, ZP (S-1) was evalu-ated for the degradation of Congo red (CR) dye in the presenceof solar light (Fig. 5(a)). The decrease in CR concentration wasmore with CA/ZPNC which shows that the composite has higheractivity as compared to CA and ZP. The direct photolysis inabsence of photocatalyst did not show any significant effect onCR degradation. However, CR degradation increased appreciablyin the presence of both sunlight and catalyst (CA/ZPNC). WhenCA/ZPNC was irradiated with solar light, the charge separationproduced electron–hole pair (h−

vb/e+CB). The conduction band elec-

trons were transferred to catalyst surface. The conduction bandelectrons reduced the O2 and formed the hydroxyl radicals. Thevalance band holes acted as the electron sink and reacted withH+/H2O at the catalyst surface to form OH radicals (Sillanppa,

Table 1Synthesis of different samples of cellulose acetate Zr (IV) phosphate nanocomposite (CA/ZPNC) exchanger.

Sample no. Mixing volume rations of reagents (v/v) Total volume(mL)

pH Colour ofprecipitates

Yield (g) IEC for Na+

(meq g−1)Cellulose acetate informic acid (%w/v)

Zirconiumoxychloride (0.1 M)

Orthophosphoricacid (0.1 M)

S-1 1 100 50 175 1.0 White 1.91 1.4S-2 2 100 50 175 1.0 White 2.00 1.1S-3 3 100 50 175 1.0 White 3.10 0.56S-4 4 100 50 175 1.0 White 3.76 0.58S-5 0 100 50 175 1.0 White 3.00 0.5


Table 2Effect of temperature on ion exchange capacity of cellulose acetate Zr (IV) phosphate nanocomposite (CA/ZPNC) exchanger.

Heatingtemperature (◦C)

Weight beforeheating

Weight afterheating

Colour after heating IEC for Na+ ion(meq g−1)

Retention of ionexchange capacity

75 0.53 0.48 White 1.3 92.85100 0.53 0.47 White 1.28 91.42200 0.53 0.41 Dark brown 0.82 58.57300 0.53 0.40 Brown 0.64 45.71400 0.53 0.35 Light brown 0.42 30.00

Fig. 5. Photocatalytic degradation (a) and adsorption removal (b) of CR dye under different systems. [CR] = 100 mg/100 mL, pH = 4, catalyst/adsorbent dose = 5 mg/100 mL,time = 60 min and solar intensity = 56 × 104 ± 250 lx.

Kurniawasn, & Lo, 2011). The highly oxidizing hydroxyl radicals(redox potential = 2.8 ev) caused the degradation of the CR dye. Asshown in Fig. 5(a), 90% of CR was removed in 60 min of irradiationinvolving pseudo-first-order rate constant (kobs = 0.0655 min−1).However, 40 and 20% of CR removal was observed in the caseof ZP (kobs = 0.0315 min−1) and CA (kobs = 0.015 min−1), respec-tively. In similar studies, Sun, Wang, Sun, and Dong (2009)investigated hydroxyl radical induced degradation of CR usingpseudo-first-order kinetics (kobs = 0.0355 min−1). Zhu et al. (2009)reported pseudo-first-order rate constant, 0.011 min−1 at pH 6for photodegradation of CR. Adsorption plays a very crucial rolein the photodegradation process and occurs on the surface ofnanocomposite. The photodegradation of the dye depends on theconcentration of dye in both the bulk solution and on the catalystsurface. The real photodegradation can be explained on the basisof the decrease in the dye concentration both in bulk solution andon the catalyst surface (Zhang et al., 1998; Hu, Tang, Yu, & Wong,2003). The higher adsorption capacity of CA/ZPNC was due to thepresence of both cellulose acetate and ZP in the nanocomposite(Fig. 5(b), Xu, Cai, & Shea, 2007).

In the case of CA/ZPNC, the effect of adsorption in photodegra-dation of CR was studied under three reaction conditions. Thethree reaction conditions i.e., equilibrium adsorption in dark,equilibrium adsorption followed by photodegradation, and simul-taneous adsorption and degradation are denoted by CA/ZPNC/DA,CA/ZPNC/A − P and CA/ZPNC/A + P, respectively, unless, otherwisespecified (Fig. 6). In simultaneous adsorption and degradationprocess (A + P), 95% of the dye in bulk solution was degradedin 60 min under solar light while in dark adsorption (DA) only40% of dye was removed. During CA/ZPNC/A − P process, the

catalyst particles were highly covered by CR molecules. Such highcoverage by CR dye molecules might cut off the sunlight, resultingin lower degradation of CR. In case of simultaneous adsorptionand photocatalytic process, the instant amount of dye adsorbedontoCA/ZPNC at each time was not very high; thereby causingweak screening effect to sunlight and hence to provide adequateactive sites for the creation of valence- band holes and conductionband electrons (Gupta et al., 2012a; Xu et al., 2007). On the other

Fig. 6. CR degradation onto CA/ZPNC under different system: [CR] = 100 mg/100 mL,pH = 4, catalyst dose = 5 mg/100 mL, time = 60 min and solar inten-sity = 56 × 104 ± 250 lx.


hand, the adsorbed dye molecules could be degraded rapidlyduring simultaneous photocatalysis. This concurrent photodegra-dation increased the sunlight transmittance to catalyst surface andimproved the process efficiency.

4. Conclusion

In the present study, an ambient reaction condition methodwas developed to prepare cellulose acetate–zirconium (IV) phos-phate nanocomposite. Spectral analysis confirmed the high levelof CA and zirconium (IV) phosphate nanocomposite formation.CA/ZPNC was stable at high temperature exhibiting promising ionexchange capacity and photocatalytic activity. The ion exchangecapacity decreased with increase in temperature. CA/ZPNC behavedas strong cation exchanger, showing high selectivity to Pb2+. Congored dye was successfully degraded in CA/ZPNC/solar light system.The simultaneous adsorption and photocatalysis processes provedto be highly efficient for Congo red dye degradation.

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jo u r n al homep age: www.elsev ier .com/ locate /carbpol

Adsorptional removal of methylene blue by guar gum–cerium (IV)tungstate hybrid cationic exchanger

V.K. Guptaa,∗, Deepak Pathaniab, Pardeep Singhb, Amit Kumarb, B.S. Rathoreb

a Department of Chemistry, Indian Institute of Technology, Roorkee 247667, Indiab School of Chemistry, Shoolini University, Solan 173212, Himachal Pradesh, India


Article history:Received 15 August 2013Received in revised form21 September 2013Accepted 27 September 2013Available online xxx

Keywords:Hybrid ion exchangerCharacterizationMethylene blueAdsorptionKinetics

a b s t r a c t

Guar gum–cerium (IV) tungstate nanocomposite (GG/CTNC) cationic exchanger was synthesized usingsimple sol gel method. The GG/CTNC was characterized using X-ray diffraction (XRD), Fourier trans-mission infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and energy dispersive X-rayspectrophotometer (EDX). The XRD studies confirmed amorphous and fibrous in nature of GG/CTNC.The high percentage of oxygen in the nanocomposite material confirmed the functionality tungstate(WO4

−). The ion exchange capacity of GG/CTNC for Na+ ion was observed to be 1.30 mequiv g−1. Thehybrid exchanger was used as potential adsorbent for the removal of methylene blue (MB) from aque-ous system. The correlation coefficients value indicated a good fit of monolayer Langmuir model to theadsorption of methylene blue onto GG/CTNC. The adsorption kinetic study revealed that the adsorptionprocess followed the pseudo second order kinetic. The Gibbs free energy (�G) values confirmed thespontaneous nature of adsorption process.

© 2013 Elsevier Ltd. All rights reserved.

1. Introduction

The fast industrial development throughout world has sig-nificantly increased the production of wastewater from variousindustries such as, textile, paper, paint, and dyestuffs consume;as a consequence toxic synthetic dyes are discharged into waterbodies. The discharged dyes degrade the water quality and maycause adverse effect on human health due to toxic, mutagenicand carcinogenic nature (Gupta & Ali, 2008; Gupta, Agarwal, &Saleh, 2011; Gupta, Jain, & Varshney, 2007; Gupta, Mittal, Malviya,& Mittal, 2009; Gupta, Rastogi, & Nayak, 2010; Gupta, Pathania,Agarwal, & Singh, 2012; Mittal, Gupta, Malviya, & Mittal, 2008;Mittal, Mittal, Malviya, Kaur, & Gupta, 2010). The synthetic dyesare difficult to treat, since these are resistant to biological oxi-dation/reduction, and stable to oxidizing agents. The applicationof conventional methods like coagulation, flocculation, precipita-tion, membrane separation, solvent extraction and adsorption, doesnot treat industrial dye-effluent efficiently (Vilhera, Goncalves, &Mota, 2004). In practice, no single process provides adequate treat-ment and combination of different process has been often used toimprove the water quality in most greener and economic way. Itis now well recognized that bio-adsorbent are gaining importanceas effective and economic methods for wastewater remediation.

∗ Corresponding author. Fax: +91 1332273560.E-mail addresses: [email protected], [email protected] (V.K. Gupta),

[email protected] (D. Pathania).

A large number of non-conventional bio-adsorbents such as fun-gal or bacterial biomass or biopolymers have been employed toremove toxic metals and dyes from aqueous phase (Constantinet al., 2013; Zhao, Zeng, Li, et al., 2012a; Zhao, Zeng, Hu, et al.,2012b). The bio-adsorbent are low-cost, harmless and abundantlyavailable (Constantin et al., 2013; Yang et al., 2012). However,lower stability, difficulty in separation from aqueous phase and lowrecovery after desorption were the major limitations for large scaleapplicability of bio-absorbents (Gupta et al., 2011, 2012).

Organic–inorganic nanocomposite materials are of importancebecause of their multifunctionality owing to a combination of dif-ferent compounds incorporated. Recently, TiO2, BiOCl, Fe2O3, CuSand ZnO based bio-nanocomposites have been used for dyes andmetal removal from wastewater (Dong, Sun, Min, Wu, & Lee, 2012;Gupta et al., 2012; Huang & Chen, 2009; Virkutyte, Jegatheesan,& Varma, 2012). Nowadays, bio-material based nanocompositeshave drawn considerable attention because of their low-cost, easyprocessability, high-volume application, renewable nature andpossibility of recycling. There are several research efforts reportingthe bio-composite with carbon nanotubes, lignin and lumiscent CdS(Nevarez et al., 2011; Park & Kadla, 2012; Yang et al., 2012). Guaris a naturally occurring polysaccharide extracted from the beans ofthe guar gum plant. It is used as environmental-friendly thickenerto control visco-elasticity in food, personal care and oil recoveryindustries. Cerium (IV) derivates represent inorganic ion exchang-ers of tetravalent metal acid salts class. It has shown excellentadsorption ability for heavy metal due to its high selectivity, highthermal stability and absolute insolubility in water (Semischenko,





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Stepanenko, Gulina, & Tolstoi, 2011). Brigante et al. investigatedadsorptional behavior of cerium (IV) oxide the separation ofantibiotic minocyline (Brigante & Schulz, 2012). Sivashankar et al.synthesized cerium tailored carbon and studied its adsoptionalbehavior for fluoride removal from drinking water (Sivasankar,Murugesh, Rajkumar, & Darchen, 2013). Semischenko et al. pre-pared and investigated physico-chemical properties of cerium (IV)tungstate nanolayers (Semischenko et al., 2011). However majordisadvantage of synthetic inorganic ion exchangers is the difficultyin preparing granulated materials with high adsorption capac-ity for effective removal of organic pollutants from wastewater.Hybrid nanocomposites are recently the materials of interest dueto their multifunctionality involving the combination of differentcompounds.

To best of our knowledge, no data are available on the adsorptionactivity of guar gum–cerium (IV) tungstate (GG/CTNC) for methy-lene blue removal from aqueous phase. The present work dealswith sol-gel preparation of guar gum–cerium (IV) tungstate com-posite. The ion exchange behavior of GG/CTNC will be investigatedfor adsorption of different metal ions. The adsorptional activityof GG/CTNC was also utilized for the removal of methylene blue.GG/CTNC was characterized by scanning electron transmission(SEM), transmission electron microscopy (TEM), energy dispersiveX-ray (EDX) and X-ray diffraction (XRD) spectral techniques.

2. Experimental

2.1. Materials and methods

Ceric ammonium nitrate, sodium tungstate and methylene bluewere purchased from Sigma-Aldrich, India and used without fur-ther purification. Guar gum was obtained from Rama industries,India. All other chemicals and reagents used were of analyticalreagent grade. All the solutions were prepared in double distilledwater.

2.2. Preparation of guar gum–cerium (IV) tungstate (GG/CTNC)

Guar gum based nanocomposite was synthesized using ambientsol gel method. In first step, 0.1 M ceric ammonium nitrate solutionand 0.1 M sodium tungstate solution were gradually mixed withcontinuous stirring at pH 2. After complete addition, the mixturewas stirred for 5 h to obtain cerium (IV) tungstate precipitates. Theprecipitates were washed with distilled water and dried at 70 ◦C.In next step, guar gum was prepared by dissolving 0.25 g of guarpowder in the distillated water and ethanol in molar ratio of 2:1with continuous stirring at room temperature. The resultant mix-ture was allowed to stand for 24 h with occasional shaking in themother liquor for digestion. The precipitates were separated byfiltration and washed with demineralized water several times toremove excess of the reagents. The obtained precipitates were keptin 0.1 M HNO3 solution for 24 h to convert into H+ form. The pre-cipitates were filtered and washed with demineralized water toremove any excess of acid and finally dried in oven at 80 ◦C.

2.3. Batch equilibrium experiments

Adsorption experiments were performed using standard batchmethod. In this method, stipulated amount of adsorbent was addedto 100 mL of MB solution of placed in a set of 250 mL glass stop-per Erlenmeyer flasks. In each case, the mixture was agitated ina thermo shaker at a speed of 100 rpm for a given time. The sus-pensions were centrifuged at 2500 rpm for 5 min and filtered. Theequilibrium concentration MB in supernatant liquor was analyzedby standard colorimetric method using UV–visible spectropho-tometer (Shimadzu UV-1601) at 620 nm. The pH of the sample was

adjusted using 0.1 N HCl or 0.1 N NaOH solution. The percentagemetal ion removal and amount of metal ion adsorbed per unit massof adsorbent qe (mg/g) were obtained using following equations(Gupta et al., 2010):

R = C0 − Ce

C0× 100 (1)

qe = (Co − Ce)V

M(2)

where C0 and Ce are the initial and equilibrium concentrations ofMB dye (mg/L), V is the volume of the solution (L), and M is the massof the adsorbent used (g).


X-ray diffraction data were recorded using a Phillips (Hol-land), model PW 1148/89 X-ray diffractometer. Fourier transformerinfrared spectra (FTIR) were obtained using Perkin Elmer spec-trometer (Spectrum 400, USA). The surface morphology ofnanocomposite was studied using scanning electron microscope(SEM Quant-250, model 9393). The microstructure was analyzedby transmission electron microscopy (TEM) using Tecnai 20 G2(Plate/CCD Camera). The dye concentration was determined usingSystronics 117 UV–visible spectrophotometer.

2.5. Ion exchange activity of GG/CTNC

2.5.1. Ion exchange capacity0.5 g (dry mass) of GG/CTNC in H+ form was placed in a glass

tube of 1 cm internal diameter at glass wool supported at the bot-tom. The column containing GG/CTNC was washed with doubledistilled water to remove excess acid. 0.1 M NaCl (250 mL) solutionwas used as eluant to elute the H+ from GG/CTNC. The flow rate ofeluant was maintained at 0.5 mL min−1. The collected effluent wastitrated against a standard alkali solution using phenolphthalein asan indicator. The hydrogen ions released were calculated using theformula as (Siddiqui, & Khan, & Inamuddin, 2007):

IEC = N × V

Wmequiv g−1 (3)

where IEC is ion exchange capacity. N and V (mL) are normality andvolume of NaOH, respectively. W (mg) is the weight of GG/CTNC.

2.5.2. Thermal stability0.5 g sample of GG/CTNC in H+ form was heated at different tem-

peratures in muffle furnace for 1 h. The sample was weighed andion exchange capacity was determined after cooling them at roomtemperature by method as described above.

2.5.3. Effect of eluant concentrationThe optimum concentration of the eluant for complete elution of

H+ ions from CA/ZPNC was studied. 250 mL of NaNO3 solution of dif-ferent concentration was passed through the columns, containing0.5 g of the exchanger in H+ form with a flow rate of 0.5 mL min−1.The collected effluents were titrated against 0.1 M NaOH to deter-mine the eluted H+ ions.

2.5.4. Elution behaviorNaNO3 solution (1 M) was passed through a column containing

0.5 g of GG/CTNC for complete elution of H+. Effluent was collectedin 10 mL fraction at a flow rate of 0.5 mL min−1. Each fraction of10.0 mL was titrated against 0.1 M NaOH solution.


Fig. 1. (a) SEM and TEM images of GG/CTNC. (b) XRD study of guar gum–cerium (IV) tungstate composite. (C) EDX spectrum of gaur gum–cerium (IV) tungstate nanocomposite(GG/CTNC). (d) FTIR spectra of guar gum and GG/CTNC.

2.5.5. pH-titrationIn typical method, 0.5 g of GG/CTNC in H+ form was placed in

each 250 mL conical flask containing equimolar solutions of alkalimetal chlorides and their hydroxide in different volume ratios. Totalvolume was kept 50 mL to make ionic strength constant. The pH ofthe solution was recorded every 24 h until equilibrium is attainedwhich needed 10 days.

2.5.6. Distribution studiesDistribution coefficients of different metal ions such as Pb2+,

Zn2+, Th2+, Cu2+, Ni2+, Cd2+, Mg2+ were determined in aqueous solu-tion using batch process. 0.5 g of GG/CTNC in H+ form and 20 mLof different metal nitrate solutions were continuously shaken for24 h at 25 ◦C. Metal ion concentration was determined by titratingagainst standard EDTA solution. Kd values (mL/g) were determinedusing following formula:

Kd = I − F

F× V

MmL/g (4)

where I and F indicate initial and final concentration of metal ionin solution. V and M denotes final volume of the solution (mL) andamount of ion exchanger (g), respectively.


3.1. Characterization

Fig. 1a (SEM) depicts scanning electron microscopy (SEM)images of guar gum–cerium tangstate nanocomposite (GG/CTNC).GG/CTNC exhibits rough surface with different sized particles toform microsphere. TEM images signify homogeneous distribu-tion of guar gum (GG) and cerium (IV) tungstate particles (CT)in nanocomposite (Fig. 1a (TEM)). The darker portion signifies GGwrapped CT while gray part shows free GG in polymeric backbone.The high level formation of GG/CTNC can be seen in TEM image.The size of GG/CTNC was observed to be 50 nm.

Fig. 1b represents X-ray diffraction pattern of GG/CTNC. Thebroader diffraction peaks between 10◦ and 23◦ clearly were clearlyseen in GG/CTNC (Gupta et al., 2012). The low intensity broaderpeaks indicated the amorphous nature of GG/CTNC. EDX studiesconfirms that Ce, W, O, C elements are present in weight percentageof 21, 25, 40 and 9, respectively (Fig. 1c).

FTIR spectra of gaur gum and GG/CTNC were shown in Fig. 1d.The presence of a strong absorption band at 3402 cm−1 indi-cated OH bond stretching vibration. The absorption band due to


Table 1Effect of temperature on ion exchange capacity of guar gum–Ce (IV) tungstate composite exchanger.

Heating temperature (◦C) Wt. of ppts before heating (g) Wt. of ppts after heating (g) IEC for Na+ ion (mequiv g−1) Retention of ion exchange capacity

75 0.53 0.48 1.30 92.85100 0.53 0.47 1.28 91.42200 0.53 0.41 0.82 58.57300 0.53 0.40 0.64 45.71400 0.53 0.35 0.42 30.00

ring stretching of mannose may be appeared at 1655 cm−1. Theabsorption bands recorded at 1382 and 1358 cm−1 may due to sym-metrical deformations of CH2 and COH groups. The weak band at673.71 cm−1 corresponds to ring stretching and ring deformation of�-d-(1-4) and �-d-(1-6) linkages (Chauhan, Chauhan, & Ahn, 2009).In FTIR spectrum of GG/CTNC, the broad band at 3600 cm−1 corre-sponds to loosely free –OH group. The strong and broad band at3360 cm−1 may be due to free OH group. The shift in the absorp-tion frequency from 1655.96 cm−1 to 1616.31 cm−1 confirmed theinteraction of guar gum with Ce (IV) tungstate (Brigante & Schulz,2012).

3.2. Ion exchange behavior of GG/CTNC

The maximum ion-exchange capacity of the ‘GG/CTNC wasfound to be 1.3 mequiv g−1 for Na+ions. The improved ion exchangecapacity of GG/CTNC exchanger was due to the binding of poly-meric material with inorganic moiety. The nano hybrid exchangerexhibited good reproducible characteristic. Under identical condi-tions (pH 2, dosage = 0.5 g and reaction time = 24 h), GG/CTNC did

not show any appreciable change in the percentage of yield and ionexchange capacity.

Table 1 shows the effect of temperature on the ion exchangecapacity of GG/CTNC exchanger. It was revealed that ion exchangecapacity decreased with increase in temperature. GG/CTNC wasquite stable and retained about 30% ion exchange capacity evenupto 400 ◦C. The effect of eluant concentration on ion exchangecapacity of GG/CTNC was investigated (Fig. 2a). The rate of elu-tion was governed by the concentration of the eluant used onto thecomposite ion exchange materials (Inamuddin et al., 2007; Siddiquiet al., 2007). The optimum concentration of NaNO3 as eluant wasfound to be 1 M for the maximum release of H+ ions from GG/CTNC.

Fig. 2b depicts the pH titration behavior of GG/CTNC withNaOH–NaCl system. The pH titration result confirmed the mono-functional nature of nanocomposite. GG/CTNC behaved as strongcation exchanger as indicated by low pH of solution when no OH−

ions were added.The distribution studies showed that GG/CTNC exchanger was

found to be highly selective for Pb2+ as compared to other metalions. Thus the composite ion exchanger can be utilized for thedetermination and separation of lead ions from waste effluents.

Fig. 2. (a) Effect of eluent concentration on ion exchange capacity of GG/CTNC exchanger. (b) pH titration curves for GG/CTNC exchanger. (c) Effect of adsorbent dosage on MBremoval: (MB concentration = 0.32 mg/L, contact time= 120 min, pH 9, temperature = 30 ± 1 ◦C). (d) Effect of initial dye on MB removal [adsorbent dose = 0.4 g/50 ml, contacttime = 120 min, pH 9, temperature = 30 ± 1 ◦C).


The order of selectivity for different metal ions were observedas Pb (Kd = 223) Zn (Kd = 189) > Th (Kd = 90) > Cu (Kd = 65.7) > Ni(Kd = 61.0) > Cd (Kd = 59.17) > Mg (Kd = 41.5).

3.3. Effect of reaction parameter on adsorption ability ofmethylene blue onto GG/CTNC

The effect of adsorbent dosage on MB removal was studied atpH 9 and ambient temperature (30±1 ◦C). It is evident from Fig. 2cthat the removal of MB increased sharply with increase in adsor-bent dose from 0.2 g/50 mL to 0.4 g/50 mL. It was due to the reasonthat the increased adsorbent dose resulted in an increase in massgradient between the solution and adsorbent. Beyond 0.4 g/50 mLof adsorbent loading, there was no significant change in percent-age removal of MB. Therefore, due to conglomeration of adsorbentparticles, increase in effective surface area of adsorbent was negligi-ble (Gupta et al., 2007). So, 0.4 g/50 mL was considered as optimaladsorbent dosage for GG/CTNC loading and was used for furtherstudy.

Adsorption efficiency was increased with increase in MB con-centration from 0.24 mg/L to 0.32 mg/50 mL (Fig. 2d). At lower MBconcentration, the unoccupied active sites on the adsorbent surfacewere higher for adsorption. However, beyond 0.32 mg/L of MB con-centration, the number of active sites for adsorption of was lowereddue to occupation of activated site of adsorbents by dye molecule.Therefore, further increase in MB concentration did not indicate anysignificant adsorption (Constantin et al., 2013; Gupta et al., 2007).

The effect of contact time on MB removal was shown in Fig. 3a.It has been clear from Fig. 3a that about 96% dye was removedin 120 min of contact time. No significant changes in removalefficiency were observed after 120 min. The change in rate ofadsorption might be due to fact that initially all the adsorbentsites were vacant and solute concentration gradient is very high.Later, the decreased vacant sites of adsorbent resulted in lower-ing of adsorption due to monolayer formation of MB adsorbentsurface (Constantin et al., 2013; Gupta et al., 2007). So, the adsorp-tion equilibrium was attained after 120 min of contact time for MBadsorption.

Percentage removal of MB using GG/CTNC was investigatedat different solution pH. The obtained results were presented inFig. 3b. It has been revealed that the MB removal was increasedwith pH from 2 to 9. It was due to reason that on increasing pH,the surface charge of adsorbent became more and more nega-tively. It resulted in higher force of attraction between cationicMB and negatively charged adsorbent surface ultimately leadingto higher MB adsorption (Bhattacharyya & Sharma, 2005; Dogan,Alkan, Turkyilmaz, & Ozdemir, 2004).

3.4. Isotherm data analysis

The adsorption isotherms revealed the specific relationshipbetween adsorbate concentration in the bulk and adsorbed amountat interface. In this study, equilibrium data was modeled by usingLangmuir, Freundlich and Tempkin isotherm equations (Guptaet al., 2007; Dogan et al., 2004). Langmuir isotherm was given byfollowing equation (Langmuir, 1918):

Ce

qe= 1

bq0+ 1

bCe (5)

where qe is amount of adsorbate adsorbed per unit weight of adsor-bent (mg/g), q0 is the monolayer adsorption capacity (mg/g), Ce

is the initial concentration(mg/L) and b is the Langmuir constant(L/mg). In order to determine the feasibility of adsorption process,

Table 2Isotherm model for MB adsorption onto GG/CTNC.

Models Isotherm constants

Langmuir qm (mg/g) b (L/mg) RL R2

120.68 3.25 0.918 0.991.14 0.593 Kf (mg/g) – R2

A (L/g) – – 0.93Temkin B R2

0.058 – 530 0.98

dimensionless constant separation term (RL) may be expressed as(Gupta et al., 2010):

RL = 11 + bCe

(6)

The obtained RL values (0 < RL < 1) favored the adsorption of MBonto adsorbents. From Table 2 and Fig. 3c, the value of correlationcoefficients was very high, indicating a good fit of monolayer Lang-muir model to the adsorption of MB by GG/CTNC (Bhattacharyya &Sharma, 2005; Dogan et al., 2004).

Freundlich isotherm model was given by following equation(Freundlich, 1906):

log qe = log Kf + 1n

log Ce (7)

where adsorbate Kf and qe are Freundlich adsorption constants,which can be determined by the linear plot of log qe and log Ce.The value of correlation coefficient (R2) was observed to be 0.93.MB adsorption onto GG/CTNC did not follow Freundlich isothermmodel closely. The value of n more than unity (1.14) was an indi-cation of significant adsorption onto the adsorbent (Bhattacharyya& Sharma, 2005; Dogan et al., 2004).

Temkin isotherm assumes that heat of adsorption of all themolecules in the layer decreases linearly with coverage due toadsorbent-adsorbate interactions (Temkin & Pyzhev, 1940). Thefollowing equation represents Tempkin isotherm model.

log qe = ̌ ln ̨ + ̌ ln Ce (8)

where ̌ = (RT)/b, T is absolute temperature in Kelvin and R is uni-versal gas constant, 8.314 J (mol K)−1. The adsorption data wasanalyzed according to the linear form of Temkin isotherm. Thelinear regression R2 (0.987) was higher than Frendlich isothermmodel (Table 2). Therefore, MB adsorption onto GG/CTNC followedTempkin isotherm closely than Frendlich isotherm (Gupta & Ali,2008).

3.5. Adsorption kinetics

The kinetic study was important to describe the time depend-ence of system under various conditions. The pseudo first orderrate constant was given by following equation (Ho & McKay, 1999;Zacar & Engil, 2004):

log (qe − qt) = log qe − k1

2.303t (9)

where qt and qe are the adsorption capacities at contact time andat equilibrium time, respectively. k1 is rate constant for adsorptionprocess.

The pseudo second order rate equation was described by follow-ing equation (Gupta et al., 2010; Ho & McKay, 1999; Zacar & Engil,2004):

t

qe= 1

k2q2e

+ t

qe(10)

where k2 is rate constant of pseudo second order equation(g/mg min). The value qe and qt are the adsorption capacity at equi-librium and at time t, (mg/g) respectively.


Fig. 3. (a) Effect of contact time on MB removal. (MB concentration = 0.32 mg/L, adsorbent dose = 0.4 g/50 ml, pH 9, temperature = 30 ± 1 ◦C). (b) Effect of pH on MB removal.(MB concentration = 0.32 mg/L, adsorbent dose = 0.4 g/50 ml, contact time = 120 min., temperature = 30 ± 1 ◦C). (c) Langmuir adsorption isotherm for MB removal. (d) Pseudofirst order kinetics for MB removal.

The pseudo second order kinetics was fitted well with theexperimental data as compared to pseudo first order kinetics(Figs. 3a and 4a and Table 3). The correlation coefficients werein good agreement with pseudo second order kinetic models(R2 > 0.99) (Table 3). The high value of R2 and applicability ofpseudo second kinetics indicated that the adsorption process wasenhanced by chemisorptions (Fig. 4 and Table 3). So, chemisorp-tion was the rate-controlling mechanism for the adsorption process(Gupta et al., 2010; Ho & McKay, 1999; Zacar & Engil, 2004).

The possibility of intraparticle diffusion was determined byusing following equation (Gupta et al., 2007):

qt = kidt1/2 + C (11)

where C is intercept and Kid is intraparticle diffusion rate con-stant (mg/L min1/2). Plot of qt versus t1/2 should be linear if

Table 3Kinetic model for MB adsorption onto GG/CTNC.

Pseudo first order modelk1 (min−1) qe (exp.) qe (mg/g) R2

0.0230 120.68 100.17 0.94

Pseudo second order modelk2 (g/mg min) qe (mg/g) R2

0.00125 118.305 0.99Intraparticle diffusion modelKid (mg/g min1/2) C (mg/g) R2

0.682 3.134 0.893

intraparticle diffusion is involved in the adsorption process. Theresults of intraparticle diffusion were shown in Fig. 4b and Table 4.The linear portion of the plot did not pass through origin. This devi-ation from the origin was due to the variation of mass transferin the initial and final stages of adsorption. The adsorption pro-cess occurred in two or more steps. At final equilibrium stage, theintraparticle diffusion slowed down due to saturation of adsorbentand MB was slowly transported into the pores and retained in themicropores (Bhattacharyya & Sharma, 2005; Dogan et al., 2004).The adsorption process has not obeyed the intraparticle diffusionmodel.

3.6. Effect of temperature and adsorption thermodynamics

The effect of temperature on the adsorption was investigatedunder optimized conditions (Fig. 4c). It was observed that adsorp-tion of MB decreased with increase in temperature from 303–343 K.The decrease in adsorption capacity with temperature was due to

Table 4Thermodynamic parameters for MB adsorption at temperature range of 303–343 K.

Temperature (K) �G (KJ/mol) �H (KJ/mol) �S (KJ/K mol)

303 −0.95 3.66 0.044313 −1.35 3.00 0.04323 −2.85 2.75 0.035333 −4.25 2.35 0.030343 −5.27 2.00 0.027


Fig. 4. (a) Pseudo second order kinetics for MB removal. (b) Intraparticle diffusionplot for MB removal. (c) Effect of temperature on MB adsorption. (MB concentra-tion = 0.32 mg/L, adsorbent dose = 0.4 g/50 ml, contact time = 120 min, pH 9).

the weakening of the adsorptive forces between the active sitesof adsorbent surface and adsorbate (Arami, Limaee, & Mahmoodi,2008). The main criterion which leads to a chemisorption orphysisorption was the determination of the enthalpy �H. Ther-modynamic parameters such as Gibbs free energy (�G), enthalpy(�H) and entropy (�S) were given by using the following equations(Arami et al., 2008; Gupta & Ali, 2008).

�G = −RT ln (Kc) (12)

�G = �H − T�S (13)

log Kc = �S

R− �H

2.303RT (14)

where Kc is the equilibrium constant of the adsorption and may bedefined as:

Kc = Cadsorbent

Csolution(15)

where Cadsorbent and Csolution are the concentration of MBonto the adsorbents and residual MB concentration atadsorption–desorption equilibrium. The value of enthalpy (�H)and entropy (�S) were calculated from the slope and interceptsof the plot of log Kc versus 1/T (Fig. 4c). Table 4 shows the ther-modynamic parameters for the adsorption MB onto GG/CTNC. The

negative value of Gibbs free energy indicated the spontaneousnature of adsorption process and the degree of spontaneity ofthe reaction increased with increase in temperature (Table 4).Adsorption process seemed to be endothermic in nature. Theseresults supported that adsorption mechanism was primarilychemisorptions. The positive value of �S suggested the increasedrandomness at the solid-solution interface due to the redistribu-tion of energy between adsorbent and adsorbate during adsorptionprocess. In the beginning of adsorption process, adsorbate ionswere heavily solvated and the system became more ordered.However, the order was lost when the ions were adsorbed on thesurface due to the release of solvated water molecules.

4. Conclusion

Guar gum–Ce (IV) tungstate was prepared by sol gel method. Ionexchange capacity of hybrid ion exchanger for Na+ ion was notedto be 1.3 mequiv g−1. pH titrations indicated the mono functionalnature of GG/CTNC. Spectral studies confirmed the formation ofGG/CTNC. Guar gum based ion exchanger was highly selective forlead metals. Optimization of different parameters such as dosage,initial dye concentration and contact time for adsorption of methy-lene blue dye was studied. The optimum parameters for adsorptionof MB onto GG/CTNC was found to be MB concentration 0.32 mg/L,adsorbent dose 0.4 g/50 mL, contact time 120 min, temperature30 ± 1 ◦C. The adsorption of MB followed pseudo first second orderkinetics. The adsorption studied showed the endothermic natureof adsorption process. This study revealed the applicability ofGG/CTNC for environmental remediation involving the dye removalfrom aqueous phase.

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jo ur nal homep age: www.elsev ier .com/ locate /carbpol

Synthesis, characterization and antibacterial activity of celluloseacetate–tin (IV) phosphate nanocomposite

Bhim Singh Rathorea, Gaurav Sharmaa, Deepak Pathaniaa, Vinod Kumar Guptab,∗

a Department of Chemistry, Shoolini University, Solan 173212, Himachal Pradesh, Indiab Department of Chemistry, Indian Institute of Technology Roorkee, Roorkee 247667, India


Article history:Received 9 November 2013Received in revised form30 November 2013Accepted 3 December 2013Available online 12 December 2013

Keywords:Cellulose acetateNanocompositeCharacterizationIon exchange propertyAntibacterial

a b s t r a c t

Cellulose acetate–tin (IV) phosphate nanocomposite (CA/TPNC) was prepared using simple method at0–1 pH. The nanocomposite ion exchanger was characterized using some techniques such as Fouriertransform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), scanning electronmicroscopy (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), and thermo-gravimetric analysis (TGA/DTA/DSC). The nanocomposite material was explored for different propertiessuch as ion exchange capacity, pH titration, elution behavior, thermal stability, and distribution coeffi-cient. The ion exchange capacity of CA/TPNC was found higher compared to their inorganic counterpart.The distribution coefficient studies of nanocomposite ion exchanger were investigated for different metalions. On the basis of distribution coefficient studies CA/TPNC material was found more selective for Cd2+

and Mg2+. CA/TPNC ion exchange was explored for antibacterial activities against E. coli bacteria.© 2013 Elsevier Ltd. All rights reserved.

1. Introduction

Extensive industrialization has led to the degradation of aquaticenvironment due to the discharge of non-degradable and haz-ardous material into the aquatic system. The toxic heavy metalsare common constituents present in polluted water. If the concen-trations of these metals are present above certain limit, it causesserious health hazard to living beings (Nabi, Naushad, & Inamuddin,2007). So it is important to treat the wastewater before dischargedto natural water bodies. The toxic metal ions were difficult toremove due to their unmanageable nature and resistant to naturaldegradation (Gao et al., 2007; Gupta, Agarwal, & Saleh, 2011; Gupta,Ali, & Saini, 2007; Gupta, Ali, Saleh, Nayak, & Agarwal, 2012; Gupta,Chandra, & Lang, 2006; Gupta, Chandra, & Mangla, 2002; Gupta,Gupta, & Rastogi, 2011; Gupta, Jain, & Kumar, 2006; Gupta, Jain,Radhapyari, Jadon, & Agarwal, 2011; Gupta, Jain, & Varshney, 2007;Gupta, Mittal, Malviya, & Mittal, 2009; Gupta, Pathania, Singh,Rathore, & Chauhan, 2013; Gupta, Rastogi, & Nayak, 2010; Jain,Gupta, Bhatnagar, & Suhas, 2003; Goyal, Gupta, & Chatterjee, 2009;Vilhera, Goncalves, & Mota, 2004; Zeng, Pan, & Gao, 2008; Zhao,Zhao, Le, Zeng, & Gao, 2007). Due to multifold increase in waterpollution, there have been growing interests in the fabrication ofnew composite ion exchanger with diverse applications.

∗ Corresponding author. Tel.: +91 1332285801; fax: +91 1332273560.E-mail addresses: [email protected], [email protected] (V.K. Gupta).

Many organic and inorganic ion exchangers have been reportedin literature with wide utility but suffer from certain limita-tions. The organic exchangers were unstable at high temperatureand ionization radiation (Gupta, Pathania, Agarwal, & Singh,2012; Nabi & Naushad, 2008). The fine powder form of inor-ganic ion exchangers made them unsuitable for column operation(Khan, Alam, & Inamuddin, 2005; Mojumdar, Varshaney, &Agarwal, 2006; Nabi, Naushad, & Bushra, 2009a; Nabi, Naushad,& Bushra, 2009b). Composite ion exchangers have been preparedby incorporating an organic polymer into the matrix of inor-ganic precipitates using sol–gel mixing method (Clearfield, 1982;Khan et al., 2005; Khan, Niwas, & Alam, 2002; Siddiqui, Khan,& Inamudin, 2007). The organic part enhanced the mechanicalproperties and surface area by providing more exchanging siteson inorganic counterpart of the composite ion exchange materi-als (Khan et al., 2005; Mojumdar et al., 2006; Nabi et al., 2009a,2009b).

Composite ion exchangers have received attention becauseit possessed interesting mechanical, chemical, electrochemical,optical and magnetic properties (Hassan, Marei, Badr, & Arida,2001; Khan & Paquiza, 2011). Therefore, composite ion exchang-ers have been used as adsorbent, catalyst, ion selective electrode,antimicrobial activity, chromatography and environmental scienceengineering (Arrad & Sasson, 1989; Gupta, Ali, et al., 2007; Gupta,Jain, et al., 2007; Gupta, Pathania, et al., 2013; Nabi et al., 2009a,2009b; Nabi, Shahadat, Bushra, Shalla, & Ahmed, 2010; Sanghavi,Mobin, Mathur, Lahiri, & Srivastava, 2013; Sanghavi, Sitaula, et al.,





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222 B.S. Rathore et al. / Carbohydrate Polymers 103 (2014) 221– 227

2013; Sanghavi & Srivastava, 2013; Mittal, Gupta, Malviya, & Mittal,2008; Mittal, Mittal, Malviya, & Gupta, 2009; Mittal, Mittal, Malviya,& Gupta, 2010; Mittal, Mittal, Malviya, Kaur, & Gupta, 2010). Thecomposite materials at nano level have many properties supe-rior to the bulk materials due to their selectivity, specificity andwide range of applicability (Gupta, Pathania, et al., 2013). Thus,the efforts have been made to magnify the chemical, mechanicaland thermal stability and selectivity of composite ion exchangers(Bushra, Shahadat, Raeisssi, & Nabi, 2012; Islam & Patel, 2008; Nabi& Naushad, 2008).

Cellulose based nanocomposites have been reported world-wide due to their cost-effectiveness, high-volume application,easy process ability, renewable nature and possibility of recycling.Nanocomposites based on cellulosic material have been reportedin the literature (Gadhari, Sanghavi, & Srivastava, 2011; Gupta,Pathania, et al., 2013; Park & Kadla, 2012; Sanghavi & Srivastava,2010; Yang et al., 2012). The biopolymer based materials have beenused effectively and economically for wastewater treatment.

The antimicrobial activities of nanocomposite against microor-ganism were investigated by different research groups usingvarious methods (Nabi, Shahadat, Bushra, Oves, & Ahmed, 2011;Rekha, Nirmala, Nair, & Anukaliani, 2010). The metal nanoparticleshave been incorporated into biodegradable polymers such as chi-tosan, gelatin and both polymers via chemical reduction methodto produce composites materials with some extraordinary prop-erties. The effect of polymers and the size of nanoparticles on theantibacterial activity of silver bionanocomposite have been investi-gated (Ahmad et al., 2012). The nano materials, based on metal ions,exhibit broad spectrum biocidial activity toward different fungi,bacteria and viruses (Greenberg & Graves, 2005).

The literature survey revealed that so far no work has beendocumented on the synthesis and antibacterial activity of cel-lulose acetate–tin (IV) phosphate nanocomposite (CA/TPNC) ionexchanger. Thus, the present study deals with the preparation ofcellulose acetate–tin (IV) phosphate nanocomposite ion exchanger.The CA/TPNC has been explored for the antibacterial activity againstE. coli bacteria. CA/TPNC was characterized by scanning elec-tron transmission (SEM), transmission electron microscopy (TEM),energy dispersive X-ray spectroscopy (EDX), thermogravimetricanalysis, X-ray diffraction (XRD) and Fourier transform infraredspectroscopy (FTIR).

2. Experimental

2.1. Reagents

The reagents used were tin (IV) chloride and sodium dihydro-genphosphate (LobaChemia Pvt. Ltd., Mumbai, India), formic acid(E. Merck Ltd., India), and cellulose acetate (CDH, Pvt. Ltd., NewDelhi, India). All the reagents were used as received without furtherpurification. Double distilled water was used for the preparation ofsolutions.


A digital pH meter (Elico LI-10, India), FTIR spectropho-tometer (Perkin Spectrum-400), X-ray diffractrometer (X’pert ProAnalytical, Switzerland), scanning electron microscope (JEOL, JSM-6610LL, Japan), transmission electron microscopy (Hitachi, H7500,Germany), muffle furnace (MSW-275, India), magnetic stirrer anddigital oven were used.

2.3. Synthesis of cellulose acetate–tin (IV) phosphate (CA/TPNC)

Cellulose acetate–tin (IV) phosphate nanocomposite ionexchanger was synthesized using sol–gel method at 0–1 pH as

per method discussed in the literature (Gupta, Agarwal, Pathania,Kothiyal, & Sharma, 2013). In this, 0.1 M sodium dihydrogen phos-phate and 0.1 M tin (IV) chloride were mixed in 1:1 ratio withconstant stirring at room temperature. The pH of resulting mix-ture was adjusted to 0–1 by adding 0.1 N HNO3. After completeaddition, the mixture was stirred for 2 h to obtain the precipitatesof tin (IV) phosphate (TP). The gel of cellulose acetate (CA) in formicacid was prepared and added to the precipitates of tin (IV) phos-phate with continuous stirring. The resultant mixture was stirredfor 4 h on the magnetic stirrer. This mixture was kept for digestionfor 24 h with occasional shaking. The precipitates were filtered andwashed with double distilled water several times to remove theimpurities if present. The precipitates of cellulose acetate–tin (IV)phosphate obtained were dried at 50 ◦C in a hot air oven. The driedprecipitates were converted into H+ by putting in 0.1 M HNO3 solu-tion for 24 h with occasional shaking. The precipitates of CA/TPNCwere filtered and washed with distilled water to remove the excessof the acid. In a similar way different samples of nanocompositeion exchanger have been synthesized and ion exchange capaci-ties were determined. The ion exchange capacity of Sample-4 wasfound maximum and selected for further studies.

2.4. Ion exchange capacity (IEC)

The ion exchange capacity of CA/TPNC was determined by thestandard column process as explained earlier in the literature(Pathania, Singh, & Siddiqi, 2013; Siddiqi & Pathania, 2003a; Siddiqi& Pathania, 2003b). In this process, 1 g of CA/TPNC material in H+

ions form was kept in a glass column fitted with glass wool sup-port at the bottom.1 M sodium chloride solution was used to elutethe H+ ions completely from the CA/TPNC exchanger, maintaining aflow of 1.0 mL min−1. The effluent was collected and titrated againststandard alkali solution to determine the total H+ ions released.The ion exchange capacity of the CA/TPNC was calculated using theformula as:

IEC (mg/g) = N × V

W(1)

where IEC is the ion exchange capacity. N and V (mL) are normalityand volume of the alkali solution, respectively. W (g) is the amountof CA/TPNC.

2.5. pH titration

Topp and Pepper method was used to perform the pH-titrationstudies (Topp & Pepper, 1949). In this method, 0.4 g of CA/TPNC inH+ was taken each in 250 mL conical flasks. The equimolar solutionalkali metal hydroxides and their chlorides in different volume ratiowere added into the flasks by adjusting the final volume as 50 mL.The pH of solutions was recorded at regular interval of 24 h untilthe equilibrium was established.

2.6. Effect of eluent concentration

A fixed volume (250 mL) of sodium nitrate solution of differentconcentrations were used for complete elution of H+ ions from theCA/TPNC. The eluent was passed through column containing 1 g ofCA/TPNC with a flow rate of 1 mL min−1. The collected effluent wastitrated against 0.1 M NaOH solution.

2.7. Elution behavior

1.0 M NaNO3 eluent concentration was observed for the com-plete removal of H+ ions from the CA/TPNC ion exchanger. A columncontaining 1 g of CA/TPNC in H+ form was eluted with 1.0 M NaNO3solution. The effluent was collected in fractions of 10 mL at a flow

B.S. Rathore et al. / Carbohydrate Polymers 103 (2014) 221– 227 223

Table 1Condition of syntheses and ion exchange capacity of different samples of CA/TPNC.

Sample no. A (mol L−1) B (mol L−1) pH Mixing ratio (v/v) C (%) Appearance IEC (mequiv./g)

S-1 0.1 0.1 0-1 1:1 0 White 0.55S-2 0.1 0.1 0-1 1:1 1 White 0.68S-3 0.1 0.1 0-1 1:1 2 White 0.68S-4 0.1 0.1 0-1 1:1 4 White 1.48S-5 0.1 0.1 0-1 1:1 6 White 1.10S-6 0.1 0.1 0-1 1:1 8 White 0.75S-7 0.1 0.1 0-1 1:1 10 White 0.40

A: tin (IV) chloride; B: sodium dihydrogen phosphate; C: cellulose acetate (in 25 ml formic acid).

rate of 1 mL min−1. Each collected fraction was titrated againststandard NaOH solution.

2.8. Thermal stability

The effect of drying temperature on the ion exchange capacitywas investigated by heating CA/TPNC at different temperatures ina muffle furnace for 1 h. After cooling the sample in desiccators theion exchange capacity was determined by standard column method(Innamuddine, Khan, Siddiqui, & Khan, 2007).

2.9. Distribution coefficient studies (Kd)

The distribution coefficients of different metal ions ontoCA/TPNC in double distilled water were determined by batchmethod. In this, 300 mg of CA/TPNC in H+ charged was equili-brated with 20 mL different metal nitrates in Erlenmeyer flask. Themixture was shaken for 24 h at room temperature to attain the equi-librium. The concentration of metal ions in the solution before andafter equilibrium were determined by titrating against standardsolution of EDTA (Reilley, Schmid, & Sadek, 1959). The distributioncoefficient (Kd) was calculated by using equation

Kd (mL g−1) = I − F

F× V

M(2)

where I (g/L) and F (g/L) are the initial and final concentration of themetal ions in solution, respectively. V is the volume of the solution(mL) and M is the amount of CA/TPNC (g).

2.10. Antibacterial activities

The colony forming unit (CFU) method was used to investi-gate the antibacterial activity of CA/TPNC ion exchanger againstE. coli bacteria culture. In this method, 1 mL of 0.5 optical densityE. coli bacteria culture was taken and inoculated into the control

and nanocomposite samples. The samples were diluted up to 10−3

by serial dilution method and plated on nutrient agar plates. Theplates were incubated at 37 ◦C for 2 h and 24 h. The colonies werecounted with the help of colony counter and the results obtainedwere compared with CFU of E. coli culture.

2.11. Fourier transform infrared spectroscopy (FTIR)

FTIR spectrum of CA/TPNC (S-4) was recorded by using KBr diskmethod. In this technique, 10 mg of material was thoroughly mixedwith 100 mg of KBr. An appropriate pressure was exerted to forma transparent disk. The FTIR spectrum of CA/TPNC was recordedbetween 400 and 4000 cm−1.

2.12. X-ray studies

The X-ray diffraction pattern of the nanocomposite ionexchanger was recorded by X-ray diffractometer using Cu K� radi-ation. The spectrum was recorded between 10◦ and 80◦ at 2�.

2.13. Scanning electron microscopy (SEM) and energy-dispersiveX-ray (EDX) studies

Scanning electron microphotographs of CA/TPNC (Sample-4)were recorded at different magnifications using scanning electronmicroscope. The elemental composition of the nanocomposite ionexchanger was determined by energy dispersive X-ray coupledwith scanning electron microscopy.

2.14. Transmission electron microscopy (TEM)

The particles size and morphology of CA/TPNC ion exchangerwas analyzed using high resolution transmission electronmicroscopy Hitachi, H7500, Germany.

3SnCl4 + 4NaH 2PO 4 Sn 3(PO4)4 + 4NaCl + 8HCl

TP

30oC

pH = 0-1

Sn3(PO4)4 +

OR

CH2OR

O

OR

O

CH2OR

O

OR CH2OR

ORCH2OR

OO

O

OO

OR

CH2OR

n Sn P

O

O

O

O

O

O

OR

----

---

----

---

----

----

----

CA

CA/TPNC

OR

OR

TP

OR

OR

R = CH3CO

Fig. 1. Proposed reaction for the synthesis of cellulose acetate–tin (IV) phosphate nanocomposite.


Fig. 2. (a) Effect of eluent concentration on ion exchange capacity of CA/TPNC. (b)Elution behavior of CA/TPNC. (c) pH titration curve of CA/TPNC.

2.15. Thermal analysis

The thermal analysis of CA/TPNC was determined by heatingthe sample up to 700 ◦C at a constant rate of 10 ◦C/min in nitrogenatmosphere.


The various samples of cellulose acetate–tin (IV) phosphatenanocomposite (CA/TPNC) ion exchanger were synthesized by mix-ing inorganic tin (IV) phosphate and organic cellulose acetate.Table 1 shows the effect of mixing ratio of reagent, reaction tem-perature and pH on the synthesis of CA/TPNC ion exchanger.The sample, S-4 shows enhanced Na+ ion exchange capacity(1.48 mequiv./g) and better yield, compared to inorganic counter-part (0.55 mequiv./g) and other samples. Due to better yield, highion exchange capacity, thermal stabilities and good reproducibil-ity, sample-4 (S-4) was selected for further detailed studies. Theincrease in Na+ ion exchange capacity for CA/TPNC may be due tothe binding of organic part (CA) with inorganic tin (IV) phosphate(TP) constituents (Fig. 1).

The effect of temperature on the ion exchange capacity of theCA/TPNC (sample-4) was shown in Table 2. It has been revealed thatCA/TPNC ion exchanger was thermally stable and retained the ionexchange capacity up to 31.75 mequiv./g at 400 ◦C. The retentionion exchange capacity was higher compared with other compositeion exchange found in literature (Gupta, Agarwal, et al., 2013). Thegradual decrease in ion exchange capacity with temperature wasdue to degradation of organic counterpart pectin.

The effect of eluent concentration on the release of H+ ions fromthe CA/TPNC ion exchanger was shown in Fig. 2. An optimum con-centration of sodium nitrate (eluent) was found to be 1.0 M for thecomplete removal of H+ ions from the CA/TPNC column. It has beenrecorded that the rate of elution of H+ ions from the CA/TPNC wasgoverned by the concentration of eluent used.

Tem p Cel700.0600.0500.0400.0300.0200.0100 .0

DT

A u

V

40 .0

20.0

0.0

-20.0

-40.0

-60.0

-80.0

-100 .0

-120 .0

TG

mg

30 .00

28.00

26.00

24.00

22.00

20.00

18.00

16.00

14.00

12.00

DT

G m

g/m

in

2 .500

2.000

1.500

1.000

0.500

0.000

69.3Cel0.342 m g/m in

104.9Cel0.312 m g/m in 258.7Cel0.240 m g/m in 322.1Cel

0.250 m g/m in691.9Cel0.003 m g/m

503.5Cel0.051 m g/m in

46.9Cel23.10 m g 135.2Cel

20.78 m g 241.6Cel19.90 m g

341.9Cel18.02mg

461.9Cel17.31 m g 592.7Cel

16.86 m g651.7Cel16.82 m g

32.0Cel-3.7uV

73.2Cel-11 .7uV

168.2Cel3.1u V

327.1Cel16.1uV

421.1Cel12.1u V 481.8Cel

10.8uV588.7Cel4.5u V

680.3C el1.5uV

0.030 m g/m in

0.076mg/m in

0.011 m g/m in0.200 m g/m in

0.049 m g/m in

Fig. 3. Thermal analysis of CA/TPNC.


Fig. 4. (a) FTIR spectrum, (b) X-ray diffraction pattern and (c) EDX of CA/TPNC.

Fig. 2 illustrates the elution behavior of CA/TPNC ion exchangerat optimized concentration of eluent. It was established that 120 mLsolution of 1.0 M sodium nitrate was sufficient for the completeremoval of H+ ions from CA/TPNC.

The pH titration curve of CA/TPNC ion exchanger under equi-librium condition was studied in NaOH–NaCl as shown in Fig. 2.The results confirmed the monofunctional strong cation exchangernature of nanocomposite. The strong cationic nature of CA/TPNC ionexchanger was evident from the low initial pH of the solution whenno OH− ions were added to the system (Gupta, Pathania, Singh,Kumar, & Rathore, 2014). Further rise in pH indicated the completeneutralization of H+ ions of the CA/TPNC exchanger.

The distribution studies (Kd) of 10 different metal ionssuch as Cd2+, Cu2+, Pb2+, Zn2+, Cr3+, Co2+, Fe3+, Ni2+, Mn2+ andMg2+ was explored on the CA/TPNC. The distribution studiesexhibited the highly selective nature of CA/TPNC for Cd2+ ascompared to other metal ions. Hence the nanocomposite ionexchanger can be utilized for detection and segregation ofcadmium ions from waste effluents. However, the Kd valuesshowed the sequence of selectivity for different metal ions asCd2+ (568.2) > Mg2+ (480.2) > Pb2+ (366.2) > Zn2+ (344.6) > Cr3+

(241.4) > Co2+ (232.4) > Fe2+ (231.9) > Ni2+ (220.0) > Mn2+

(152.6) > Cu2+ (122.4).The thermal analysis of CA/TPNC ion exchanger was shown

in Fig. 3. It was apparent from the thermogram that initialloss of about 10% up to 140 ◦C. It may be due to loss ofexternal water molecules present on the surface of the sam-ple (Duval, 1963). The nanocomposite ion exchanger was foundthermally stable as only 2% weight loss occurred between 100and 350 ◦C. It was due to the conversion of some phosphateinto pyrophosphate (Innamuddin et al., 2007). Further, a slightloss of weight about 6% was observed from 350 to 700 ◦C dueto the decomposition of organic part of the nanocompositematerial.

The FTIR spectrum of CA/TPNC ion exchanger was shown inFig. 4(a). The absorption peak at 3432 cm−1 may be due to presenceof external water molecule. The absorption band at 1744 cm−1 maybe due to carbonyl group of cellulose acetate. The presence of sharp

Fig. 5. (A) SEM images. (B) Inset TP. (C and D) TEM images of CA/TPNC.


Table 2Effect of temperature on ion-exchange capacity of CA/TPNC.

Sr. no. Heating temperature (◦C) Appearance Weight loss (%) Na+ ion exchange (mequiv./g) Retention of IEC (%)

1 50 White Nil 1.48 1002 100 White 13.6 1.39 93.913 150 Brown 17.6 1.21 81.754 200 Brown 20.8 1.10 74.325 250 Dark brown 26.3 1.01 68.246 300 Dark brown 28.3 0.84 56.757 350 Dark brown 32.2 0.59 39.868 400 Dark brown 37.9 0.47 31.75

Fig. 6. Antimicrobial activity of CA/TPNC against E. coli.

peak at 1633 cm−1 may be due to free water molecule and stronglybonded –OH group in the matrix (Pathania et al., 2013). The broadpeak observed at 1039 cm−1 may be due to PO4

3−, and H2PO4−

(Nabi & Naushad, 2008). The absorption band at 490 cm−1 may bedue to superposition of metal-oxygen stretching vibrations con-firming binding between cellulose acetate and tin (IV) phosphate(Siddiqui et al., 2007).

X-ray diffraction (XRD) pattern of CA/TPNC ion exchanger waspresented in Fig. 4(b). It showed small peaks thereby suggestingthe semi crystalline nature of nanocomposite material.

The EDX spectrum confirmed that tin and phosphate were maincomponents present in the CA/TPNC ion exchanger (Fig. 4(c)).

The surface morphology of CA/TPNC ion exchanger at differentmagnifications was determined by scanning electron microscopy(SEM) and presented in Fig. 5(A) and (B). The SEM results con-firmed the rough morphology of CA/TPNC compared to inorganiccounterpart TP.

Transmission electron microscopy (TEM) images of CA/TPNCat different magnification were shown in Fig. 5(C) and (D). TheTEM results revealed particle size in the range between 3.71 and4.01 nm.

The antibacterial activity of CA/TPNC ion exchanger was inves-tigated against E. coli bacteria culture and documented in Fig. 6.It was evident that CA/TPNC ion exchanger inhibits the growthof E. coli bacteria. This was due to the binding of nanocompositeparticles to the outer membrane of E. coli which resulted in the inhi-bition of active transport, dehydrogenase and periplasmic enzymeactivity. The maximum antibacterial activity of nanocomposite ionexchanger was observed at 200 �g/mL concentration. It has beenobserved that with the increase in the concentration of CA/TPNC,the antibacterial effect was more pronounced. This indicates thebiostatic nature of nanocomposite ion exchanger.

4. Conclusion

The CA/TPNC ion exchanger with elevated ion exchange capacityand thermal stability was synthesized by co-precipitation method.

CA/TPNC was explored for various characterization techniques. Thenanocomposite ion exchanger retained good ion capacity at highertemperature. The nanocomposite ion exchanger was investigatedto be highly selective for Cd2+ compared to other metal ions. TEMstudy confirmed that nanocomposite ion exchanger was in nanorange. CA/TPNC was studied for the antibacterial activity againstE. coli.

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Chalcogenide Letters Vol. 8, No. 6, June 2011, p. 396 - 404

SYNTHESIS, CHARACTERIZATION AND PHOTOCATALYTIC APPLICATION OF BOVINE SERUM ALBUMIN CAPPED CADMIUM

SULPHIDE NANOPARTILCES

DEEPAK PATHANIAa*

* Corresponding author:

, SARITAa, BHIM SINGH RATHOREb aDepartment of Chemistry, Shoolini University of Biotechnology and Management Sciences, Solan -173212, Himachal Pradesh, India bDepartment of Chemistry, Government P.G. Degree College, Solan -173212, Himachal Pradesh, India Cadmium sulphide nanoparticles (NPs) have been synthesized in aqueous phase at temperature range 700C using Bovine Serium Albumin (BSA) as the capping agent. Cadmium sulphide nanocrystals are synthesized by dissolving 0.1 M CdSO4, 0.1 M Na2S and BSA as stabilizing agent. Cadmium sulphide nanoparticles have been characterized with the help of X-ray diffraction (XRD), Transmission electron microscopy (TEM), Thermal analysis (TGA/DTA) and UV-Visible spectroscopy. The average particle size were found to be in the range of 3.1 – 3.8 nm from the peak broadening of X-ray diffraction. The CdS Nanoparticles have been effectively used for the removal of methylene blue from water samples in presence of visible sunlight and sodium lamp source. (Received May 23, 2011; Accepted June 23, 2011) Keywords: Cadmium sulphide, Methylene blue, Photocatalyst, SEM, XRD, BSA

1. Introduction Nano sized particles have attracted great deal of attraction in the recent years due to their

unique optical, electrical, chemical properties. Unlike the bulk materials, the emission wavelength of the nanoparticle (quantum dots) depends on their crystal dimension. Therefore many researchers have focused on the production of nanomaterials that have controllable size. Among the semiconductor nanocrystals, CdS is one of the most important II-VI group elements possessing size tunable optical transitions. Cadmium sulphide is a solid hexagonal or cubic crystal. CdS is an important n – type semiconductor with a direct band gap of 2.42 eV at 300K. Much effort has been given to the synthesis and to study the optical property of CdS related nano particles and quantum dots because they have wide applications for laser light emitting diodes, solar cells and some optoelectronic devices based on nonlinear properties [1-5]. The optoelectronic applications including solar cells, photodiodes, light emitting diodes, nonlinear optics, photoelectrochemical cells and heterogeneous photo catalysis [6-8]. The photoconductive and electroluminiscent properties of cadmium sulphide have been applied in manufacturing a variety of consumer goods. Several methods have been reported different shape controlled morphologies of CdS nanoparticles [9-12].

The appropriate use of nanoparticles for biological labeling requires the coating with biological receptor. The biomolecules have strong affinity for the nanocrystal structures. Therefore, this application of nanoparticles is achieved if the synthesis is carried out in presence of appropriate biomolecules. With surfactant assisted synthesis, the surfactants are the best suitable for the charge and steric stabilization to attain colloidal stability. When instead of surfactant, amphiphilic biomolecules are used for the synthesis of bioconjugate nanoparticles the same stability can be achieved [13].

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397

Bovine serum albumen (BSA) a low molecular weight, water soluble and active carrier protein as a capping agent to synthesize BSA-CdS biocounjugate nanoparticles have been taken in the present study. BSA is an important blood protein with molecular weight of 66500 Da, is composed of 580 amino acid residue [14]. It is versatile carrier protein with wide hydrophobic, hydrophilic, anionic and cationic properties. The synthesis of various metal and semiconductor nanoparticles has been reported using BSA as capping agent [15-17]. BSA is weakly reducing and can act as shape directing agent to promote anisotropic growth [16]. Numbers of studied have reported the heat induced denaturation of BSA [18]. It remains stable up to 600C, above this temperature the unfolding progresses and β–aggregation begins. The main advantage of this method is that the nanoparticles obtained at the end of the reaction can directly be used for specific bioactive functionalities.

In last decade photocatalytic degradation using semiconductors have been shown to be effective for destruction of pollutants. Several semiconductors such as ZnO, ZnS, TiO2, Fe2O3 have been used for heterogeneous photocatalytic destruction of organic pollutants in waste water [19-22]. Dyes are the impotant class of organic water pollutants and therefore, many studies have been conducted on the photodegradation [23]. Methylene blue is one of the stable dyes extensibly used in textile industry, and is resistant to biodegradation.

Thus in the present work BSA is used as capping agent for the synthesis of CdS nanoparticles at 700C temperature. We have also explored the phocatalytic properties of synthesized BSA capped CdS nanoparticles for the degradation of methylene blue in presence of sunlight and light source.

2. Experimental Synthesis of cadmium sulphide nanoparticles Cadmium sulfide nanoparticles were prepared in aqueous phase at temperature range of

700C by using BSA as the capping agent. In a typical procedure, 10 ml of aqueous BSA (15 x 10-4

g ml-1) was taken in a round bottom glass flask. To this solution 0.1 M CdSO4 (50 ml), 0.1 M CH3 COOH (5 ml) was added with constant stirring. This mixture was stirred at room temperature for 15 minutes. Then 0.1 M Na2S solution by added drop wise with continuous stirring to the above mixture. The resulting solution was kept on magnetic stirrer for three hours at 700C. After three hours orange coloured solution was obtained. This solution was centrifuged at rate of 10000 RPM for 15 minutes on cooling. The precipitates obtained were washed several times using methanol and distilled water to remove the impurities. Finally the wet precipitates were dried in hot air oven at 500C for 24 hours.

Characterization The phase composition of the nanoparticles were determined by using X- ray

diffractometer (Panalytical S X. Pert Pro) using CuKα radiation. The morphology was taken with a transmission electron microscope (Hitachi TEM System).Thermal analyses were determined with Mettler Toledo (DSC-851E). FTIR analysis was done using Infrared spectrophotometer (Perkin Elmer Spectrum 400). The concentrations of dye were determined using UV-Visible spectrophotometer (Systronics 117).

Photocatalytic activity The photocalatytic activities of the CdS nanoparticles were carried out in a glass reactor of

100 ml capacity for degrading Methylene blue (MB) in water solution. A certain initial concentration of MB dye and the 0.5 gram of photocatalyst were taken in a reactor. This solution was stirred for half an hour in a dark. The resulted concentration was taken as initial concentration of MB. After exposure to the visible sunlight and sodium lamp source the dye concentrations were determined at different time for kinetic analysis. The light from the visible and sodium lamp

398

source were passed to the samples mixture through the glass filter. During the degradation study the samples were collected at regular interval, centrifuged to remove the catalyst portion prior to analysis. The supernatant solution was analyzed for dye concentrations by UV-visible spectrophotometer at wavelength of 653 nm.

Gel electrophoresis The polarity of the BSA capped nanoparticles was determined by gel electrophoresis using

tris-HCl buffer as a gel running medium with pH 7. For this purpose, 1% aqueous agarose solution was first brought to the boil in a microwave and then ethidium bromide dye was added in the boiled solution. This solution was left in the gel plate to harden. Wells were made in the gel plate with the help of comb. Then, 20 microlitre of colloidal CdS aqueous suspension made in acetic acid was loaded in the gel wells using methylene blue as staining agent. The direct voltage of 90 V was applied for 30 mints to determine the movement of nanoparticles.

3. Results and discussion Fig. 1 shows the X- ray diffraction pattern of the CdS nanoparticles. The results obtained

are very well matched with standard published data (JCPDS 10-454). The nanoparticles synthesized have good crystallinity and they are in the cubic form (zincblende phase) as all the peaks are prominent. The XRD patterns exhibits prominent broad peaks at 2θ values of 24.94, 47.85 and 51.92. These results are in agreement with 111, 220 and 311 planes. The intensity of the (111) is much higher than that of (220). Average particle size was found from XRD measurement value of FWHM using Debye- Sherrer formula [24]. The Peak broading in the XRD pattern indicates that small nanocrystals are present in the sample.

Scherrer equation (D) = Kλ/(βcosθ) Where K is constant (0.9), λ is the wavelength (λ= 1.5418 A0), β is the full width at the

half maximum of the line and θ is the diffraction angle. The average particle size of CdS nanoparticles were found in the range of 3.1 to 3.8 nm according to Debye- Scherrer formula.

The following fundamental reaction has been observed for the preparation of CdS nanoparticles CdSO4 + Na2S → CdS + Na2SO4

Fig. 1 XRD pattern of CdS nanoparticles

BSA capped CdS nanoparticles morphology are observed using TEM at different magnifications as shown in Fig. 2 (a-d). It is revealed from the TEM study that the BSA capped

399

BSA capped CdS nanoparticles morphology are observed using TEM at different

magnifications as shown in Fig. 2 (a-d). It is revealed from the TEM study that the BSA capped CdS nanoparticles show the spherical morphology and their average sizes are less than 4 nm which is consistent with XRD results. Further, TEM study shows the smooth morphologies apparently because of predominant growth of CdS nanoparticles capped with BSA.

Fig. 3 shows the results of thermogravimetric analyses (TGA) of CdS nanoparticles. The TGA analyses shows a weight loss of 16.583 % sharply in the range of 800 – 8450 C. TGA analyses indicate that BSA capped CdS nanoparticles are stable upto 8000 C.

Fig. 2 (a-d) Transmission electron microscopy images of BSA capped CdS nanoparticles at different magnifications

400

Fig. 3 TGA curve for the CdS nanoparticles obtained.

FTIR measurements (Fig. 4) have been made in the wave number range 400 cm-1 to 4000

cm-1. From the Figure it is revealed that the strong absorption bands at 616.47 cm-1 and 756.72 cm-

1 correspond to Cd-S stretching [25]. The IR peaks at 3411.58, 3041.37, 1654.00, and 1530.66 cm-

1 are assigned to the stretching vibration of –OH, amide A (mainly –NH stretching vibration), amide (mainly C=O stretching vibrations), and amide (the coupling of bending vibrate of N–H and stretching vibrate of C–N) bands, respectively [26]. These results clearly reveal that the nanoparticles are coated with BSA.

Preliminary studies on the photocatalytic properties of the CdS nanoparticles powders were made on methylene blue dye degradation under visible sunlight and sodium lamp radiation. The synthesized CdS nanoparticles was dispersed in aqueous solution of methylene blue dye and was irradiated with visible sunlight and sodium lamp in a reactor while the suspension was kept under stirring. The degradation of the dye was monitored at different time intervals using UV–Visible spectrophotometer.

401

Fig. 4 FTIR spectra of CdS nanoparticles.

Figs. 5 - 7 and Tables 1 - 2 shows the absorbance characteristics of methylene blue at different time intervals in visible sunlight and sodium lamp irradiations. It has been observed that from the figures that there is considerable degradation of the dye after exposure to about 3 hours. It was observed that concentration of methylene blue is reduced to about 25% of its initial value after exposure to UV radiation for about 3 hours. The photocatalytic activity of CdS nanoparticles for degradation of the methylene blue dye is more in presence of visible sunlight than sodium lamp irradiations.

It is concluded from the absorbance of dye before and after radiation at regular intervals that with increase in reaction time the photocatalytic activity of CdS nanoparticles increases. The CdS nanoparticles are able to decompose methylene blue dye upto 70% and 65% in two hours in the presence of visible sunlight and sodium lamp respectively. Thus BSA capped CdS nanoparticles can effectively be used as photocatalysts in the treatment of wastewater effluents and degradation of absorbed dyes.

Table 1. Absorbance of MB by CdS nanoparticles in different time at wavelength 653 nm in sodium lamp

Sr. No. Degradation time Absorbance A/A0 1. 1 hr 1.938 0.713

2. 2 hr 1.180 0.434 3. 3 hr 0.995 0.366

4. 4 hr 0.782 0.288 5. 5 hr 0.640 0.235 6. 6 hr 0.519 0.191 7. 7 hr 0.435 0.160

Methylene blue Absorbance (A0) is 2.715 Table 2. Absorbance of MB by CdS nanoparticles in different time at wavelength 653 nm in visible sunlight

402

Sr. No. Degradation time Absorbance A/A0

1. 1 hr 1.657 0.611

2. 2 hr 0.980 0.361

3. 3 hr 0.756 0.278

4. 4 hr 0.680 0.250

5. 5 hr 0.598 0.220

6. 6 hr 0.472 0.174

7. 7 hr 0.395 0.145

Methylene blue Absorbance (A0) is 2.710

Fig. 5 Degradation of methylene blue with photocatalyst under visible sunlight and sodium lamp radiations

Fig. 6 Degradation of methylene blue with photocatalyst under visible sunlight radiations.

A = Sodium lamp source

B = Visible sunlight

A

B

Irradiation time (hrs)

Abs.


A/A0

403

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

1 2 3 4 5 6

Fig. 7 Degradation of methylene blue with photocatalyst under sodium lamp radiations.

The scheme of CdS formation in the BSA solution is illustrated in Fig.8. Firstly, Cd2+ forms complex with BSA when CdSO4 is added to BSA solution. Secondly, when Na2S is added into the solution, the S2- combines with Cd2+ cooperated by BSA to form CdS. Finally, some CdS absorb on or bond to BSA molecules and form large CdS capped BSA nanoparticles.

The Gel electrophoresis determines the polarity of BSA capped CdS nanoparticles. It was observed from the gel electrophoresis study that CdS nanoparticles show a displacement towards the positively charged electrode under the applied potential, suggesting that the surface of BSA capped nanoparticles is predominantly negatively charged.

4. Conclusion The CdS nanoparticles were successfully synthesized by using BSA as the stabilizing

reagent at 700 C. This method is fast, inexpensive, producing high yield and requires neither complex apparatus nor a long reaction time. The CdS obtained are approximately cubic, with a size distribution from 3.1 to 3.8 nm in diameter. Further the results from XRD and SEM also confirm the nanocrystal nature of synthesized CdS. The synthesized CdS nanoparticles have successfully used for degradation of methylene dye in presence of visible sunlight and sodium lamp radiations. These protein-assisted synthesized CdS nanomaterials have a great potential application in photocatalysis, biomedical engineering and microelectronics.

Acknowledgement


A/A0

BSA

Cd 2+

S 2-

Fig. 7 Scheme of CdS nanoparticle formation

404

Authors are grateful to the Vice Chancellor of Shoolini University of Biotechnology and Management Sciences for providing laboratory and financial support to carry out the scanning from Panjab University, Chandigarh.

References

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Styrene–tin (IV) phosphate nanocomposite for photocatalyticdegradation of organic dye in presence of visible light

Bhim Singh Rathore a,b, Deepak Pathania a,⇑a School of Chemistry, Shoolini University, Solan 173 212, Himachal Pradesh, Indiab Department of Chemistry, Government P.G. College, Solan 173 212, Himachal Pradesh, India


Article history:Received 23 January 2014Received in revised form 25 March 2014Accepted 26 March 2014Available online 16 April 2014

Keywords:StyreneNanocompositeIon exchange capacityHeterogeneousPhotocatalysis

a b s t r a c t

Styrene–tin (IV) phosphate nanocomposite (ST/TPNC) ion exchanger was used as efficient photocatalystfor the degradation of methylene blue dye from aqueous system in the presence of solar light. ST/TPNCexhibited a high efficiency in heterogeneous photocatalytic process for the removal of MB from the watersystem. The degradation efficiency after 2 h illumination was 80%. The degradation of MB follows thepseudo-first-order kinetics with rate constant 0.00702 min�1. The nanocomposite ion exchanger wasexplored for its ion exchange capacity, pH titration, elution behavior, elution concentration and distribu-tion coefficient (Kd). ST/TPNC exhibited a higher ion exchange capacity (1.83 meg/g) compared to its inor-ganic counterpart (0.55 meg/g). ST/TPNC was characterized using some techniques such as Fouriertransform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), scanning electronmicroscopy (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD) and thermogravi-metric analysis (TGA).

� 2014 Elsevier B.V. All rights reserved.

1. Introduction

Ion exchangers have played a significant role in the growth anddevelopment of mankind. The ion exchangers have been exten-sively used for water treatment, pollution control, antibiotic puri-fication and separation of radioisotopes [1–3]. The ion exchangeris one of the most important and cost effective material for wastewater treatment [4–7]. An interest has arisen for the growth ofinorganic ion exchangers may be due to their convenience indiverse fields such as excellent thermal stability, resistivitytowards radiation fields and selectivity for ionic species [8–11].The basic constraints allied with the inorganic ion exchangers werelow mechanical and chemical stability. Moreover, they have beenobtained in the form of fine powder which made them unsuitablefor column process [12]. However, the organic ion exchangers wasnot used as an alternative due to their low pollutant removalcapacity at high temperature and less stability in high radiationfield [13,14].

Composite ion exchangers have been preferred over organic andinorganic ion exchangers as they overcome the major drawbacksassociated with both later. They have been prepared by the combi-nation of organic monomer or polymer and matrix of inorganic

part by maintaining the superior properties of both the ingredientsand thus enhancing the applicability of material. The compositeion exchangers have better chemical, mechanical, thermal andradiation stability with enhanced reproducibility [15–18]. Thecomposite materials due to multifunctionality, provided an exten-sive range of fascinating properties such as optical activity [19,20],catalytic activity [21] and environmental stability [22–24]. Theenhanced performance of the composite material was due to theincreased conductivity and surface area attributed from the inte-gration of metal nanoparticles in the material [25].

Recently, due to increasing population and rapid industrializa-tion, water pollution has become a major issue. The textile indus-tries discharge their dye effluents into the water bodies whichaffect the physical and chemical nature of natural water and makesit unfit for use. The dyes used in textile industries have complexstructure and most of them are mutagenic and carcinogenic tohuman beings [26]. Methylene blue (C16H18�N3SCl) is a blue col-ored powder which is water soluble and causes different problemsin humans such as nausea, haemolysis, hypertension and distressin respiration [17]. Several classical and conventional methodshave been used to remove the organic contamination fromeffluents but are not reliable and effective. The commonly usedtechniques such as coagulation, microbial degradation, chemicaloxidation, adsorption and photocatalysis have been explored forthe removal of organic pollutants from the aqueous system

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⇑ Corresponding author. Tel.: +91 9805440648.E-mail address: [email protected] (D. Pathania).

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[27,28]. Among these techniques, photocatalysis is the most effi-cient and consistent method for the degradation of a large varietyof organic dyes due to their simplicity, fast degradation and nongeneration of toxic materials [29]. Several photocatalytic materialssuch as ZnO-polyaniline, adsorbents like activated carbon, glassfibers, fly ash, sand, peanut hull, chitosan-g-poly (acrylic acid)/montmorillonite nanocomposite, natural phosphate etc. have beenused for the removal of different toxic waste [30–34]. The varioustypes of nanoparticles such as TiO2, SnO2, ZnO, ZrO2, SrTiO3, CdSand Bi2O3/Cu2O, Fe2O3 have been investigated as effective photo-catalysts for the degradation of organic pollutants [35,36]. How-ever, the composite ion exchangers with nanoscale dimensionshave attracted a great concern due to their varied applications indifferent fields. The advantage of heterogeneous catalysis overother processes is the easy and safe recovery of adsorbent andadsorbate by which secondary pollution can be avoided.

The composite ion exchangers exhibit a high efficiency in heter-ogeneous photocatalytic process and hence have drawn the atten-tion of scientists [37,38]. The photogenerated electron–hole pairsdiffuse to the nanoparticle surface before recombination to initiatea chain of photochemical reactions [39,40]. Photocatalytic processresulted in the oxidation–reduction and finally the degradation of awide variety of organic pollutants through their interaction withphoto generated holes or reactive oxygen species, such as �OH�

and �O2� radicals. The advanced oxidation process initiated by pho-

tocatalytic degradation has offer a better solution for decoloriza-tion, breakdown and mineralization of dyes [35]. Styrene basedion exchangers have been recorded cost effective, easily process-able, renewable and excellent material for remedial applications[41,42]. Polymer based nanocomposite have been used as excellentphotocatalyst as the polymer on the surface of the catalyst help totransfer the photogenerated electrons and holes and prevents nonradiative recombination of electrons and holes at surface [43].

In this work, the synthesis, ion exchange behavior, characteriza-tion and analytical properties of ST/TPNC ion exchanger have beenstudied. ST/TPNC ion exchanger has been explored for the photo-catalytic degradation of methylene blue dye from aqueous systemin presence of solar light.

2. Materials and method

2.1. Reagents and instruments

Tin (VI) chloride (E-Merck, India), dihydrogen phosphate (CDH Pvt. Ltd., India),styrene (Sigma–Aldrich, India), sodium nitrate (Loba Chemia, India), sodium chlo-ride (Rankem, India) Sodium hydroxide (Qualigens, India) were the main reagentsused for synthesis and analysis. All reagents and chemicals were of analytical gradeand used as received without further purification. Double distilled water was usedfor preparation and all dilutions. The instruments were used for the analyticalstudies and characterization includes X-ray diffractometer (X’pert Pro Analytical,Netherlands), Fourier transform infrared (FTIR) spectrophotometer (PerkinSpectrum-400), scanning electron microscope with energy-dispersive X-ray (JEOL,JSM-6610LL, Japan), transmission electron microscope (Hitachi H7500 model,Germany), UV–visible spectrophotometer (Shimadzu, Japan), thermogravimetryanalyses (TGA) (Shimadzu thermal analyser TGA50 model-Japan), an electronicvalance (Sartorius, Japan), digital pH meter (Elico LI10 model, India), muffle furnace(MSW-275, India), magnetic stirrer and digital oven.

2.2. Synthesis of styrene–tin (IV) phosphate nanocomposite (ST/TPNC) ion exchanger

A simple and ambient sol–gel method was used for the synthesis of styrene–tin(IV) phosphate nanocomposite ion exchanger (ST/TPNC). The synthesis of nanocom-posite ion exchanger has been carried out in two stages. In the first stage, inorganicprecipitates of tin (IV) phosphate (TP) were prepared by mixing sodium dihydrogenphosphate (0.1 M) and tin (IV) chloride (0.1 M) in 1:1 volume ratio with constantstirring at room temperature. 1 M HNO3 was added to maintain the pH of the mix-ture solution between 0 and 1. The resultant slurry containing the precipitates of tin(IV) phosphate was stirred for 1 h. In the next step, styrene (ST) solution was pre-pared in ethyl alcohol and added to above precipitates of tin (IV) phosphate withcontinuous stirring. The resultant white precipitates were kept for digestion for24 h with occasional stirring. Then the supernatant liquid was decanted, precipi-

tates were filtered, washed with double distilled water and dried at 50 �C temper-ature. The dried precipitates of ST/TPNC were cracked into small granules ofuniform size and converted into H+ form by treating with 0.1 M HNO3 for 24 h withrandom shaking. The precipitates were then filtered and washed several times withdouble distilled water in order to remove any excess of acid sticking to the particles.The ST/TPNC obtained was dried at 50 �C in a hot air oven. Number of samples of ST/TPNC was synthesized by varying the concentration of styrene (Table 1).

2.3. Ion exchange capacity (IEC) and effect of temperature on IEC

The ion exchange capacity of ST/TPNC ion exchanger was determined by stan-dard column process. In this process, 1.0 g dry mass of ST/TPNC ion exchanger in H+

form was placed in a glass column supported with glass wool support at bottom.The complete elution of H+ ions from the composite ion exchanger column was car-ried out by passing 1 M solution of NaCl. The flow rate of the effluent was kept at0.5 ml min�1. The effluent was collected and titrated against standard solution of0.1 M NaOH. The H+ ions released from the composite material were calculatedas per the formula discussed in the literature [44]. Based on the Na+ ion exchangecapacity and percentage yield the sample-3 was selected for further detailedstudies.

IEC ¼ N � VW

mg=g ð1Þ

where IEC is the ion exchange capacity, N and V are normality and volume (ml) ofNaOH respectively, W is the amount (mg) of ST/TPNC. The effect of temperatureon ion exchange capacity of ST/TPNC was studied by heating 1.0 g of material inH+ form at different temperatures for 1 h in digital muffle furnace. After cooling atroom temperature, the ion exchange capacity was determined by column process.

2.4. Effect of eluent concentration and elution behavior

To determine the optimum concentration of eluent for the complete elution ofH+ ions, a fixed volume (250 ml) of NaNO3 solutions of different concentrationswere passed through a column, containing 1.0 g of ST/TPNC ion exchange materialin H+ form with a flow rate of 0.5 ml min�1. 1 M NaNO3 was used for completeremoval of H+ ions from the column of ST/TPNC ion exchanger. The effluent was col-lected in 10 ml fractions at flow rate of 0.5 ml min�1. The collected fractions weretitrated against standard NaOH solution.

2.5. pH titration study

Topper and Pepper method was used to perform the pH titrations study of ST/TPNC ion exchanger [45]. In this method, 0.5 g of nanocomposite ion exchanger inH+ form was taken in several conical flasks, followed by the addition of 0.1 Msolution of alkali chloride and their hydroxide in different volume ratio. The finalvolume was maintained at 50 ml in each flask. The solutions were kept for equilib-rium and pH of each solution was recorded after each 24 h.

2.6. Distribution studies (Kd)

0.3 g of dried samples of ST/TPNC ion exchanger in H+ form were equilibratedwith 20 ml of different metal ions solutions and kept for 24 h at room temperaturewith random shaking. The concentration of metal ions in the solution before andafter equilibrium was determined by standard EDTA method and atomic absorptionspectrophotometer (AAS) [46,47]. The distribution coefficient (Kd) of different metalions were calculated using the formula as:

Kd ¼I � F

F� V

MmL g�1 ð2Þ

where I (g/l) and F (g/l) are the initial and final concentration of the metal ions insolution respectively. V is the volume of the solution (ml) and M is the amount (g)of ST/TPNC.

2.7. Fourier transforms infrared (FTIR) and X-ray diffraction (XRD) analysis

Fourier transforms infrared studies of ST/TPNC ion exchanger was performed byKBr disc method at room temperature. The ion exchanger sample in H+ form wasthoroughly mixed with KBr to form a fine powder. The transparent disc of standarddiameter was formed by applying the pressure. FTIR absorption spectrum wasrecorded in the region from 400 to 4000 cm�1. X-ray diffraction pattern of the nano-composite ion exchanger material was recorded using X’pert Pro Analytical diffrac-tometer with Cu Ka radiations (k = 1.5418 Å).

2.8. Scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) studies

The electron microphotographs of ST/TPNC nanocomposite ion exchanger wererecorded using scanning electron microscopy. The energy-dispersive X-rayequipped with scanning electron microscope was used to know the elemental com-position of the material.

106 B.S. Rathore, D. Pathania / Journal of Alloys and Compounds 606 (2014) 105–111

2.9. Transmission electron microscopy (TEM) and thermal (TGA/DTA) analysis

Transmission electron microscopy (TEM) studies were carried out to determinethe particle size of ST/TPNC nanocomposite ion exchanger. The suspension of com-posite material was prepared in ethanol onto a carbon copper grid. Thermal analysiswas determined by heating the nanocomposite material up to 700 �C at a constantrate of 10 �C per minute in nitrogen atmosphere using thermogravimetry analyser.

2.10. Photocatalytic studies

The photocatalytic activity of tin (IV) phosphate (TP) and styrene–tin (IV) phos-phate nanocomposite (ST/TPNC) were explored simultaneously for the degradationof methylene blue dye in the presence of solar light. A double walled Pyrex glasschamber jacketed with thermostatic water circulation apparatus was used to per-formed the photocatalytic studies [48,49]. In this process, 100 mg sample of eachST/TPNC in H+ form and TP were taken separately into 2 � 10�5 M solution of meth-ylene blue (MB) dye at constant temperature (30 �C ± 1). Magnetic stirrer was usedfor the controlled stirring of the solution. The above composed slurry of the dyesolution and catalysts suspension was stirred and placed in dark to attain theadsorption–desorption equilibrium. There after the slurry was exposed to naturalsolar light radiations for further photocatalysis. 3 ml of the solution was withdrawnin every time and centrifuged to separate the catalyst particles. The absorbance wasrecorded at 662 nm using double beam spectrophotometer and the kinetics of MBdegradation was studied. The percentage degradation of MB dye was calculatedusing the formula as [50]:

% Degradation ¼ Ce � Ct

Ce� 100 ð3Þ

where Ce and Ct are the concentrations of dye at equilibrium and at time t.


3.1. Physico-chemical properties

Various samples of styrene–tin (IV) phosphate nanocomposite(ST/TPNC) ion exchanger have been synthesized by the incorpora-

tion of different volume by volume ratio of styrene into the inor-ganic matrices of tin (IV) phosphate (TP). The highest ionexchange capacity ST/TPNC was recorded for sample number 3(S-3) as compared to all other samples (Table 1) hence chosenfor detailed analytical and characterization studies. ST/TPNCshowed much higher value of ion exchange capacity (1.83 meq/g)than its inorganic counterpart (0.55 meq/g). The increase in theion exchange capacity of ST/TPNC ion exchanger may be due tothe binding of styrene (ST) molecules with inorganic (TP) compo-nents [51]. Moreover, the organic part in the composite ionexchanger enhanced the mechanical properties and surface areaby providing more exchanging sites onto inorganic counterpart[24].

The effect of temperature on the ion exchange capacity of thenanocomposite ion exchanger has been shown in Table 2. Thedecrease in ion exchange capacity was observed with temperaturemay be due the decomposition of the organic part of the nanocom-posite material with increase in temperature. Thermal stability ofcomposite material was established by the retention of the ionexchange capacity to about 61.5% of the initial value up to 300 �C.

Table 1Condition of synthesis and ion exchange capacity of different samples of ST/TPNC.

Sample A (mol L�1) B (mol L�1) Mixingratio(V/V)

C (%) pH Appearanceof driedbeads

IEC(meq/g)

S-1 0.1 0.1 1:1 0 0.78 White 0.55S-2 0.1 0.1 1:1 5 0.76 White 1.67S-3 0.1 0.1 1:1 10 0.75 White 1.83S-4 0.1 0.1 1:1 20 0.76 White 0.94S-5 0.1 0.1 1:1 30 0.78 White 0.82S-6 0.1 0.1 1:1 40 0.75 White 0.75S-6 0.1 0.1 1:1 50 0.76 White 0.61

A – tin (IV) chloride, B – sodium dihydrogen phosphate, C – styrene (25 ml of eth-anol solution).

Table 2Effect of temperature on ion-exchange capacity of ST/TPNC.

Serialno.

Heatingtemp.(�C)

Appearance Weightloss (%)

Na+ ionexchangecapacity(meq g�1)

Retentionof IEC (%)

1. 50 White Nil 1.83 1002. 100 White 13.32 1.63 89.073. 150 Light

brown18.02 1.54 84.15

4. 200 Lightbrown

21.01 1.28 69.94

5. 250 Lightbrown

21.45 1.21 66.12

6. 300 Lightbrown

22.88 1.12 61.20

7. 350 Lightbrown

24.23 0.70 38.28

8. 400 Lightbrown

24.82 0.65 35.51

Fig. 1. (a) Effect of eluent concentration. (b) Elution behavior and (c) pH titrationcurve of ST/TPNC ion exchanger.

B.S. Rathore, D. Pathania / Journal of Alloys and Compounds 606 (2014) 105–111 107

Effect of eluent concentration for maximum elution of H+ ionsfrom ST/TPNC ion exchanger was shown in Fig. 1a. It is evident thatthe minimum molar concentration of eluent (NaNO3) for maxi-mum elution of H+ ions from the 1 g of ST/TPNC ion exchangerwas found to be 1 M. Therefore, it is concluded that the elution ratewas governed by the concentration of the eluent [52].

The elution behavior of ST/TPNC (Fig. 1b) indicated that the elu-tion is very rapid at the beginning and only 120 ml of NaNO3 (1 M)was enough to release the maximum amount of H+ ions from thecomposite material.

The pH titration curve for ST/TPNC ion exchanger obtainedunder equilibrium conditions with NaOH–NaCl system was shown

Fig. 2. (a) FTIR spectrum ST/TPNC and (b) UV–Vis spectra of TP and ST/TPNC.

Fig. 3. Scanning electron micrographs of (a) TP and (b) ST/TPNC (c) transmission electron micrograph (TEM) of ST/TPNC and (d) energy-dispersive X-ray (EDX) spectrum ofST/TPNC.


in Fig. 1c. The results expressed the single inflation curve indicatedthe monofunctional nature of the composite ion exchanger. Thestrong cationic nature of the ion exchange material was expressedby the low pH of the solution when no OH� ions were added insolution.

The distribution coefficient studies (Kd) of ST/TPNC wereexplored for the removal of ten different metal ions in distilledwater. The sequence of selectivity for adsorption of different metalions onto ST/TPNC ion exchanger was observed as Cd2+ (541.9) >Pb2+ (499.5) > Mg2+ (464.8) > Zn2+ (282.2) > Co2+ (237.5) > Cu2+

(198.2) > Cr3+ (161.3) > Mn2+ (157.5) > Ni2+ (137.3) > Fe3+ (81.1).The composite ion exchanger was found selective for Cd2+ andPb2+ compared to other metal ions. Thus based on Kd value ST/TPNC ion exchanger can be used for the detection and removal ofCd2+ and Pb2+ ions from the polluted water.

3.2. Characterization techniques

The FTIR spectrum of styrene–tin (IV) phosphate nanocompos-ite ion exchanger was shown in Fig. 2a. The presence of a strongand broad band at 3432 cm�1 may be assigned to the interstitialwater molecules [53]. A sharp peak at 1637 cm�1 may be attrib-uted to H–O–H bending and signifies the strongly bonding of OHgroups in the matrix [54]. The bands at 1051 cm�1 and 543 cm�1

may be attributed due to the stretching and bending vibration ofphosphate groups [55].

Fig. 2b shows the absorption spectra of TP and ST/TPNC ionexchanger. The absorption spectra shoulders of bare TP and ST/TPNC are observed at around 300 and 305 nm, respectively. Thusthe higher visible absorption was recorded for ST/TPNC with a clearlong tail up to 650 nm.

Temp Cel700.0600.0500.0400.0300.0200.0100.0

DTA

uV

100.0

50.0

0.0

-50.0

-100.0

-150.0

-200.0

-250.0

-300.0

TG m

g

34.00

32.00

30.00

28.00

26.00

24.00

22.00

20.00

DTG

mg/

min

0.0

-20.0

-40.0

-60.0

-80.0

-100.0

-120.0

-140.0

-160.0

-180.0

Fig. 4. TGA-DTA curves of ST/TPNC.

Fig. 5. MB degradation onto ST/TPNC under different system: [MB] = 2 � 10�5 M, catalyst dose = 100 mg, pH = 5.66, time = 120 min, wave length = 662 nm. (a) Adsorption atdark. (b) Adsorption followed by photocatalysis and simultaneously photocatalysis. (c) Percentage degradation of MB onto ST/TPNC and TP.


The X-ray diffraction spectrum of ST/TPNC shows in the pres-ence of low intensity peaks which confirmed the semi-crystallinenature of the composite ion exchanger.

Scanning electron micrographs of TP and ST/TPNC were shownin Fig. 3a and b. The SEM result of ST/TPNC confirmed the morphol-ogy has changed after binding of styrene with inorganic constitu-ent in nanocomposite material.

Transmission electron micrograph of ST/TPNC was shown inFig. 3c. It is revealed that the average particles size ranged between22.8 and 42.2 nm. Thus the particles present in a nanocompositeion exchanger were in nanorange.

EDX spectrum of ST/TPNC was shown in Fig. 3d. The result con-firmed the presence of Sn, P, C and O in ST/TPNC. The presence of Cand O further confirmed the formation of organic–inorganic hybridmaterial. It was observed that tin and phosphorous are the maincomponents present in the composite material.

The thermogram of ST/TPNC ion exchanger was depicted inFig. 4. The continuous weight loss of 10.64% up to 305 �C wasrecorded may be attributed due to the loss of external and coordi-nated water and hydroxyl groups from the nanocomposite mate-rial [56]. The further weight loss between 415.7 and 479.5 �Cmay be due to the complete decomposition of organic part of thecomposite material. The additional weight loss above 479.5 �Cmay be due to the thermo-oxidative conversion of material tometal oxides.

3.3. Photocatalytic degradation of MB

The effect of photodegradation of MB onto ST/TPNC ion exchan-ger was subjected to three different reaction processes viz equilib-rium adsorption in dark, equilibrium adsorption followed byphotocatalysis and simultaneous adsorption and photocatalysisas shown in Fig. 5(a and b). On the irradiation of nanocompositesthe electrons from conduction band of nanocomposites (containingSn, P and styrene) are transferred to valence band giving rise elec-tron–hole pairs. The valence band holes react with surfacebounded H2O or OH� to produce hydroxyl radical (OH�). Inelectrons in conduction band reduce the molecular oxygen tosuperoxide radicals [33,57]. The free radicals so generated disruptthe conjugation in the adsorbed dye molecules and degraded thedye. It has been revealed that the capping polymer on the surfaceof the particles play an role on the transfer of the photogeneratedelectrons and holes and prevents non radiative recombination ofelectrons and holes on the surface [40]. The proposed mechanism

for the photocatalytic degradation of dye has been shown asfollows:

ST=TPNCþMB Dye$ ST=TPNC� Dye

ST=TPNC� Dyeþ hv! ST=TPNCðe� þ hþÞ � Dye

ST=TPNC ðhþÞ þH2O! ST=TPNCðOH�Þ þHþ

ST=TPNC ðhþÞ þ OH� ! ST=TPNC ðOH�Þ

ST=TPNC ðe�Þ þ O2 ! ST=TPNCðO��2 Þ

OH� þDye! Intermediate Product!Degraded Product of MB dye

O��2 þDye! Intermediate Product!Degraded Product of MB dye

The photodegradation of MB dye onto ST/TPNC was studiedunder three different reaction conditions viz equilibrium processin dark adsorption, equilibrium adsorption followed by photodeg-radation (A/P) and simultaneous adsorption and photocatalysis(A + P) as shown in Fig. 5a and b. For equilibrium process in darkadsorption and simultaneous adsorption and photocatalysis(A + P) the MB degradation within 80 min of irradiation was about36% and 55%, respectively. While for equilibrium adsorption fol-lowed by photodegradation (A/P) only 30% of degradation wasrecorded after 80 min. During equilibrium adsorption followed byphotodegradation, the catalyst particles were highly covered bydye molecules which cut off the sunlight thus result in poorer deg-radation MB. In simultaneous adsorption and photocatalytic degra-dation process, the amount of dye adsorbed onto compositepresented the adequate active sites to generate valence – bandholes and conduction band electrons [23]. Therefore, the adsorbeddye molecules has been degraded quickly in simultaneous photo-catalysis. The photocatalytic degradation of MB dye onto ST/TPNC(82%) was observed much higher as compared to TP (50%) within120 min of irradiation (Fig. 5c).

The rate of photocatalytic degradation of MB dye was deter-mined using pseudo-first-order kinetic model as follow [27]:

r ¼ � dCdt¼ kappt ð4Þ

On integrating the above equation, we get

ln Co=Ct ¼ kappt ð5Þ

where kappt is the apparent rate constant, Co is the concentrations ofdye before radiance and Ct is the concentration of dye at time t.

The plot of In Co/Ct vs irradiation time resulted in linear correla-tion with good precision as shown in Fig. 6. Thus the whole processof photodegradation of MB dye by using ST/TPNC ion exchangerfollows a pseudo-first-order kinetics with rate constantK = 0.00702 min�1 with R2 = 0.9977 [58]. The rate constant valueclearly indicated the fast and effective photodegradation of MBonto ST/TPNC.

4. Conclusion

ST/TPNC ion exchanger has been successfully synthesized bysimple method at 0–1 pH. The ion exchange capacity of ST/TPNCion exchanger was found higher compared to its inorganic counter-part. The nanocomposite cation exchanger was found thermallystable as it retained its ion exchange capacity at high temperature.FTIR results confirmed the formation of composite ion exchangematerial. TEM images indicated the particle size of the materialwas in the nanorange. ST/TPNC ion exchanger was explored forthe photocatalytic degradation of methylene blue dye in presence

Fig. 6. Pseudo-first-order kinetic graph for photodegradation of MB onto ST/TPNC.


of solar light. ST/TPNC was more effective for the degradation ofmethylene dye in simultaneous adsorption and photocatalytic pro-cess as compared to other processes. The kinetics studies inferredthat the degradation followed the pseudo-first-order kinetics.

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11

SMC Bulletin Vol. 4 (No. 3) December 2013

Photocatalytic Activity of Cellulose Acetate-tin (IV) Molybdate Nanocomposite in Solar Light

B.S. Rathore, Gaurav Sharma and Deepak Pathania* Department of Chemistry, Shoolini University, Solan, Himachal Pradesh (India) -173212

E-mail:[email protected]

AbstractCellulose acetate tin (IV) molybdate nanocomposite (CA/TMNC) has been synthesized by simple and efficient sol gel process. The nanocomposite was characterized using Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM) and X-ray diffraction (XRD). The CA/TMNC was explored for its photocatalytic activity for the degradation of methylene blue dye from aqueous solution. The photocatalytic degradation of methylene blue dye was studied for 120 min with irradiation at 660 nm wavelength. The dye degradation of 82% was recorded within 60 min of irradiation time. The photodegradation of MB dye using nanocomposite was fitted well in pseudo-first-order kinetics.

Keywords: Photocatalysis, Nanocomposite, Methylene blue.

1. IntroductionDue to fast industrialization, natural water has been

polluted continuously by the release of effluents. Various industries such as textile, paper, paints etc have been discharging heavy metals and chemicals continuously into water bodies. Such polluted water containing toxic and carcinogenic substances may cause adverse effect to the human health and creating immense threat to ecological system, if not treated properly before release into environment [1-3]. Due to the colorful nature of dyes they can be easily visualized. Dyes are synthetic origin and have complex aromatic molecular structure which makes them more stable and difficult to biodegrade. The dyes can decompose into carcinogenic aromatic amines under aerobic conditions which can cause serious health problems like allergy, dermatitis, skin irritation, cancer etc to animals and human beings. So the attempt has been made by researchers for the treatment of wastewater containing dyes at source before being discharged into water bodies.

A large number of conventional methods such as chemical precipitation, ion exchange, electrodialysis, ultra filtration, membrane separation, photodegradation, electrochemical oxidation etc. have been have been explored for the removal of organic pollutants [4-10]. However, conventional methods have not economically and environmentally feasible for the removal of the dyes and metal ions from polluted water. Adsorption is one of the most effective techniques among the methods reported for the degradation of pollutants due to its economically viable, technically feasible and environmentally acceptable [11-15].

Recently, organic- inorganic hybrid nanocomposite materials have received much attention because of high performance due to different integrated combinations [16]. Organic materials have many limitations such as decreased mechanical strength and less removal capacity at high temperature [17]. The inorganic materials have some limitations besides the advantages like good selectivity for metal ions, stability at high temperature and radiation fields [18]. Therefore, to overcome these limitations, organic-inorganic nanocomposite material has been introduced which were significantly used in environmental applications [19-26].

Now a day, a significant attention has been drawn for the synthesis of cellulose based nanocomposite material due to its superior properties such as low cost, high-volume application, easy processability, renewable nature and possibility of recycling [24].

Thus the present work deals with the synthesis of cellulose acetate-tin (IV) molybdate nanocomposite (CA/TPNC) ion exchanger by simple sol-gel method. The photocatalytic activity of CA/TPNC material was explored for the degradation of methylene blue (MB) dye. The synthesized composite material was characterized by transmission electron microscopy (TEM), Fourier transform infrared (FTIR) and X-ray diffractrometer. The photocatalytic degradation of MB was determined using ultraviolet visible spectroscopy.

2. Experimental

2.1 Reagents and instrumentsAll reagents used in this were of analytical grade.

The main reagents used were tin (IV) chloride, sodium


12

Fig. 1. FTIR spectrum of CA/TMNC.

dihydrogen phosphate (LobaChemia Pvt. Ltd., Mumbai, India), Formic acid (E Merck Ltd., India), cellulose acetate (CDH Pvt. Ltd., New Delhi, India). Double distilled water was used for dilution and preparation of required solution for synthesis. Absorbance of samples was recorded using UV-Visible spectrophotometer (Shimadzu UV-1601, Japan). A digital pH meter (Elico LI-10, India), FTIR spectrophotometer (Perkin Spectrum-400), X-ray diffractometer (X’pert Pro Analytical, Switzerland), Transmission electron microscopy (Hitachi, H7500, Germany), Muffle furnace (MSW-275, India) and water bath incubator shaker were used.

2.2 Preparation of cellulose acetate-tin(IV) molybdate nanocomposite (CA/TMNC)

Cellulose acetate-tin (IV) molybdate phosphate nanocomposite (CA/TMNC) material was synthesis using simple sol gel method as mentioned earlier [27,28]. In this process, firstly 0.1 M solution of tin (IV) chloride was mixed with 0.1M solution of molybdate phosphate in 1:1 ratio by volume with constant stirring for 1h at room temperature. The pH of the solution was adjusted to 0-1 with the help of 1M HNO3. The precipitates of tin (IV) molybdate were formed. Further, the gel of cellulose acetate (CA) was prepared in concentrated formic acid. The gel was added to the precipitates of tin (IV) molybdate solution and mixed thoroughly with constant stirring for 5h. The resulting mixture was kept for 24h at room temperature for digestion with random shaking. The supernatant liquid was removed and precipitates were filtered under suction. The precipitates were washed with distilled water

to remove the excess acid. The precipitates of CA/TMNC were dried at 50oC temperature for 12 h.

2.3 Photocatalytic activity of CA/TMNCThe photocatalytic reaction was performed by the

slurry type batch reactor method [29]. A double walled Pyrex vessel was used for experiment and temperature of the vessel was maintained to 30±0.3oC. For adsorption studies, a suspension consisting of catalyst (CA/TMNC) and dye solution was stirred and kept in dark to attain the equilibrium. Whereas, in case of photocatalytic experiment the suspension prepared from composite ion exchanger and dye was five minutes and exposed to natural solar light. At particular time intervals the solution was taken (3mL) and centrifuged to eliminate the composite ion exchanger particles. The concentration of dyes was detected using UV-Vis spectrophotometer at 662 nm wavelength. The degradation efficiency of dye was calculated as follow:

Where Co and Ct are the initial and instant concentration of methylene blue dye.

2.4 FTIR studiesThe FTIR analysis 10 mg of CA/TMNC was mixed

with 100 mg of KBr and grounded to a very fine powder. A transparent was formed by applying pressure. The FTIR spectrum was recorded between 400 and 4000 cm-1.

13


3. Results and discussionThe FTIR spectrum of CA/TMNC was shown in

Fig. 1. The broad peak at 3429 cm-1 may be attributed due to the O-H stretching vibration [30]. The peaks in the regions 597 cm-1 may be assigned to metal oxide groups. Absorption band at 1740 cm-1 corresponds to carbonyl of ester group in cellulose acetate. The peak at 1627 cm-1 was due to free water molecule (water of crystallization) and strongly bonded –OH group in the matrix. A sharp peak at 1375 cm-1 indicates deformation vibration of hydroxyl groups [31].

The absorption band at 1246 cm-1 may be due to the vibration associated in the skeletal ring of sugar monomers. The presence of characteristics peaks of CA and TM in the spectra clearly indicated the formation of CA/TM nanocomposite.

TEM image of CA/TMNC was shown in Fig. 2. The TEM results indicated homogeneous distribution of CA and TM particles in the composite. The darker portion represents CA wrapped TM while white portion corresponds to polymeric CA backbone. The average particles of 29 nm were observed from the TEM images.

The XRD pattern of CA/TMNC was shown in Fig. 3. The result shows weak intensity peak thereby suggested the amorphous nature of the nanocomposite.

3.1 Photocataytic activity of CA/TM NanocompositesThe photodegradation of methylene blue using CA/

TMNC, tin molybdate (TM) and cellulose acetate (CA)

Fig. 2. TEM photographs of CA/TMNC.

Transmission electron microscopy (TEM) studiesTransmission electron microphotograph of CA/

TMNC was recorded using Hitachi transmission electron microscope.

2.5 X-ray analysisThe X-ray diffraction pattern of the CA/TMNC was

recorded by X-ray diffractometer using CuKα radiation (λ = 1.5418Å).

Fig. 3. X-rays diffraction pattern of CA/TMNC


14

In the typical photodegradation reaction, the CA/TMNC was irradiated with solar light produced electron–hole pair (hvb+/e-CB). The conduction band electrons were transferred to catalyst surface. The conduction band electrons reduced the O2 and forms hydroxyl radicals. The highly oxidizing OH. radicals caused the degradation of MB dye.

CA/TMNC + hν → e- + h+

H2O + h+ → O H• + H+

O2 + e- → O2• -

O2• - + H+ → HO2•

2 HO2• → H2O2 + O2

H2O2 + O2• -

→ OH• + O2 + O

OH• + MB+ → degraded product

The excited electron from the photocatalyst conduction band enters into the molecular structure of MB and disrupts its conjugated system. The hole at the valence band generates OH• via reaction with water or OH−. The OH• was used for oxidation of organic compound as shown in Figure 5.

The rate of photocatalytic degradation of methylene blue dye was determined using pseudo-first –order kinetic model [25]:

CA/TM NC

V B

C B M B

M B

Degraded Products OF MB

e

e

e

h+

e- + O 2 O2*

h+ + H 2O

M B

OH*

OH*

OH*

OH*

Fig. 5 Scheme for photodegradation on MB using CA/TMNC

The rate of photocatalytic degradation of methylene blue dye was determined using pseudo-first

–order kinetic model [25]:


ln C0/Ct=Kappt

where kapp is the apparent rate constant, C0 is the concentrations of dye before illumination and

Ct is the concentration of dye at time t. The plot of ln Co/Ct vs irradiation time showed a linear

correlation which demonstrated that the photodegradation of MB dye using CA/TM NC followed

the pseudo-first-order kinetics (Figure 6) [25]. The correlation coefficient value R2 was observed

to 0.999 indicated the feasibility of the reaction. The value of rate constant k (0.01259 min-1) was

calculated from the slope of the plot.


ln C0/Ct=Kappt

Fig. 6 Photocatalytic degradation kinetics of methylene blue dyeFig. 4 Photodegradation of Methylene Blue onto CA/TMNC, TM and CA

Fig. 5 Scheme for photodegradation on MB using CA/TMNC

were investigated in presences of solar light. The results of the photodegradation of MB were shown in Figure 4. The decrease in the dye absorbance with time indicated that the dye was degraded in aqueous solution using nanocomposite. The maximum degradation of dye was recorded for CA/TMNC compared to TM and CA in presence of solar light. It has been observed that about 91% of dye was degraded in 120 minutes compared to 53 and 37% for TM and CA, respectively.


16

Gaurav Sharma is pursuing his Ph.D research under the supervision of Dr. Deepak Pathania at Shoolini University, Solan, HP. He is working as Assistant Professor, School of Chemistry, Shoolini University, Solan, Himachal Pradesh. He had obtained his M.Sc from Barkatullah Vishwavidyalaya, Bhopal, MP and M.Phil degree from Shoolini University, Solan, HP. He had published about 07 papers in journals of repute. His area of research includes analytical chemistry, nanocomposites, bimetallic nanoparticles, nanocomposite ion exchangers, environmental chemistry, water purification and drug delivery etc.

Bhim Singh Rathore is pursuing his Ph.D research under the supervision of Dr. Deepak Pathania at Shoolini University, Solan, HP. He is working as Associate Professor, Department of Chemistry, Government PG College, Solan, Himachal Pradesh. He is also Press Secretary, Him Science Congress Association, Himachal Pradesh. He had obtained his M.Sc and M.Phil degree from Himachal Pradesh University, Shimla. He had published about 10 papers in journals of repute. His area of research includes polymer based composites, nanocomposite ion exchangers, environmental chemistry, photocatalysis etc.

Deepak Pathania is Associate Professor, Department of Chemistry, Shoolini University Solan, Himachal Pradesh, India. He is also serving as founder President, Him Science Congress Association, Himachal Pradesh. He started his teaching career in 2001from NIT, Jalandhar, Punjab. He has served as Head Department of Applied Sciences and Humanities in 2008. He is members of different professional scientific societies. He had guided 4 Ph.D and 8 M.Phil students for their degree. Presently he is guiding 4 Ph.D and 2 M. Phil students. He had authorized six books in different areas of interest from believed publishers. He had about 80 publications to his credit. His area of research includes polymer based composites, nanocomposite ion exchangers, graft copolymerization, fiber reinforced composite, environmental chemistry, photocatalysis etc.

Documents

List of Papers Presented - INFLIBNETshodhganga.inflibnet.ac.in/bitstream/10603/24634/6/15...List of Papers Presented 1. Deepak Pathania, Sarita and B.S. Rathore , Synthesis, Characterization