Research Article Batch Sorption Experiments: Langmuir and ...downloads.hindawi.com/archive/2013/375830.pdf · Batch Experiments and Adsorption Isotherms. Sorp-tion studies were conducted

Hindawi Publishing CorporationJournal of ThermodynamicsVolume 2013 Article ID 375830 6 pageshttpdxdoiorg1011552013375830

Research ArticleBatch Sorption Experiments Langmuir and Freundlich IsothermStudies for the Adsorption of Textile Metal Ions onto Teff Straw(Eragrostis tef ) Agricultural Waste

Mulu Berhe Desta

Department of Chemistry College of Natural and Computational Sciences Mekelle University PO Box 231 Mekelle Ethiopia

Correspondence should be addressed to Mulu Berhe Desta mullerdestayahoocom

Received 20 February 2013 Accepted 2 August 2013

Academic Editor Angelo Lucia

Copyright copy 2013 Mulu Berhe Desta This is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

Adsorption of heavy metals (Cr Cd Pb Ni and Cu) onto Activated Teff Straw (ATS) has been studied using batch-adsorptiontechniques This study was carried out to examine the adsorption capacity of the low-cost adsorbent ATS for the removal of heavymetals from textile effluents The influence of contact time pH Temperature and adsorbent dose on the adsorption process wasalso studied Results revealed that adsorption rate initially increased rapidly and the optimal removal efficiency was reached withinabout 1 hour Further increase in contact time did not show significant change in equilibrium concentration that is the adsorptionphase reached equilibrium The adsorption isotherms could be fitted well by the Langmuir model The 119877

119871value in the present

investigation was less than one indicating that the adsorption of the metal ion onto ATS is favorable After treatment with ATS thelevels of heavy metals were observed to decrease by 88 (Ni) 829 (Cd) 815 (Cu) 745 (Cr) and 689 (Pb) Results indicatethat the freely abundant locally available low-cost adsorbent Teff straw can be treated as economically viable for the removal ofmetal ions from textile effluents

1 Introduction

Demands of clothing and apparel increasewith the improvingsense of fashion and lifestyle thus textiles are manufacturedto meet the growing demands In developing countriessuch as Ethiopia textile production becomes their sourceof income that contributes to their gross domestic product(GDP) However this has brought both consequences to suchcountries either in a positive way which is an improvementof economy or in a negative way which led to an increasedanthropogenic impact on the biosphere

Heavy metals particularly Pb Cr Cd and Cu arewidely used for the production of color pigments of textiledyes These heavy metals which have transferred to theenvironment are highly toxic and can bioaccumulate inthe human body aquatic life and natural water bodies andalso possibly get trapped in the soil [1] These toxic heavymetals entering in the aquatic environment are adsorbed ontoparticulatematter although they can form freemetal ions and

soluble complexes that are available for uptake by biologicalorganisms [2]

Various methods of treating effluents containing heavymetals have been developed over years such as chemical pre-cipitation chemical oxidation or reduction electrochemicaltreatment ion exchange reverse osmosis filtration evapo-ration recovery and electrocoagulation [3ndash11] These meth-ods have significant disadvantages including high energyrequirements inefficient metal removal generation of toxicsludge and expensive equipmentTherefore there is a need todevelop an efficient rapid cost-effectively and environmentfriendly method for the removal of heavy metals fromeffluents Adsorption of heavy metals is a new technologyfor treatment of textile effluents containing different typesof heavy metals Adsorption is the adhesion of a chemicalsubstance (adsorbate) onto the surface of a solid (adsorbent)The most widely used adsorbent is activated carbon [12]The adsorption process is being widely used by variousresearchers for the removal of heavy metals [13ndash18] from

2 Journal of Thermodynamics

(a) (b)

Figure 1 Teff straw before treatment (a) and after treatment (b)

waste streams and activated carbon has been frequently usedas an adsorbent

Adsorption isotherm is an empirical relationship usedto predict how much solute can be adsorbed by activatedcarbon [19] Adsorption isotherm is defined as a graphicalrepresentation showing the relationship between the amountadsorbed by a unit weight of adsorbent (eg activatedcarbon) and the amount of adsorbate remaining in a testmedium at equilibrium and it shows the distribution ofadsorbable solute between the liquid and solid phases atvarious equilibrium concentrations [20] The three well-known isotherms are (a) Freundlich (b) Langmuir and (c)BET adsorption isotherm [19]

In this study a new environment friendly cost-effectiveand locally available agrowaste Eragrostis tef adsorbent wasinvestigated for the adsorption of heavy metals (Cr Cd PbNi and Cu) from textile effluents The effects of differentparameters such as the pH the initial metal concentrationthe dose of the adsorption the contact time and temperaturewere studied

2 Materials and Methods

21 Description of the StudyArea Thestudywas carried at theMAA Garment and Textile Factory built near Alula Abanegaairport due southeast of Mekelle city Tigray NorthernEthiopia The study area lies between latitudes 13∘2810158405610158401015840Nlongitudes 39∘3110158405910158401015840EThe factory is owned by Kebire Enter-prises Plc and is fully equipped with state-of-art productionfacilities acquired from the most reputable manufacturersof the world with over 825 sewing machines The industrialarea is spread over 210000m2 of land and it utilizes about24000m3day fresh water The effluent discharge amountsto about 13050m3day that is 544 of the total industrialeffluents

22 Adsorbent Teff straw was used as biomass sample in thisstudy for adsorption of heavy metals from textile effluentsTeff (Eragrostis tef ) is obviously one of Ethiopiarsquos mostimportant cereal crops It is indigenous to the country andit is a fundamental part of the culture tradition and foodRecently the taxonomyof Teffhas been clarified by numericaltaxonomy techniques cytology and biochemistry including

leaf flavonoids and seed protein electrophoretic patterns [21ndash23] The Teff straw was provided by Mekelle UniversityCollege of Agriculture and treated in the Physical Chemistrylaboratory Figure 1 shows some samples of Teff straw beforetreatment and after treatment

23 Sorbent Preparation Teff straw was washed several timeswith double-distilled water to remove all dirt in its originalparticle size followed by filtration and was dried at 100∘CThe cleaned and dried Teff straw was oven-dried at 400∘Cfor three hours to form carbonized Teff straw (CTS) TheCTS was treated with 1M sulfuric acid at room temperatureAcidified Teff Straw was dried overnight at 70∘C and thedried Teff strawwas heated to 120∘CThe reacted product waswashed repeatedly with distilled water Finally the cleanedTeff straw was oven-dried overnight at 100∘C and packed forutilization

24 Sorption Studies

241 Batch Experiments and Adsorption Isotherms Sorp-tion studies were conducted by the batch technique andcolumn test using wastewater from MAA Garment Batchexperiments were carried out to determine the adsorptionisotherms of metal ions onto the adsorbents in 250mL glassflask The flasks were shaken at a constant rate allowingsufficient time for adsorption equilibrium It was assumedthat the applied shaking speed allows all the surface area tocome in contact with heavy metal ions over the course of theexperiments The study was performed at room temperatureto be representative of environmentally relevant conditionAll experiments were carried out in duplicate and the averagevalue was used for further calculationThe pH of the solutionwas measured with a HACH-pH meter The flasks wereplugged and kept closed to avoid the fluctuation of pH dueto the exchange of gases during the experiment The effectsof various parameters on the rate of adsorption process wereobserved by varying contact time adsorbent concentrationtemperature and pHof the solutionThe solution volume (119881)was kept constant The amount of metal adsorbed per unitmass is calculated as

119876119890=(119862119894minus 119862119890) 119881

119898 (1)

Journal of Thermodynamics 3

Table 1 Mean concentration (mgL) with St dev of HMs in MAA Garment and Textile Factory effluents

Sample Parameters Ni Cu Cd Cr PbUntreated Mean plusmn St dev 353 plusmn 033 254 plusmn 074 123 plusmn 022 098 plusmn 007 012 plusmn 002

Treated Mean plusmn St dev 043 plusmn 019 047 plusmn 012 002 plusmn 001 025 plusmn 005 004 plusmn 001

Percentage removed 88 815 829 745 689

where119862119894and119862

119890are the initial and equilibrium concentration

(mgL)119898 is themass of the adsorbent (g) and119881 is the volumeof the solution (mL) Percent metal ion removal (MR) wascalculated using the equation

MR =(119862119894minus 119862119890)

119862119894

lowast 100 (2)

242 ColumnTest Theadsorption experiments were carriedout in columns that were equipped with a stopper forcontrolling the column flow rate This experiment is usefulin understanding and predicting the behavior of the processThe sample solution was passed through the adsorptioncolumn with a known amount of ATS at a flow rate of6mLmin by gravity The flow rate was kept constant bycontrolling the stopper valve

The concentration of residual individual heavy metal inthe sorption medium was determined using fully automatedPC-controlled true double-beam AAS with fast sequentialoperation (Varian AA50 FS Australia) for fast multielementflame AA determinations with features 4 lamp positions andautomatic lamp selection Statistical analysis was performedusing the statistical software packages Detection limits foreach metal on the instrument are Cr 0006mgKg Cd0002mgKg Pb 0010mgKg Ni 0010mgKg and Cu0003mgKg

3 Results and Discussion

31 Adsorption of the Tested Heavy Metals onto ATS Con-centrations of heavy metals of the factoryrsquos effluent arepresented in Table 1 Nickel concentration in the wastewatersample constituted the major portion of the total metal ionsdetermined (353) followed by Cu (254) and Cd (123) whileCr (098) and Pb (012) concentrations were the lowest Theconcentration of nickel in untreated effluent was found tobe 353 plusmn 033 and in treated sample was 043 plusmn 019 it was88 less as compared to untreated effluent (Table 1) Thelevel of copper was 254 plusmn 074 in untreated samples and047 plusmn 012 in treated samples which means 815 less intreated sample And the concentrations of cadmium beforeand after treatment were found to be 123 plusmn 022 and 002 plusmn001 respectively while the levels of the concentration of Pb012 plusmn 002 and 004 plusmn 001 The obtained results revealedthat ATS has good adsorption capacity and is effective for theremoval of heavy metals from textile effluent

32 Effect of Adsorbent Dose on Adsorption The effect ofadsorbent dose on the adsorption of the heavy metals ontoATS was investigated The concentration of heavy metals in

0

20

40

60

80

100

0 50 100 150Time (min)

NiCdCu

CrPb

Met

al re

mov

ed (

)

Figure 2 Effect of contact time on adsorption efficiency

the textile effluent was reduced by 88 (Ni) 829 (Cd)815 (Cu) 745 (Cr) and 689 (Pb) after treatmentMetals adsorption efficiency was increased with increasein adsorbent dose This revealed that the adsorption sitesremain unsaturated during the adsorption reaction whereasthe number of sites available for adsorption site increases byincreasing the adsorbent dose

33 Effect of Contact Time on Adsorption The effect ofcontact time on the adsorption of metal was investigatedFigure 2 shows the percent metal ion removal with respectto time Contact time is one of the most effective factors inbatch adsorption process Adsorption rate initially increasedrapidly and the optimal removal efficiency was reachedwithin about 60min Further increase in contact time did notshow significant change in equilibrium concentration that isthe adsorption phase reached equilibrium

34 Effect of Temperature on Adsorption Effect of tempera-ture on adsorption of the heavy metals onto ATS was studiedby conducting different sets of experiments at differenttemperatures that is 298 308 318 328 and 343∘K It wasobserved that adsorption of metal ions increases with theincrease in the temperature

35 Effect of pH on Adsorption The pH of a solution is animportant parameter in the adsorption process During thisstudy results revealed that the removal of metal ions wasstrongly dependent on the pH of the solution The effect ofpH on adsorption of metal ions onto ATS was studied at


0

05

1

15

2

25

3

35

4

0 2 4 6 8 10 12

NiCdCu

CrPb

Ceqe

Ce (mgL)

Figure 3 Langmuir isotherm showing the variation of adsorption(119862119890119902119890) against the equilibrium concentration (119862

119890) for adsorption of

metal ions onto ATS

Table 2 Isotherm parameters for adsorption of metal ions ontoATS

Isotherm model Metal ion Estimated isotherm parameters119902max (mgg) 119887 (Lmg) 119877

2

Langmuir

Ni 412 0189 0998Cu 34 0173 0982Cd 272 1908 0940Cr 213 0143 0962Pb 175 0114 0945

Metal ion 119899 119870119891 119877

2

Freundlich

Ni 110 124 0748Cd 211 352 0977Cu 153 201 0967Cr 150 177 0939Pb 151 182 0957

pH 10ndash110 and the maximum removal capacity of ATS wasfound to be at pH 65 Percent metal ions removal increasedrapidly with the increase in pH of the solution initially andthe optimal pH was observed at pH 65 Further increase inpH causes a drastic decrease in the adsorption percentageThis might be due to the weakening of electrostatic forceof attraction between the oppositely charged adsorbate andadsorbent which ultimately leads to the reduction in sorptioncapacity [24]

36 Adsorption Isotherm Adsorption is usually describedthrough isotherms that is functions which connect theamount of adsorbate on the adsorbent Distribution of metalions between the liquid phase and the solid phase can bedescribed by several isotherm models such as Langmuirand Freundlich The Langmuir isotherm assumes monolayeradsorption onto a surface containing a finite number ofadsorption sites of uniform strategies with no transmigration

0

05

1

15

2

25

3

35

4

0 2 4 6 8 10 12

PbCrCu

CdNi

ln q e

ln Ce

Figure 4 Freundlich isotherm representing variation of ln(119902119890)with

respect to ln(119862119890) for adsorption of metal ions onto ATS

of adsorbate in the plane surface [25] Once a site is filled nofurther sorption can take place at that site This indicates thatthe surface reaches a saturation point where the maximumadsorption of the surface will be achieved The isotherm isrepresented by

119862119890

119902119890

=1

119887119902max+119862119890

119902max (3)

The linear plot of specific adsorption (119862119890119902119890) against the

equilibrium concentration (119862119890) (Figure 3) shows that the

adsorption obeys the Langmuir model The constants 119887and 119902max relate to the energy of adsorption and maximumadsorption capacity and their values are obtained from theslope and interception of the plot and are presented inTable 2

The Freundlich isotherm is introduced as an empiricalmodel where 119902

119890represents the amount adsorbed per amount

of adsorbent at the equilibrium (mgg) 119862119890represents the

equilibrium concentration (mgL) and 119870119891and 119899 are param-

eters that depend on the adsorbate and adsorbentConsider

119902119890= 1198701198911198621119899

119890 (4)

The equation can be linearized and the temperature depen-dent constants119870

119891and 1119899 found by linear regression

ln 119902119890= ln119870

119891minus1

119899ln119862119890 (5)

where 119870119891and 119899 are Freundlich constants which correspond

to adsorption capacity and adsorption intensity respectivelyFreundlich equilibrium constants were determined from theplot of ln 119902

119890versus ln119862

119890from Figure 4 on the basis of the

linear form of Freundlich equation The 119899 value indicates thedegree of nonlinearity between solution concentration andadsorption as follows if 119899 = 1 then adsorption is linear if119899 lt 1 then adsorption is a chemical process if 119899 gt 1 thenadsorption is a physical process The 119899 value in Freundlich


equation was found to be 110ndash211 (Table 2) The situation119899 gt 1 is most common and may be due to a distribution ofsurface sites or any factor that causes a decrease in adsorbent-adsorbate interaction with increasing surface density [26]and the values of 119899 within the range of 1ndash10 represent goodadsorption [27 28] In the present study since 119899 lies between1 and 10 it indicates the physical adsorption ofmetal ions ontoATS

In both cases linear plots were obtained which reveal theapplicability of these isotherms on the ongoing adsorptionprocess Figures 3 and 4 exhibit Langmuir and Freundlichplots respectively for the adsorption of metal ions onto ATSand different Langmuir and Freundlich constants derivedfrom these plots are presented in Table 2 Nearly similarresults have been reported in the literature [29ndash31] forLangmuir and Freundlich models

Langmuir and Freundlich adsorption constants and cor-relation coefficients (1198772) are presented in Table 2 To find themost appropriate model for the metal ions adsorption datawere fitted to Langmuir and Freundlich isotherm modelsResults revealed that Langmuir adsorption isotherm was thebest model for the metal ions adsorption onto ATS with1198772 of 0998 The essential features of Langmuir adsorption

isotherm parameter can be used to predict the affinitybetween the sorbate and sorbent using a dimensionlessconstant called separation factor or equilibrium parameter(119877119871) which is expressed by the following relationship [32 33]

119877119871=1

(1 + 119887119862119894) (6)

where 119887 is the Langmuir constant and 119862119894is the initial

concentrationThevalue of119877119871indicated the type of Langmuir

isotherm to be irreversible (119877119871= 0) linear (119877

119871= 1)

unfavorable (119877119871gt 1) or favorable (0 lt 119877

119871lt 1) [34] The

119877119871values between 0 and 1 indicate favorable adsorption The119877119871value in the present investigation was found to be 0298ndash

0986 indicating that the adsorption of the metal ion ontoATS is favorable

4 Conclusions

Teff (Eragrostis tef) straw is environment friendly cost-effective and locally available agrowaste adsorbent for theadsorption of metal ions from textile effluents Results fromthis study showed that adsorption of heavy metals ontoATS increases with the amount of adsorbent This may beexplained because of the fact that adsorption is a surfacephenomenon where adsorbate molecules occupy specificsites on the adsorbent These sites are commonly known asactive centers The concentration of these active centers onthe surface is further related to the pore size and pore volumeavailable after impregnation This explains why increasingthe quantity of adsorbent results in increased adsorptionResults revealed that initially the removal increase rapidlyhowever after some times the rate becomes almost constantThis is because all the available active centers on the adsorbenthave been occupied and there are no further sites andhence no further adsorption is possible The time when this

phenomenon occurs therefore may be termed optimumtime

The adsorption isotherms could well be fitted by theLangmuir model The 119877

119871value in the present investigation

was less than one indicating that the adsorption of the metalion ontoATS is favorable In treatment withATS the removalof metal ions from textile wastewater sample is high wherebythe percentage of removal is more than 80 percent of theinitial concentration Since Teff Straw is freely abundantlocally available low-cost adsorbent and has a considerablehigh adsorption capacity it may be treated as economicallyviable for removal of metal ions from textile effluents

Acknowledgments

This studywas done in theDepartment of ChemistryMekelleUniversity Ethiopia The author is grateful to Dr AbrahaGKidan for providing column adsorption apparatus Theauthor would like to thankMrMehari (the factorymanager)Mr Amanuel (textile engineer) and Mr Mesfin (treatmentplant supervisor) for providing the necessary facilities tocarry out this work

References

[1] N Mathur P Bhatnagar and P Bakre ldquoAssessing mutagenicityof textile dyes from pali (Rajasthan) using ames bioassayrdquoApplied Ecology and Environmental Research vol 4 no 1 pp111ndash118 2006

[2] P U Singare R S Lokhande and K U Naik ldquoA case study ofsome lakes located at and around thane city of MaharashtraIndia with special reference to physico-chemical properties andheavy metal content of lake waterrdquo Interdisciplinary Environ-mental Review vol 11 no 1 pp 90ndash107 2010

[3] J O Esalah M E Weber and J H Vera ldquoRemoval of leadcadmium and zinc from aqueous solutions by precipitationwith sodium di-(n-octyl) phosphinaterdquo Canadian Journal ofChemical Engineering vol 78 no 5 pp 948ndash954 2000

[4] A I Zouboulis K A Matis B G Lanara and C L NeskovicldquoRemoval of cadmium from dilute solutions by hydroxy apatiteII floatation studiesrdquo Separation Science and Technology vol 32no 10 pp 1755ndash1767 1997

[5] A I Zouboulis K A Matis B G Lanara and C L NeskovicldquoRemoval of cadmium from dilute solutions by hydroxy apatiteII floatation studiesrdquo in The Protocols K R Fall and W RStevens Eds vol 1 of TCPIP Illustrated Addison-WesleyReading Mass USA 2nd edition 2011

[6] L Canet M Ilpide and P Seta ldquoEfficient facilitated transportof lead cadmium zinc and silver across a flat-sheet-supportedliquid membrane mediated by lasalocid Ardquo Separation Scienceand Technology vol 37 no 8 pp 1851ndash1860 2002

[7] K Dermentiz A Christoforidis E Valsamidou A Loucas andKGreece ldquoRemoval of nickel copper zinc and chromium fromsynthetic and industrial wastewater by electrocoagulationrdquoInternational Journal of Environmental Sciences vol 1 no 5 pp697ndash710 2011

[8] V J Inglezakis M D Loizidou and H P Grigoropoulou ldquoIonexchange of Pb2+ Cu2+ Fe3+ and Cr3+ on natural clinoptiloliteselectivity determination and influence of acidity on metaluptakerdquo Journal of Colloid and Interface Science vol 261 no 1pp 49ndash54 2003


[9] P T Bolger and D C Szlag ldquoElectrochemical treatment andreuse of nickel plating rinsewatersrdquoEnvironmental Progress vol21 no 3 pp 203ndash208 2002

[10] K Dermentzis ldquoRemoval of nickel from electroplating rinsewaters using electrostatic shielding electrodialysiselectrode-ionizationrdquo Journal of HazardousMaterials vol 173 no 1ndash3 pp647ndash652 2010

[11] M A Amer F I Khaili and A M Awwad ldquoAdsorption of leadzinc and cadmium ions on polyphosphate-modified kaoliniteclayrdquo Journal of Environmental Chemistry andEcotoxicology vol2 no 1 pp 1ndash8 2010

[12] N O Reuben and J A Miebaka ldquoChromium (VI) adsorptionrate in the treatment of liquid phase oil based drill cuttingsrdquoAfrican Journal of Environmental Science and Technology vol 2no 4 pp 68ndash674 2008

[13] R Ahmed T Yamin M S Ansari and S M Hasany ldquoSorptionbehaviour of lead(II) ions from aqueous solution onto Haroriver sandrdquo Adsorption Science and Technology vol 24 no 6pp 475ndash486 2006

[14] D F Aloko and E A Afolabi ldquoTitanium dioxide as a cathodematerial in a dry cellrdquo Leonardo Electronics Journal of Practicesand Technologies vol 11 pp 97ndash108 2007

[15] D F Aloko and E A Afolabi ldquoModel development of theadsorption of cations on manganese dioxide (MnO

2) used in

a Leclanche dry cellrdquo Leonardo Journal of Sciences vol 8 pp13ndash20 2006

[16] C C Chen and Y C Chung ldquoArsenic removal using a biopoly-mer chitosan sorbentrdquo Journal of Environmental Science andHealth - Part A ToxicHazardous Substances and EnvironmentalEngineering vol 41 no 4 pp 645ndash658 2006

[17] N Amin S Kaneco T Kitagawa et al ldquoRemoval of arsenicin aqueous solutions by adsorption onto waste rice huskrdquoIndustrial and Engineering Chemistry Research vol 45 no 24pp 8105ndash8110 2006

[18] A M M Khaled A Comparative study for distribution of someheavy metals in aquatic organisms fished from Alexandria region[PhD thesis] Chemistry Department Faculty of ScienceAlexandria University Alexandria Egypt 1998

[19] K Steve T Erika T Reynold andM Paul ldquoActivated carbon aunit operations and processes of activated carbonrdquo in Environ-mental Engineering vol 25 pp 350ndash749 PWS Publishing 2ndedition 1998

[20] C Ng J N Losso W E Marshall and R M Rao ldquoFreundlichadsorption isotherms of agricultural by-product-based pow-dered activated carbons in a geosmin-water systemrdquoBioresourceTechnology vol 85 no 2 pp 131ndash135 2002

[21] B M G Jones J Ponti A Tavassoli and P A Dixon ldquoRelation-ships of the ethiopian cereal trsquoef (Eragrostis tef (Zucc) Trotter)evidence from morphology and chromosome numberrdquo Annalsof Botany vol 42 no 6 pp 1369ndash1373 1978

[22] S H Costanza J M J Dewet and J R Harlan ldquoLiteraturereview and numerical taxonomy of Eragrostis tef (Trsquoef)rdquo Eco-nomic Botany vol 33 no 4 pp 413ndash424 1979

[23] E Bekele and R N Lester ldquoBiochemical assessment of therelationships of Eragrostis tef (Zucc) trotter with some wildEragrostis species (Gramineae)rdquo Annals of Botany vol 48 no5 pp 717ndash725 1981

[24] S S Baral S N Das and P Rath ldquoHexavalent chromiumremoval from aqueous solution by adsorption on treated saw-dustrdquo Biochemical Engineering Journal vol 31 no 3 pp 216ndash222 2006

[25] B H Hameed A T M Din and A L Ahmad ldquoAdsorption ofmethylene blue onto bamboo-based activated carbon kineticsand equilibrium studiesrdquo Journal of Hazardous Materials vol141 no 3 pp 819ndash825 2007

[26] B E Reed and M R Matsumoto ldquoModeling cadmium adsorp-tion by activated carbon using the Langmuir and Freundlichisotherm expressionsrdquo Separation Science and Technology vol28 no 13-14 pp 2179ndash2195 1993

[27] G McKay M S Otterburn and A G Sweeney ldquoThe removalof colour from effluent using various adsorbents III Silica rateprocessesrdquoWater Research vol 14 no 1 pp 15ndash20 1980

[28] A Ozer and H B Pirincci ldquoThe adsorption of Cd(II) ionson sulphuric acid-treated wheat branrdquo Journal of HazardousMaterials vol 137 no 2 pp 849ndash855 2006

[29] A Mittal L Kurup and J Mittal ldquoFreundlich and Langmuiradsorption isotherms and kinetics for the removal of Tartrazinefrom aqueous solutions using hen feathersrdquo Journal of Haz-ardous Materials vol 146 no 1-2 pp 243ndash248 2007

[30] M Malakootian J Nouri and H Hossaini ldquoRemoval of heavymetals from paint industryrsquos wastewater using Leca as anavailable adsorbentrdquo International Journal of EnvironmentalScience and Technology vol 6 no 2 pp 183ndash190 2009

[31] H Liu Y Dong H Wang and Y Liu ldquoAdsorption behaviorof ammonium by a bioadsorbentmdashBoston ivy leaf powderrdquoJournal of Environmental Sciences vol 22 no 10 pp 1513ndash15182010

[32] K R Hall L C Eagleton A Acrivos and T VermeulenldquoPore- and solid-diffusion kinetics in fixed-bed adsorptionunder constant-pattern conditionsrdquo Industrial and EngineeringChemistry Fundamentals vol 5 no 2 pp 212ndash223 1966

[33] P K Malik ldquoDye removal from wastewater using activatedcarbon developed from sawdust adsorption equilibrium andkineticsrdquo Journal of Hazardous Materials vol 113 no 1ndash3 pp81ndash88 2004

[34] G McKay H S Blair and J R Gardner ldquoAdsorption of dyeson chitinrdquo Journal of Applied Polymer Science vol 27 no 8 pp3043ndash3057 1982

Submit your manuscripts athttpwwwhindawicom

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AerodynamicsJournal of

Volume 2014


PhotonicsJournal of


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Biophysics


ThermodynamicsJournal of


(a) (b)

Figure 1 Teff straw before treatment (a) and after treatment (b)

waste streams and activated carbon has been frequently usedas an adsorbent

Adsorption isotherm is an empirical relationship usedto predict how much solute can be adsorbed by activatedcarbon [19] Adsorption isotherm is defined as a graphicalrepresentation showing the relationship between the amountadsorbed by a unit weight of adsorbent (eg activatedcarbon) and the amount of adsorbate remaining in a testmedium at equilibrium and it shows the distribution ofadsorbable solute between the liquid and solid phases atvarious equilibrium concentrations [20] The three well-known isotherms are (a) Freundlich (b) Langmuir and (c)BET adsorption isotherm [19]

In this study a new environment friendly cost-effectiveand locally available agrowaste Eragrostis tef adsorbent wasinvestigated for the adsorption of heavy metals (Cr Cd PbNi and Cu) from textile effluents The effects of differentparameters such as the pH the initial metal concentrationthe dose of the adsorption the contact time and temperaturewere studied

2 Materials and Methods

21 Description of the StudyArea Thestudywas carried at theMAA Garment and Textile Factory built near Alula Abanegaairport due southeast of Mekelle city Tigray NorthernEthiopia The study area lies between latitudes 13∘2810158405610158401015840Nlongitudes 39∘3110158405910158401015840EThe factory is owned by Kebire Enter-prises Plc and is fully equipped with state-of-art productionfacilities acquired from the most reputable manufacturersof the world with over 825 sewing machines The industrialarea is spread over 210000m2 of land and it utilizes about24000m3day fresh water The effluent discharge amountsto about 13050m3day that is 544 of the total industrialeffluents

22 Adsorbent Teff straw was used as biomass sample in thisstudy for adsorption of heavy metals from textile effluentsTeff (Eragrostis tef ) is obviously one of Ethiopiarsquos mostimportant cereal crops It is indigenous to the country andit is a fundamental part of the culture tradition and foodRecently the taxonomyof Teffhas been clarified by numericaltaxonomy techniques cytology and biochemistry including

leaf flavonoids and seed protein electrophoretic patterns [21ndash23] The Teff straw was provided by Mekelle UniversityCollege of Agriculture and treated in the Physical Chemistrylaboratory Figure 1 shows some samples of Teff straw beforetreatment and after treatment

23 Sorbent Preparation Teff straw was washed several timeswith double-distilled water to remove all dirt in its originalparticle size followed by filtration and was dried at 100∘CThe cleaned and dried Teff straw was oven-dried at 400∘Cfor three hours to form carbonized Teff straw (CTS) TheCTS was treated with 1M sulfuric acid at room temperatureAcidified Teff Straw was dried overnight at 70∘C and thedried Teff strawwas heated to 120∘CThe reacted product waswashed repeatedly with distilled water Finally the cleanedTeff straw was oven-dried overnight at 100∘C and packed forutilization

24 Sorption Studies

241 Batch Experiments and Adsorption Isotherms Sorp-tion studies were conducted by the batch technique andcolumn test using wastewater from MAA Garment Batchexperiments were carried out to determine the adsorptionisotherms of metal ions onto the adsorbents in 250mL glassflask The flasks were shaken at a constant rate allowingsufficient time for adsorption equilibrium It was assumedthat the applied shaking speed allows all the surface area tocome in contact with heavy metal ions over the course of theexperiments The study was performed at room temperatureto be representative of environmentally relevant conditionAll experiments were carried out in duplicate and the averagevalue was used for further calculationThe pH of the solutionwas measured with a HACH-pH meter The flasks wereplugged and kept closed to avoid the fluctuation of pH dueto the exchange of gases during the experiment The effectsof various parameters on the rate of adsorption process wereobserved by varying contact time adsorbent concentrationtemperature and pHof the solutionThe solution volume (119881)was kept constant The amount of metal adsorbed per unitmass is calculated as

119876119890=(119862119894minus 119862119890) 119881

119898 (1)






where119862119894and119862



MR =(119862119894minus 119862119890)

119862119894

lowast 100 (2)






0

20

40

60

80

100

0 50 100 150Time (min)

NiCdCu

CrPb

Met

al re

mov

ed (

)







0

05

1

15

2

25

3

35

4

0 2 4 6 8 10 12

NiCdCu

CrPb

Ceqe

Ce (mgL)



metal ions onto ATS



2

Langmuir

Ni 412 0189 0998Cu 34 0173 0982Cd 272 1908 0940Cr 213 0143 0962Pb 175 0114 0945

Metal ion 119899 119870119891 119877

2

Freundlich

Ni 110 124 0748Cd 211 352 0977Cu 153 201 0967Cr 150 177 0939Pb 151 182 0957



0

05

1

15

2

25

3

35

4

0 2 4 6 8 10 12

PbCrCu

CdNi

ln q e

ln Ce




119862119890

119902119890

=1

119887119902max+119862119890

119902max (3)









119902119890= 1198701198911198621119899

119890 (4)



ln 119902119890= ln119870

119891minus1

119899ln119862119890 (5)



119890versus ln119862








119877119871=1

(1 + 119887119862119894) (6)




119871= 1)


119871lt 1) [34] The



4 Conclusions






Acknowledgments


References

















2) used in


























FluidsJournal of


Journal of










Superconductivity




GravityJournal of








Journal of






Volume 2014


PhotonicsJournal of


Journal of

Biophysics








where119862119894and119862



MR =(119862119894minus 119862119890)

119862119894

lowast 100 (2)






0

20

40

60

80

100

0 50 100 150Time (min)

NiCdCu

CrPb

Met

al re

mov

ed (

)







0

05

1

15

2

25

3

35

4

0 2 4 6 8 10 12

NiCdCu

CrPb

Ceqe

Ce (mgL)



metal ions onto ATS



2

Langmuir

Ni 412 0189 0998Cu 34 0173 0982Cd 272 1908 0940Cr 213 0143 0962Pb 175 0114 0945

Metal ion 119899 119870119891 119877

2

Freundlich

Ni 110 124 0748Cd 211 352 0977Cu 153 201 0967Cr 150 177 0939Pb 151 182 0957



0

05

1

15

2

25

3

35

4

0 2 4 6 8 10 12

PbCrCu

CdNi

ln q e

ln Ce




119862119890

119902119890

=1

119887119902max+119862119890

119902max (3)









119902119890= 1198701198911198621119899

119890 (4)



ln 119902119890= ln119870

119891minus1

119899ln119862119890 (5)



119890versus ln119862








119877119871=1

(1 + 119887119862119894) (6)




119871= 1)


119871lt 1) [34] The



4 Conclusions






Acknowledgments


References

















2) used in


























FluidsJournal of


Journal of










Superconductivity




GravityJournal of








Journal of






Volume 2014


PhotonicsJournal of


Journal of

Biophysics




0

05

1

15

2

25

3

35

4

0 2 4 6 8 10 12

NiCdCu

CrPb

Ceqe

Ce (mgL)



metal ions onto ATS



2

Langmuir

Ni 412 0189 0998Cu 34 0173 0982Cd 272 1908 0940Cr 213 0143 0962Pb 175 0114 0945

Metal ion 119899 119870119891 119877

2

Freundlich

Ni 110 124 0748Cd 211 352 0977Cu 153 201 0967Cr 150 177 0939Pb 151 182 0957



0

05

1

15

2

25

3

35

4

0 2 4 6 8 10 12

PbCrCu

CdNi

ln q e

ln Ce




119862119890

119902119890

=1

119887119902max+119862119890

119902max (3)









119902119890= 1198701198911198621119899

119890 (4)



ln 119902119890= ln119870

119891minus1

119899ln119862119890 (5)



119890versus ln119862








119877119871=1

(1 + 119887119862119894) (6)




119871= 1)


119871lt 1) [34] The



4 Conclusions






Acknowledgments


References

















2) used in


























FluidsJournal of


Journal of










Superconductivity




GravityJournal of








Journal of






Volume 2014


PhotonicsJournal of


Journal of

Biophysics








119877119871=1

(1 + 119887119862119894) (6)




119871= 1)


119871lt 1) [34] The



4 Conclusions






Acknowledgments


References

















2) used in


























FluidsJournal of


Journal of










Superconductivity




GravityJournal of








Journal of






Volume 2014


PhotonicsJournal of


Journal of

Biophysics











2) used in


























FluidsJournal of


Journal of










Superconductivity




GravityJournal of








Journal of






Volume 2014


PhotonicsJournal of


Journal of

Biophysics








FluidsJournal of


Journal of










Superconductivity




GravityJournal of








Journal of






Volume 2014


PhotonicsJournal of


Journal of

Biophysics



Documents

Research Article Batch Sorption Experiments: Langmuir and ...downloads.hindawi.com/archive/2013/375830.pdf · Batch Experiments and Adsorption Isotherms. Sorp-tion studies were conducted