Dye removal from aqueous solution using low cost adsorbent · commercially available dyes with over 7 x 10 5 of dyes produced annually worldwide [1 2]. Dye s are widely used in industries

INTERNATIONAL JOURNAL OF ENVIRONMENTAL SCIENCES Volume 1, No 7, 2011

© Copyright 2010 All rights reserved Integrated Publishing Association

Research article ISSN 0976 – 4402

Received on March 2011 Published on April 2011 1492

Dye removal from aqueous solution using low cost adsorbent Velmurugan .P 1 , Rathina kumar.V 2 , Dhinakaran.G 3

1 JRF, School of Civil Engineering, SASTRA University, Tamil Nadu, India 2 Assistant Professor, School of Civil Engineering, SASTRA University, Tamil Nadu, India 3 Professor, School of Civil Engineering, SASTRA University, Tamil nadu613 401, India

[email protected]

ABSTRACT

The use of cheap and ecofriendly adsorbents studied as an alternative substitution of activated carbon for removal of dyes from wastewater. Adsorbents prepared from orange peel, which is a domestic waste, successfully used to remove the methylene blue from an aqueous solution in a batch wise column. This study investigates the potential use of orange peel, pretreated with nominal treatment method, for removal of methylene blue from simulated wastewater. Treated orange peel used to adsorb methylene blue at varying dye concentration, adsorbent dosage, pH and contact time. Similar experiments conducted with some other low cost adsorbent such as banana peel, neem leaves and commercially available powdered activated carbon (PAC). The adsorption capacity of orange peels decreased in the order of methyl orange (MO) > methylene blue (MB) > Rhodamine B (RB) > Congo red (CR) > methyl violet (MV) > amido black 10B (AB). Removal efficiency of all the adsorbents is quite effective, but orange peel found to be very effective compared to other low cost adsorbent within the short period. The sorption data were then correlated with the freundlich and the langmuir adsorption isotherm models. In both isotherms exhibited a maximum K value in which indicates that the orange peel has greater affinity for methylene blue. The maximum color removal efficiencies of orange peel at dosage of 1.0g for time duration of 45 min found to be 99% of the dye from an aqueous solution of 12.32 ppm. From the study it is understood that pH, contact time and adsorbent dosage plays a vital role in removal of dye.

Keywords: Adsorbent, Methylene blue, pH, Orange peel, Neem leaves, Banana peel,

1 Introduction

Dyes are chemicals, which on binding with a material will give color to them. Dyes are ionic, aromatic organic compounds with structures including aryl rings, which have delocalized electron systems. The color of dye provided by the presence of a chromophore group. A chromophore is a radical configuration consisting of conjugated double bonds containing delocalized electrons. The Chromogen, which is the aromatic structure normally containing benzene, naphthalene or anthracene rings, is part of a chromogenchromophore structure along with an auxochrome. The presence of ionising groups known as auxochromes results in a much stronger alteration of the maximum absorption of the compound and provides a bonding affinity. Colored dye wastewater arises as a direct result of the production of the dye and because of its use in the textile and other industries. There are more than 100,000 commercially available dyes with over 7 x 10 5 of dyes produced annually worldwide [12]. Dyes are widely used in industries such as textile, rubber, paper, plastic, cosmetic etc. Among these various industries, textile ranks first in usage of dyes for coloration of fiber. The convectional biological treatment process is not very effective in treating a dyes wastewater, due to low biodegradation of dyes. It is usually treated by either physical or chemical

Dye removal from aqueous solution using low cost adsorbent

Velmurugan. P, Rathina kumar. V, Dhinakaran. G

International Journal of Environmental Sciences Volume 1 No.7, 2011

1493

processes. However, these processes were very expensive and could not be effectively used to treat the wide range of dyes waste [Grag et al, 2003].

The adsorption process is one of the effective methods for removal dyes from the waste effluent. The process of adsorption has an edge over the other methods due to its sludge free clean operation and completely removed dyes, even from the diluted solution. Activated carbon (powdered or granular) is the most widely used adsorbents because it has excellent adsorption efficiency for the organic compound. Nevertheless, commercially available activated carbon is very expensive. Furthermore, regeneration using solution produced small additional effluent while regeneration by refractory technique results in a 1015% loss of adsorbents and its uptake capacity [Shaobin Wang et al, 2005]. The sorption data have been correlated with adsorption isotherm to determine the efficiency of adsorption process. Numerous researchers worked earlier on variety of adsorpents as mentioned below. Wool Fiber and Cotton Fiber [Rasheed Khan et al, 2005], Banana pith [Namasivayam et al, 1993a,1993b], Biogas residual slurry [Namasivayam et al, 1992a], Carbonized coir pith [Namasivayam et al, 2001a], Coir pith [Namasivayam et al, 2001b,2002], Chitosan [Juang et al, 1996], Hardwood [Asfour et al, 1985], Mahogany sawdust, rice husk [Namasivayam et al,1992b], Parthenium hysterophorus [Rajeshwarisivaraj et al, 2002], Neem (Azadirachta Indica) husk [Alau et al, 2010], Rice husk [Singh et al, 2001], Rice husk [Guo et al, 2003], Silk cotton hull, coconut tree sawdust [Kadirvelu et al, 2003], Gypsum [Muhammad Rauf et al, 2009], Tuberose Sticks [Ahsan habib et al, 2006], Tamarind Fruit Shell[Papita Saha 2010].

2 Experimental Investigations

2.1 Preparation of the Adsorbent

Adsorbents like Orange Peel, Neem leaves and Banana peel collected from the local areas of Thanjavur District. The peels and leaves collected and dried at low temperature (<105˚C) for 48 hrs to remove moisture content. After drying process, peels were ground to fine powder and sieved through 600 µ size. The adsorbents used in the present research work prepared under Nominal Treatment only.

2.2 Dye solution preparation

The characteristics of the Methylene blue used for the present work is given in Table 1. An accurately weighed quantity of the dye dissolved in double distilled water to prepared stock solution (1000 ppm). Solution used in the experiment for the desired concentration obtained by successive dilutions. Dye concentration was determined by using absorbance values measured before and after the treatment, at 650 nm with Shimadzu UV Visible Spectrometer (Model : UV mini 1240). Experiments were carried out at initial pH value is 6.5 and was controlled by addition of sodium hydroxide or hydrochloric acid, physical characteristics of various adsorbents given in Table 2.

Table 1: Properties of Methylene Blue

Chemical formula C14H18N3SCl Molecular weight 319.85 g/mol Melting point 100 – 110 °C Type of dye Basic blue Boiling point Decomposes λmax 665 mm




1494

Table 2: Physical Properties of Adsorbents

2.3 Calibration of Methylene Blue

The synthetic dye sample calibrated in order to find out various optical densities at various concentrations. The calibrated results are very effective to identify the respective color removal capacities of various adsorbents Figure1 showing the graphical representation of Calibration of Methylene Blue.

Figure 1: Calibration of Methylene Blue.

Value No. Parameter

Orange Peel Neem Leaves

Banana Peel

Activeted Carbon

01. Moisture Content (%) 38.50 11.10 7.70 30.00

02. Ash Content (%) 17.80 4.30 5.60 30.00

03. Volatile Content (%) 43.70 84.60 86.70 40.00

04. Specific Gravity 3.22 2.85 3.13 1.83

05. Fineness Modulus 3.24 3.128 3.02 2.17

06. Particle size (mm) 0.150 0.186 0.200 0.002

07. Void ratio 0.75 0.75 0.36 0.50

08. Particle Density (g/cc) 1.44 0.56 0.92 1.90




1495

2.4 Effect of time on various adsorbents

In each adsorption experiment, 20 ml of dye solution of known concentration and pH was added to 0.1g of adsorbents in 250 ml round bottom flask at room temperature and the mixture was stirred on a rotary orbital shaker at 150 rpm. The sample withdrawn from the shaker at the pre determined time intervals for 10 minutes each. At the end of 10 min, the agitated sample taken from the shaker and tested for its optical density using the UVVisible Spectrophotometer. The corresponding Optical Density interpolated with the initial calibration values in order to find out color removal efficiency of the adsorbent. From the Comparative results, it is clearly known that, the effect of duration plays a very important role in adsorption process of color removal. All the adsorbents are quite effective, but Orange peel found to be very effective next to activated Carbon. The color removal efficiencies of the adsorbents have a break through at 60 minutes duration, in which there is no further color removal takes place. Orange Peel found to be very effective with color removing efficiency of 96%. The results of present study are compared with results of Papita Saha 2010, who has done experiments with Tamarind shell. It is inferred from the comparison that, upto the duration of 40 min, orange peel showed lesser efficiency and after 40 min it shows higher efficiency than the Tamarind shell. The comparative results of efficiency of various adsorbent with respect to time given in Figure 2. However, activated carbon performs well when compared to all these low cost adsorbents.

Figure 2: Comparative results of various adsorbents on to Effect of Time

2.5 Effect of adsorbent dosage on various adsorbents

20 ml of the stock solution of 1000 ppm taken and with varied amount (0.2, 0.4, 0.6, 0.8, 1 g) of adsorbent fed into the 250ml round bottom flask and kept for agitation at 150 rpm using rotary orbital shakers for the regular interval of 45 minutes. At the end, the agitated sample taken from the shaker and tested for its optical density using the UVVisible Spectrophotometer. The corresponding Optical Density interpolated with the initial calibration values in order to find out color removal efficiency of the adsorbent. From the Comparative results, it is clearly understood that the Effect of Adsorbent Dosage is also plays a very vital role in adsorption process for color removal. Among the three adsorbents, Orange




1496

peel found to be very effective next to Activated Carbon. Therefore, from the two parameters such as Effect of Time and Effect of Adsorbent dosage, Orange peel found to be an excellent adsorbent compared to Neem leaves and Banana Peel. The maximum color removal efficiencies of Orange peel, Neem leaves and Banana Peel at dosage of 1 g for a time duration of 45 minutes is found to be 98.76, 97.77 and 97.93 respectively Figure 3 Showing the graphical representation of comparative results various adsorbent with respect to adsorbent dosage.

Figure 3: Comparative results of various Adsorbents on to Effect of Adsorbent Dosage

2.6 Effect of pH on Orange Peel for Color Removal

In Order to find the effect of pH, series of experiments conducted at various pH values from 24 and 810 in acidic and alkaline conditions respectively. However, the initial pH of the stock solution prepared was 6.50 at 1000 ppm. The value of pH controlled by addition of sodium hydroxide or hydrochloric acid. For the present research, the stock solution of 20 ml taken and 0.1 g of adsorbent fed into round bottom flask and kept for rotary orbital shaker at 150 rpm. The sample withdrawn from the shaker at the pre determined time intervals for 10 minutes each. At the end of each 10 minutes the agitated sample is taken from the shaker and tested for its optical density using the UVVisible Spectrophotometer.

Effect of pH under acidic condition imparts a new color (greenish yellow) in which the respective optical density found to be more than 4.00, because of some acidic elements already present in the orange peel. Again some sample was analyzed at the pH of 4, the value of the optical density is slightly above the calibration value of the Methylene blue. Hence color removal under acidic condition using orange peel as an adsorbent found to be insignificant, where as for alkaline condition it is significant. Effect of pH and different dosage of adsorbent under alkaline conditions are depicted in Figures 4 and 5.




1497

Figure 4: Effect of pH under alkaline conditions at regular time interval.

Figure 5: Effect of pH under alkaline conditions at various adsorbent dosages

2.7 Column Study using Orange peel

The column tests carried out in a microglass column with inside diameter of 12.5 mm, length 750 mm with a capacity of 50 ml. By using column study burette found to be very economical and there is no external driven force applied to the system. Series of burettes operated in a parallel way and filled with 10 ml of adsorbent and 40 ml of adsorbate. A thin layer of very fine particles of sand of diameter of 0.7 mm with the depth of 50 mm placed at the bottom in order to remove the foreign and dust particles. Figure 6 shows experimental setup of column study.

Particle size plays a foremost role in adsorption process especially in the column studies and the particle size of the adsorbent is 0.6 mm. The effluent of the first column considered as the influent of the second column with time interval of 60 minutes each. The results are shown in Figure 7.

The effluent from the each burette was taken and measured for its optical density. In order to correct for any adsorption of color by the container, control experiments carried out without adsorbents. It was found that there was no adsorption by the container walls. Similarly same test were carried out by using the filling material and was found that no adsorption took place, and the entire column tests conducted at room temperature only.




1498

Figure 6: Series of column tests conducted using burettes

Figure 7: Efficiency of color removal using orange peel as adsorbent

3 RESULTS AND DISCUSSIONS

The study of isotherm data is important to find out the adsorption capacity of various adsorbents. In order to investigate the adsorption isotherm, two equilibrium isotherms were analyzed: Langmuir and Freundlich isotherms are used for fitting the experimental data in adsorption studies to understand the extent and degree of favorability of adsorption.

3.1 Freundlich Isotherm

The equilibrium adsorption isotherms are of fundamental importance in the design of adsorption systems. The equilibrium adsorption data could be satisfactory by the Freudlich isotherm

x/m = K.C 1/n

where x is the amount adsorbed per mass of adsorbent (m), Co is the initial concentration of the solution (ppm), C is the equilibrium concentration (ppm), and K and n are Freudlich




1499

constants. The constant K, partition coefficient in equilibrium is positively related to the extent of degree of adsorption, while then constant ‘n’ provides a rough estimation of the intensity of adsorption. A linear form of the Freundlich expression will yield the constants K and n hence:

log x/m = log K+1/n log C

The analysis and design of adsorption separation process require the relevant adsorption equilibrium, which is the most important piece of information in understanding the adsorption process. The adsorption isotherms are equilibrium equation and apply to condition resulting after the adsorbatecontaining phase has seen in contact with the adsorbent of sufficient time to reach equilibrium [Tan et al, 2010]. The adsorption capacity of any adsorbent may be determined by the used of an adsorption isotherm. Knowledge of adsorption capacity of an adsorbent material such as lignite enables the designer to develop treatment systems for particular adsorbate/adsorbent systems [Allen et al, 1989].

Freudlich constants were determined from the graphs plotted for log (X/M) in ordinate and log Ce in abscissa. Table 3 shows the Orange peel has the maximum K value followed by Banana Peel and Neem leaves. The higher value of K (0.775mg/g) indicates that Orange Peel have greater affinity for methylene blue compared with other adsorbents. The adsorption intention ‘n’ is found to 1.50, 0.612 and 1.273 for Orange peel, Neem leaves and Banana peel respectively. It is observed that all the adsorbents do not satisfy the condition of heterogeneity, i.e., 1<n<10. Only Orange Peel and Banana Peel satisfy those conditions.

Table 3: Freudlich Isotherm constants for Adsorbents Sl.No Name of the

Adsorbent Value of ‘n” K (mg/g) R 2

1. Orange Peel 1.50 0.775 0.6210 2. Neem leaves 0.612 0.327 0.8373 3. Banana Peel 1.273 0.635 0.6716 4. Activated Carbon 0.952 0.7276 0.8975

3.2 Langmuir Isotherm

The Langmuir model was developed based on the assumption of the formation of a monolayer of the absorbate species onto the surface of the adsorbent. It has also been assumed that the surface sites are completely energetically homogeneous. But in the true sense, the adsorbent surface is energetically homogeneous. The study of the Langmuir isotherm is essential in assessing the adsorption efficiency of the adsorbent. This study is also useful in optimizing the operating conditions for effective adsorption. In the respect, the Langmuir isotherm is important, though the restrictions and the limitations of this model have been well recognized.

The Langmuir and the arranged Langmuir equations are given below,

q = (Xmk C) / (1+kC)

Ce/Qe = 1/k.Xm + Ce/Xm

Where q is the amount of dye adsorbed per unit weight of the adsorbent, C is the Concentration of dye remaining in solution at equilibrium, Xm is the amount of dye adsorbed




1500

per unit weight of adsorbent in forming a complete monolayer on the surface and k is the constant related to the energy. By plotting Ce versus Ce/Qe, a curve is obtained which is linear at low equilibrium concentrations, followed by a curvature and with an asymptotic tendency to saturation corresponding to a monolayer covering.

Table 4: Langmuir Constants for various adsorbents Sl.No Name of the

Adsorbent a (l/mg) K (l/g) R 2

1. Orange Peel 0.00502 10,000 0.08368 2. Neem leaves 0.00903 3,333.33 0.5529 3. Banana Peel 0.00411 10,000 0.0769 4. Activated Carbon 0.00370 33,333.33 0.0402

From the Table 4 , the higher value of K (10,000) indicates that the amount of methylene blue per unit weight of adsorbent seem to significantly higher than Neem leaves, in which both orange peel and Banana peel have same values. Neem leaves is found to very nonlinear, this will normally occur after dye particles fill the available monolayer in the adsorbents. This nonlinearity may also be due to any primary expansion of adsorbent while will give way to a secondary or tertiary expansion which can occur at much reduced rates. From the results the higher value of K from Orange peel is found to be very effective followed by Banana peel and Neem leaves, which confirmes the result obtained from the Freudlich Isotherm that Orange peel has the maximum K value followed by Banana peel and Neem leaves. The plots showing results between log(X/M) and log (Ce) is given in Figure 8 for Freundlich Isotherm and between Ce/Qe and Ce is given in Figure 9 for Langmuir Isotherm.

Figure 8: Freudlich Isotherm using Orange Peel




1501

Figure 9: Langmuir Isotherm using Orange Peel

4 Conclusions

From the results of the present study, it is concluded that, the adsorption process is a very effective process for the decolorization of textile wastewater, as we can reach 97% decolorization in few minutes. There is a need to enhance the adsorption process effectively by varying parameters so as to bring down the values to permissible limits for wastewater before discharging it to the water environment. The removal of color from aqueous solutions and wastewaters using activated carbon and three low cost sorbent materials orange peel, neem leaves and banana peel was studied by studying the effect of time, adsorbent dosage and pH. A separate column study was conducted in which, flow was due to gravity. Two types of isotherms were investigated, namely the Langmuir and Freundlich isotherms.

The adsorption studies revealed that the optimum time adsorption of Orange Peel, Neem leaves and Banana peel was found to be 60 minutes and adsorbent dosage was 1 g for all the three adsorbents. The isotherm analysis revealed that orange peel prepared under nominal treatment was found to be very effective than the Neem leaves and Banana Peel. Adsorption was an effective process for decolorization of textile wastewaters. Although activated carbon was the most effective sorbent, other low cost sorbents could be used for color removal. The final choice of the sorbent is a matter of economics. Batch studies and column studies confirm that these low cost materials can be used as a substitute for high cost adsorbent.




1502

5 References

1. Saiful Azhar, S., Ghaniey Liew, A., Suhardy,D., Farizul Hafiz, K., Irfan Hatim, M.D. (2005). “Dye Removal from Aqueous Solution by using Adsorption on Treated Sugarcane Bagasse.” American Journal of Applied Sciences, 2(11), 14991503.

2. Grag, V.K., Raksh Kumar., Renuka Gupta. (2004). “Removal of malachite green dye from aqueous solution by adsorption using agroindustries waste: A case study of Phosopisceneraria.” Dyes & Pigments, 62(1), 110.

3. Grag, V.K., Renuka Gupta., Anu Bala yadav., Rakesh Kumar. (2003). “Dye removal from aqueous solution by adsorption on treated sawdust.” Bioresource Technology, 89(2), 121124.

4. Shaobin Wang., Boyjoo, Y., Choueib, A., Zhu, Z.H. (2005). “Removal of dyes from aqueous solution using fly ash and red mud.” Water Research, 39(1), 129138.

5. Rasheed Khan, A., Hajira Tahir., Fahim Uddin., Uzma Hameed. (2005). “Adsorption of Methylene Blue from aqueous Solution on the Surface of Wool Fiber and Cotton Fiber.”Journal of Applied Science and Environment Management , 9(2), 29 – 35.

6. Namasivayam, C., and Kanchana, N. (1993a). “Removal of Congo red from aqueous solution by waste banana pith.” Journal of Science and Technology, 1(1), 3342.

7. Namasivayam, C., N. Kanchana, N., Yamuna, R.C. (1993b). “Waste banana pith as adsorbent for the removal of RhodamineB from aqueous solution.” Waste Management, 13(1), 8995.

8. Namasivayam, C., Yamuna, R.C. (1992). “Removal of RhodamineB by biogas slurry from aqueous solutions.” Water Air and Soil Polluiont, 65(12), 133139.

9. Namasivayam, C., Radhika, R., Subha, S. (2001a). “Uptake of dyes by a promising locally available agricultural solid waste: coir pith.” Waste Management, 21(4), 381 387.

10. Namasivayam, C., Dinesh Kumar, M., Selvi, K., Ashruffunissa Begum, R., T. Vanathi, T., Yamuna, R.T. (2001b). “Waste coir pitha potential biomass for the treatment of dyeing wastewaters.” Biomass and Bioenergy, 21(6), 477483.

11. Namasivayam, C., Kavitha, D. (2002). “Removal of Congo Red from water by adsorption on to activated carbon prepared from coir pith, an agricultural solid waste.” Dyes Pigments, 54(1), 4758.

12. Juang, R.S., Tseng, R.L., Wu, F.C., Lin, S.J. (1996). “Use of chitin and chitosan in lobster shell wastes for color removal from aqueous solution.” Journal of Environmental Science and Health, Part A, 31(2), 325338.

13. Asfour, H.M., Fadali, O.A., Nassar, M.M., ElGeundi, M.S. (1985). “Equilibrium studies on adsorption of basic dyes on hardwood.” Journal of Chemical Technology and Biotechnology, 35(1), 2127.




1503

14. Namasivayam, C., Yamuna, R.T. (1992). “Removal of Congo red from aqueous solution by biogass slurry.” Journal of Chemical Technology and Biotechnology, 53(2), 153157.

15. Rajeshwarisivaraj, Subburam, V. 2002. “Activated parthenium carbon as an adsorbent for the removal of dyes and heavy metal ions from aqueous solution.” Bioresource Technology, 85(2), 205206.

16. Alau, K.K., Gimba, C.E., Kagbu, J.A. (2010). “Removal of Dyes from Aqueous Solution Using Neem (Azadirachta Indica) Husk as Activated Carbon.” Archives of Applied Science Research, 2(5), 456461.

17. Singh, D.K., Srivastava, N. (2001). “Basic dyes removal from wastewater by adsorption on rice husk carbon.” Indian Journal of Chemical Technology, 8(2), 133 139.

18. Guo, Y., Yang, S., Fu, W., Qi, J., Li, R., Wang, Z. (2003). “Adsorption of malachite green on micro and mesoporous rice husk based activated carbon.” Dyes & Pigments, 56(3), 219229.

19. Kadirvelu, K., Kavipriya, M., Karthika, C., Radhika, M., Vennilamani, N., Pattabhi, S. (2003). “Utilization of various agricultural wastes for activated carbon preparation and application for the removal of dyes and metals ions from aqueous solutions.” Bioresource Technology, 87(1), 129132.

20. Muhammad, Rauf, A., Shehadeh, I., Amal Ahmed, Ahmed AlZamly. (2009). “Removal of Methylene Blue from Aqueous Solution by Using Gypsum as a Low Cost Adsorbent.” World Academy of Science, Engineering and Technology, 55.

21. Ahsan habib, Zahidul Hasan, A.S.M. Shajedur Rahman A.M. Shafiqul Alam, (2006). “Tuberose Sticks as an Adsorbent in the Removal of Methylene Bluefrom Aqueous Solution.” Pakistan Journal of Analytical & Environmental Chemistry,7(2), 112 115.

22. Papita Saha, (2010). “Assessment on the Removal of Methylene Blue Dye using Tamarind Fruit Shell as Biosorbent.” Springer Science+Business Media B.V., 213, 287–299.

23. Tan,I.A.W., Hameed, B.H. (2010). “Adsorption studies of basic dye on activated carbon derived from oil palm empty fruit .bunch.” Journal of Applied Science, 10(21), 25652571.

24. Allen, S.J., Gorden Mckay, Khader, K.Y.H. (1989). “Equilibrium adsorption isotherm for basic dyes onto liqnite.” Jornal of Chemical Technology and Biotecnology, 45(4), 291302.

Documents

Dye removal from aqueous solution using low cost adsorbent · commercially available dyes with over 7 x 10 5 of dyes produced annually worldwide [1 2]. Dye s are widely used in industries