research article bioremediation of waste water containing...

Research ArticleBioremediation of Waste Water ContainingHazardous Cadmium Ion with Ion ImprintedInterpenetrating Polymer Networks

Girija Parameswaran1 and Beena Mathew2

1 Department of Chemistry S D College Alappuzha Kerala 690104 India2 Schoolof Chemical Sciences Mahatma Gandhi University Kottayam Kerala 686560 India

Correspondence should be addressed to Girija Parameswaran girijakallelilgmailcom

Received 31 December 2013 Accepted 15 February 2014 Published 16 April 2014

Academic Editor Jesus Simal-Gandara

Copyright copy 2014 G Parameswaran and B Mathew This is an open access article distributed under the Creative CommonsAttribution License which permits unrestricted use distribution and reproduction in any medium provided the original work isproperly cited

A novel Cd(II) ion imprinted interpenetrating polymer network (Cd(II)IIP) was prepared by free radical polymerization usingalginic acid and NNMBA-crosslinked polyacrylamide in presence of initiator potassium persulphate Cd(II)IIP showed highercapacity and selectivity than the nonimprinted polymer (NIP) The sorption capacities of Cd(II)IIP and NIP for Cd(II) ions were0886 and 0663 meqmoleminus1 respectively Kinetics studies showed that the sorption process closely agreed with a pseudosecond-order model The thermodynamic data suggest that the sorption is a spontaneous endothermic process Equilibrium experimentsshowed very goodfitwith the Langmuir isotherm equation for themonolayer sorption process Cd(II)IIP exhibited good reusabilityand the sorption capacity of Cd(II)IIP was stable within the first 4 cycles without obvious decrease Also Cd(II)IIP showed almost100 removal efficiency for Cd(II) ions in real environmental water samples indicating that Cd(II)IIP could have wide applicationprospects in Cd(II) ion removal

1 Introduction

Water pollution is one of the most serious environmentalproblems of the present day Water obtained from differentsources is associated with a large number of impuritiesAmong them heavymetal toxicity is very crucial Occurrenceof toxicmetals in lakes ponds ditch and riverwater affect thelives of local people that depend on these water sources fortheir daily requirements [1] Currently anthropogenic inputsof metals exceed natural input High levels of Cd Cu Pband Fe can act as ecological toxins in aquatic and terres-trial ecosystem [2 3] Cadmium as a hazardous pollutantcommonly present in the living environment represents animportant risk to human health Cadmium and its com-pounds are highly toxic and exposure to this metal is knownto cause cancer and targets the bodyrsquos cardiovascular renalgastrointestinal neurological reproductive and respiratorysystemsThe approach of bioremediation is an innovative toolwith greater potential to remove heavy metal ions in water

bodies The method of ion imprinting has become one of thefast-growing technologies that have achieved a lot of attentionrecently especially in the area of materials science The IIPsare synthesized on the principle of enzyme phenomenonwhereby a monomer is altered by a polymerization thattakes place in the presence of a template that will be laterremoved to create cavities that will recognize only the analyteof interest Also the international agency for research oncancer has classified cadmium as a human carcinogen [4]Zhai et al have reported selective solid-phase extractionof trace cadmium(II) ions with an ion imprinted polymer(IIP) prepared by a dual ligand monomer [5] An imprintedorganicinorganic hybrid sorbent for selective separation ofcadmium from aqueous solution has been proposed by Luand Yan [6] Cd(II) ion imprinted polymer containing epoxyresin has been synthesized and characterized by Pan andcoworkers [7] The designing and synthesis of cadmium (II)ion imprinted polymer are particularly important becausecadmium is among the 13 toxic metal species on the priority

Hindawi Publishing CorporationAdvances in Environmental ChemistryVolume 2014 Article ID 394841 10 pageshttpdxdoiorg1011552014394841

2 Advances in Environmental Chemistry

pollutant list of the Environmental Protection Agency (EPA)[8] Alginate is one of the most extensively investigatedbiopolymer for the removal of heavymetal ions from aqueoussolutions [9ndash11]There have been few reports on the synthesisof ion imprinted polymers for removal of Cd(II) from watersamples [12ndash15] Thus the extraction preconcentration anddetermination of trace cadmium from the natural water arevery important and need much more attention

In the present study we aim to fabricate a noveltype of Cd(II) ion imprinted interpenetrating polymer net-work using a natural biosorbent alginic acid which iscrosslinked by the hydrophilic crosslinker NN1015840 methylene-bis-acrylamide and template Cd(II) ion The hydrophilicnature of crosslinker increased the swelling ability of poly-mer network which favours effective cadmium ion bindingThe newly prepared interpenetrating polymer network isadvantageous because it showed high sorption capacity andremarkable selectivity in Cd(II) ion separation from mixtureof metal ions Compared to the previous reports the presentIIP showed high sorption capacity and good reusability forCd(II) ion and the synthesis of IIP involves clean technologyand can be used for waste water treatment The biopolymersare capable of removing metal ions The method of prepara-tion of the IPN can be considered as ldquogreenrdquo and also simplerapid low cost and environment friendly due to the use ofaqueous medium

2 Materials and Methods

Reagents of analytical and spectral grade were used for allexperiments Cadmium acetate used in the present study isof analytical grade (99 pure) and solutions were preparedby dissolving the required quantity of CdCH

3

(COO)2

inmillipore water The monomers used in this study namelyacrylamide (999 pure) and crosslinking agent NNMBAwere obtained from SRL (Mumbai) Alginic acid (985pure) was obtained from Merk (India) Fourier transforminfrared (FT-IR) spectra of the imprinted nonimprintedand the Cd(II) ion bound polymer networks were recordedbetween 4000 and 400 cmminus1 using a Perkin Elmer 400 FT-IR spectrophotometer and far IR spectra of Cd(II) ion boundpolymer networks were recorded between 400 and 100 cmminus1using the same instrument UV-vis spectrophotometric mea-surements were carried out using Shimadzu 2400UV-visspectrophotometer SEM-EDAX were taken on JEOL-JSM-840A scanning electron microscope in nitrogen atmosphereTG curves were recorded on a Shimadzu D-740 thermalanalyser at a heating rate of 10∘C min from 20 to 900∘C innitrogen atmosphere The amount of metal ion sorbed pergram of imprinted and nonimprinted polymers from metalion solutions was determined using Perkin Elmer atomicabsorption analyzer 300

21 Preparation of Cd(II) Ion Imprinted (IIP) and Non-imprinted (NIP) Polymer Networks Alginic acid (75 g)was mixed with (064 g) of cadmium acetate in aqueousmedium This mixture was added to an aqueous solutionof acrylamide (1066 g) and NN-methylenebisacrylamide

(NNMBA) (771 g) and kept at 70∘C in a water bath withstirring using potassium persulphate (100mg) as initiatorThe polymer obtained was washed with water to removeunreacted monomer and with 2N HCl to remove Cd(II) ionThe bulk polymer obtained was dried sieved and weighedNonimprinted polymer networks were also prepared usingthe same procedure without metal ions

22Metal Ion Binding In order to investigate specific rebind-ing capacity Cd(II) ion imprinted and nonimprinted poly-mers (500mg) were equilibrated with Cd(II) Co(II) Cu(II)and Ni(II) (1ndash5 ppm 10mL) ion solution The concentrationof template metal ion solution before and after binding wasdetermined by atomic absorption spectrophotometry (AAS)

23 Swelling Studies 100mg of Cd(II) ion imprinted non-imprinted and corresponding Cd(II) bound polymers wasallowed to swell in 10mL water for 24 h After 24 h thepolymers were filtered and surface water was carefully wipedoff and the final swollen weight was determined From theswollen and the dry weights of the sample the EWC () wascalculated using the following equation

EWC ()

=weight of wet polymer minus weight of dry polymer

weight of dry polymertimes 100

(1)

24 Optimization of the Cd(II) Ion Rebinding Conditions Inorder to optimize the conditions of Cd(II) ion rebindingby imprinted and nonimprinted polymers factors affectingrebinding such as effect of concentration time and pH of theCd(II) ion solution on binding were investigated

25 Effect of Concentration The batch-wise metal ion bind-ing experimentswere carried out using (500mg) of imprintedand nonimprinted polymer to evaluate the effect of concen-tration of template solution on rebinding

From the difference in concentration of template solutionbefore and after incubation the amount of Cd(II) ion boundwas determined Similar rebinding studies at various concen-trations of metal ion (1ndash5 ppm 10mL) were carried out andanalyzed by AAS

26 Effect of Time The time required for maximum bindingwas determined by batch equilibration method 500mg ofimprinted and nonimprinted polymers was equilibrated with(5 ppm 10mL) of Cd(II) ion solution and metal ion boundwas determined at regular intervals of time and analyzed byAAS

27 Effect of pH on Cd(II) Ion Binding About 100mg ofimprinted and nonimprinted polymers was equilibrated withCd(II) ion (5 ppm 10mL) at different pH After the removalof polymer particles the amounts of Cd(II) ion bound at eachpH were determined by AAS

Advances in Environmental Chemistry 3

28 Sorption Studies Aqueous solution of Cd(II) ion (5 ppm10mL)was added to (100mg) of imprinted and nonimprintedpolymers The solutions were shaken in stoppered bottles Atregular time intervals the concentration of Cd(II) ion wasfound out by atomic absorption spectrophotometry Sorptioncapacity was investigated using Langmuirrsquos and Freundlichrsquosisotherms

29 Sorption Kinetics Models Different sets of imprintedpolymer (100mg) were equilibrated with Cd(II) ion solution(5 ppm 10mL) at room temperature using a thermostat Afterremoving the polymer particles the remaining concentrationof Cd(II) ion was determined at equal intervals of timeand analyzed by AAS To describe the adsorption kineticbehavior of Cd(II) ion imprinted polymer network two typesof kinetic models were tested namely the pseudofirst-ordermodel and pseudosecond-order model The binding agreeswith pseudosecond-order equation

210 Effect of Temperature The effect of temperature onthe sorption of Cd(II) ion on imprinted polymer networkwas investigated Imprinted polymer and nonimprinted poly-mer (100mg) were equilibrated with cadmium ion solution(10mL 5 ppm) at temperature varying from 25 to 40∘C TheCd(II) ion bound at each temperature was determined byAAS The thermodynamic parameters such as Δ119866119900 Δ119867119900and Δ119878119900 were calculated by applying the vanrsquot Hoff equationConsider

ln119870119889

= minusΔ119867119900

119877119879+Δ119878119900

119877 (2)

where Δ119866119900 is change in free energy (kJmoleminus1) Δ119867119900 is thechange in enthalpy (kJmoleminus1) Δ119878119900 is the change in entropy(kJmoleminus1Kminus1)119879 is the absolute temperature (K)119877 is the gasconstant and119870

119889

is the equilibrium constant

211 Selectivity Studies Selectivity studies were carried outby column experiment Cd(II) ion imprinted polymer (1 g)was slurred with demineralized water (DMW) and thenpoured into a Pyrex glass column (id40mm) plucked withsmall portion of glass wool at the bottom The column waspreconditioned by passing DMW followed by the mixture ofmetal ion solution (5 ppm 10mL) that was passed throughthe column at a flow rate of sim05mLminminus1 The elutedsolution was collected and the amount of metal ion boundwas determined by atomic absorption spectrophotometricmethod

3 Results and Discussion

31 Synthesis of Cd(II) Ion Imprinted and NonimprintedInterpenetrating PolymerNetworks TheCd(II) ion imprintedpolymer networks were synthesized by free radical poly-merization of acrylamide and NN-methylenebisacrylamide(NNMBA) in presence of alginic acid Potassium persulphate(100mg) was used as initiator and Cd(II) ion was used astemplate and the polymerization was carried out at 70∘C

300 400 500 600 700 80002

04

06

08

10

b

a

Abso

rban

ce

Wavelength (nm)

Figure 1 UV-vis spectra of (a) Cd(II) ion desorbed and (b) Cd(II)ion bound imprinted polymers

(Scheme 1) The bulk polymer obtained was washed withwater to remove unreacted monomers and with dilute HClto remove Cd(II) ions The polymer was dried crushed andsieved Nonimprinted polymer networks were also preparedwithout using the template metal ion

32 Characterization of NNMBA-Crosslinked Cd(II)Ion Imprinted and Nonimprinted InterpenetratingPolymer Networks

321 FT-IR Spectra FT-IR spectrum of the IPN is differentfrom those of the pure polymers because in interpenetratingpolymer networks there will be intermolecular interactionsThe carboxylate group plays an important role in metalsorption property of alginic acid FT-IR spectra of Cd(II)ion imprinted polymer networks showed absorption bands at1643 cmminus1 which is assigned to carboxylate group of alginicacid This band is shifted to 1634 cmminus1 after Cd(II) ionbinding This result showed that Cd(II) ion binding takesplace at carboxylate group of alginate Imprinted polymershowed bands at 2923 cmminus1 and nonimprinted polymershowed bands at 2953 cmminus1 due to CndashH stretching vibrations

322 UV-Vis Spectra UV-vis spectra of Cd(II) ion imprintedinterpenetrating polymer networks and the correspondingCd(II) ion bound polymer networks are shown in Figure 1Cd(II) ion imprinted polymer showed bands at 615 544 and434 nm After Cd(II) ion binding imprinted polymer thesebands are shifted to 663 623 and 540 nm Similar trendsare seen in nonimprinted polymers The shift in wavelengthto higher region indicates structural changes that occurredon molecules As a result of interaction of Cd(II) ion withnonbonding electrons in the carboxylate group of alginicacid a shift in the wavelengthmaxima takes placeThismightbe due to 119899 rarr 120587lowast transitions Ligand to metal chargetransfer bands are obtained at 294 and 327 nm in imprintedand Cd(II) ion bound polymers


NNMBAO O

N NH H

AcrylamideO

NH2

K2S2O8 70∘C

Alginic acid

IIP

M++ M++

M++

OO

O OO

O

OHO HO

OH

OHOHOH

n

m

Scheme 1 Synthesis of Cd(II) ion imprinted interpenetrating polymer networks

0 10 20 30 40 50 60 70

10

20

30

40

50

60

70

80

Cd(II) ion desorbed polymer

Cd(II) bound polymer

Inte

nsity

(au

)

2120579 (deg)

Figure 2 XRD pattern of imprinted and Cd(II) bound polymers

33 X-Ray Diffraction Patterns X-ray diffraction patternsof Cd(II) ion imprinted and bound polymers are shown inFigure 2 The XRD patterns of both polymers exhibited simi-lar patterns which indicate an amorphous nature Generallythe amorphous compounds are denoted by very broad halopeaks XRD patterns of both imprinted and metal ion boundpolymers did not show any strong reflection peaks in the 2theta regions 20 to 60∘ indicating the amorphous nature forCd(II) ion bound and unbound polymers

34 SEM-EDAX Thechemical composition of the imprintedand nonimprinted polymer networks were confirmed bySEM-EDAX The presence and complete removal of Cd(II)ion in imprinted and Cd(II) bound polymers respectivelywere confirmed by SEM-EDAX As shown in Figure 3 thesignal due to Cd(I1) was clearly presented for Cd(II) boundimprinted polymer but was absent in cadmium ion desorbedpolymer

0 1 2 3 4 5 6 7 8 9

(a)

0 1 2 3 4 5 6 7 8

Cd Cd

(b)

Figure 3 SEM-EDAX of Cd(II) ion (a) desorbed and (b) Cd(II)bound imprinted polymers

35 Thermogravimetric Analysis Thermogravimetric anal-ysis of imprinted nonimprinted and the correspondingCd(II) ion bound interpenetrating polymer networks revealsthe variation of thermal stability with Cd(II) ion binding(Figure 4) The thermal decomposition behavior of a metalion bound polymer depends on the macromolecular char-acteristics of the polymer support and the type of coordi-nation geometry [16] The decomposition of ion imprintedand nonimprinted polymers occurring at three stages andtheir corresponding Cd(II) ion bound polymer networksrequires two stages In all cases the first stage decompositioncorresponds to decomposition of the carboxylate group or


0 200 400 600 800 10000

20

40

60

80

100

Wei

ght (

)

(a) Imprinted polymer(b) Cd(II) bound polymer

(c) Cd(II) bound nonimprinted polymer(d) Nonimprinted polymer

(d)

(a)

(b)

(c)

Temperature (∘C)

Figure 4 TGA curves of Cd(II) ion imprinted nonimprinted andCd(II) ion bound IPNs

uncomplexed ligands The second stage is the major decom-position in which polymer chain breaks leaving only themetallic residue Thermogravimetric analysis of imprintedpolymer showed 15 weight loss at about 80ndash120∘C which isascribed to the removal of carboxylate group or uncomplexedligands During the second stage of decomposition at 300ndash400∘C 50 weight loss is observed which is attributed tothe decomposition of polymer chain while in Cd(II) boundpolymer the decomposition was in the range 150ndash500∘Cresulting in a mass loss of 55 Nonimprinted polymer net-works also decompose in a similar mannerThe temperaturesfor maximum weight loss (119879max) for imprinted polymer andCd (II) ion bound polymer networks were 310 and 390∘Crespectively From the Figure 4 it is clear that thermal stabilityof Cd(II) bound interpenetrating polymer networks is muchhigher than that of uncomplexed polymers

36 Swelling Studies The efficiency of a functional polymeris governed by the accessibility of the reactive functionalgroups anchored on it which in turn depends on theextent of swelling and solvation [17] The metal ion bindingstudies of the interpenetrating polymer networks in aqueousmedium were influenced by the extent of swelling A goodsolvent brings the crosslinked polymer to a state of completesolvation and the polymer network can expand to form agel The extent of swelling was dependent on the natureof the polymer backbone molecular character and extentof crosslinking agent The swelling behavior of Cd(II) ionimprinted and nonimprinted polymers and their corre-sponding Cd(II) bound polymer networks was investigated(Table 1) Maximum EWC () was obtained for Cd(II) ionimprinted polymer and it decreases on metal complexation

37 Binding Studies with Metal Ions The effect of initialconcentration of metal ion solution on its sorption was inves-tigated by varying the concentration of the metal ions such

Table 1 EWC () values of imprinted and nonimprinted polymersand their Cd(II) ion bound polymers

Polymers used EWC ()IIP 88NIP 86Cd(II) bound IIP 85Cd(II) bound NIP 84

1 2 3 4 500

02

04

06

08

Met

al b

ound

(meq

gm

)

Concentration (ppm) Cd-MIP Cd-NIP Cu-MIP Cu-NIP

Co-MIP Co-NIP Ni-MIP Ni-NIP

Figure 5 Effect of concentration ofmetal ion solution on its bindingby imprinted and nonimprinted polymers

as Cd(II) Co(II) Cu(II) and Ni(II) ions The imprinted andnonimprinted polymer networks (500mg) were equilibratedwith metal ion solution (1ndash5 ppm 10mL) the concentrationof template before and after binding was determined byatomic absorption spectrophotometry It was noted that asthe concentration increases binding of metal ion increases(Figure 5) This result could be explained on the basis ofa high driving force for mass transfer where the increasein concentration of metal ion increases the competition tooccupy all the available coordination sites in the adsorbent

38 Effect of Time on Metal Ion Binding To optimize thetime taken for maximum binding of Cd(II) ion by imprintedand nonimprinted polymer networks 100mg of polymernetworks was equilibrated with Cd(II) ion solution (10mL5 ppm) and the binding was followed by AAS at definiteintervals of timeThe time dependence of adsorption capaci-ties of Cd(II) ions on imprinted and nonimprinted polymerswas given in Figure 6 High adsorption rates were observedat the beginning of the adsorption process after whichadsorption equilibrium was quickly reached within 90minfor imprinted polymer network and 80min for nonimprintedpolymer network The imprinted polymer networks pos-sessing complementary binding site required more time to


0 20 40 60 80 10000

02

04

06

08

10

Cd(

II) b

ound

(meq

g)

Time (min) MIP NIP

Figure 6 Effect of time on Cd(II) ion binding by imprinted andnonimprinted polymers

attain saturation since the template metal ion has to pen-etrate through highly crosslinked interpenetrating polymernetworks In nonimprinted polymer networks there is nosuch specific arrangement of the binding sitesThemaximumadsorption capacity for Cd(II) ions was 087 meqgminus1 ofimprinted polymers This fast adsorption equilibrium is dueto high complexation rate and matching of the incomingCd(II) ions and Cd(II) cavities in the network structure

39 Effect of pH onMetal Ion Binding ThepH of themediumis one of the most important factors controlling the sorptionof metal ions by adsorbent The sorption of Cd(II) ionuptake at different pH was examined at equilibration byequilibrating imprinted and nonimprinted polymer (100mg)with (10mL 5 ppm) metal ion solution at varying pH andthe metal ion bound was determined by AAS Sorption ofmetal ion increases with increase in pH of the medium andthen decreases (Figure 7) It could be attributed to the factthat at low pH metal competition between the metal ionand the H+ ion favors protonation of carboxylate groupsthus lowering the metal ion binding But at higher pH of themedium the protonation decreases and as a result metal ionuptake increases

310 Sorption Studies The effect of concentration of Cd(II)ion solution on sorption rate and capacity was studied Defi-nite amounts of imprinted and nonimprinted polymers wereadded to fixed amount of Cd(II) ion solution (5 ppm) Thesolutions were shaken in closed flasks At regular intervals oftime Cd(II) ion boundwas determined byAASThe sorptioncharacteristics were assessed by plotting both Langmuirrsquosand Freundlichrsquos isotherms The Langmuir equation can bewritten as

119862119890

119902119890

=119862119890

119902119900

+1

119887119902119900

(3)

45 50 55 60 65 70

024

032

040

048

056

064

Cd(

II) b

ound

(meq

g)

pH IIP NIP

Figure 7 Effect of pH on Cd(II) ion binding

125 130 135 140 145 150 155

48

51

54

57

60

63

Concentration (ppm)

Ceq

(mg

L)

Figure 8 Langmuir isotherm of Cd(II) ion imprinted polymernetwork

where 119862119890

(mgLminus1) is the equilibrium concentration 119902119890

(meqgminus1) is the adsorption amount in equilibrium 119902119900

is themaximum adsorption amount and 119887 is the Langmuir con-stant related to adsorption capacity and energy of adsorption

For Langmuirrsquos isotherm 119862119890

119902119890

is plotted against 119862119890

and a straight line graph with 1198772 value 09984 was obtained(Figure 8)

Freundlichrsquos equation can be written as

log 119902119890

= log119870 + (1 minus 119899) log119862119890

(4)

where119870 is the Freundlichrsquos constant and 119899 is the Freundlichrsquosexponent

For Freundlichrsquos isotherm log 119902119890

is plotted againstlog119862119890

and a straight line graph with correlation coeffi-cient 0944 was obtained (Figure 9) By comparison of theadsorption isotherms of cadmium ion imprinted polymerwith Langmuirrsquos and Freundlichrsquos models it is found that

Advances in Environmental Chemistry 7ln

Qe

ln Ce

020 021 022 023 024 025

1320

1325

1330

1335

1340

1345

1350

1355

1360

Figure 9 Freundlichrsquos isotherm

the experimental data is in agreement with Langmuirrsquosisotherm better than that of Freundlichrsquos isotherm

311 Langmuir Isotherm See Figures 8 and 9

312 Effect of Temperature The effect of temperature on theadsorption processwas investigated for the adsorption of cad-mium ion on the imprinted polymer by batch equilibrationmethod and the amount of template bound at each temper-ature was determined by AAS The temperature was variedfrom 25 to 40∘C The obtained results showed that increasein temperature favours the sorption processThermodynamicparameters were calculated using the following equation

ln119870119889

= minusΔ119867119900

119877119879+Δ119878119900

119877 (5)

where

119870119889

=119876119890

119862119890

Δ119866119900

= Δ119867119900

minus 119879Δ119878119900

Δ119866119900

= minus119877119879 ln119870119889

(6)


119889

is the equilibrium constantWhen log119870

119889

is plotted against 119868119879 a straight line graphis obtained with slope minusΔ1198671199002303119877119879 and the values of Δ119867119900and Δ119878119900 were obtained from the slope and intercept of thevanrsquot Hoff plot (Figure 10) The values of Δ119867119900 Δ119866119900 and Δ119878119900for the plot shown in Figure 10 are found to be 1652 minus204kJmoleminus1 and 2326 kJmoleminus1Kminus1 The negative value of Δ119866119900indicates the feasibility and spontaneous nature of sorptionprocess The value of Δ119867119900 was positive indicating that thebinding was endothermic in nature and the positive value ofΔ119878119900 suggested an increase in randomness during the sorption

process

04

02

00

minus02

minus04

minus06

minus08

000

315

000

320

000

325

000

330

000

335

000

340

000

345

1T (K)

log K

d

Figure 10 The linear vanrsquot Hoff equation

5 10 15 20 25

02

03

04

05

06

07

t

tqt

Figure 11 Kinetic model of pseudosecond order

313 Sorption Kinetics The pseudosecond-order Lagergrenequation was used to describe the sorption kinetics of cad-mium ion imprinted IPN as described earlier The sorptionkinetics of cadmium ion imprinted IPN confirmed to thepseudosecond-order Lagergren equation with 1198772 = 0999(Figure 11) The value of 119870

2

calculated from the slope is00412minminus1

The pseudosecond-order Lagergren equation was used todescribe the adsorption kinetics of cadmium ion imprintedIPN Consider

119905

119902119905

= (1

1198702

1199022119890

+119905

119902119890

) (7)

where 1198702

(gmgminminus1) is the second-order Lagergren con-stant of adsorption and 119902

119905

(meqgminus1) and 119902119890

(meqgminus1) are thequantities of metal ions adsorbed at time 119905 (min) and at equi-librium respectively The adsorption kinetics of cadmiumion imprinted IPN was confirmed to the pseudosecond-order Lagergren equation with 1198772 = 0999 The value of 119870

2

calculated from the slope is 00412minminus1


Table 2 Selectivity parameters of Cd(II) ion imprinted polymers

Metal ions 120572119894

120572119899

120572119903

Cd(II) Zn(II) 190 030 630Cd(II) Ni(II) 164 101 162Cd(II) Mn(II) 106 071 151Cd(II) Cu(II) 101 092 111Cd(II) Co(II) 101 085 118

314 Selectivity Experiments The selectivity of the imprintedpolymer for Cd(II) ion was investigated by rebinding Cd(II)ion in presence of various competitor metal ions (Figure 12)Some important parameters including adsorption capacitydistribution ratio selectivity factor of Cd(II) ion with respectto the other ions and relative selectivity factorwere calculated(Table 2) from the following equations

120572 =119863Cd119863119872

119863 =119876

119862119890

120572119903

=120572119894

120572119899

(8)

where 119876 represents the sorption capacity (meqgminus1) and 119862119890

is the equilibrium concentration of metal ions (mg Lminus1)119863Cd and 119863

119872

(mLgminus1) represent the distribution ratios ofCd(II) and other competitive ions respectively 120572

119903

120572119894

and120572119899

represent the relative selectivity coefficient the selectivityfactor of imprinted sorbent and the selectivity factor ofnonimprinted sorbent respectively

To investigate the Cd(II) ion selectivity of the imprintedpolymer networks competitive sorption of Mn(II) Co(II)Ni(II) Cu(II) and Zn(II) ions was carried out by columnexperiment in which 1 g of imprinted polymer was treatedwith (10mL 5 ppm) solution of these metal ions After sorp-tion equilibriumwas reached the concentration ofmetal ionsin the remaining solution was measured by AAS The func-tional host molecules on the imprinted polymer networksare immobilized with the strict configuration suitable forcadmium ions and the ionic recognition is influenced by thenature of metal ion and ionic radius and charge The resultsrevealed that Cd(II) ion imprinted polymer networks showedhigh selectivity towards cadmium ion from cadmium-zincmixture and maximum separation is obtained dependingon the selectivity coefficient In cadmium-copper mixturelow selectivity coefficient value is obtained But from thecadmium-nickel mixture the ion imprinted polymer showedconsiderable selectivity (Figure 12)

315 Reusability Studies Reusability of cadmium ionimprinted polymers was investigated by elution operationsand the results are given in Figure 13 The elution operationswere carried out with 4mL of HCl (3N) and found as theoptimum elution condition The calculated percent recoveryof the imprinted polymer showed no considerable decrease

Cd Cu Cd Zn Cd Co Cd Mn Cd Ni00020406081012141618

Met

al io

n bo

und

(meq

sgm

)

Metal ions

Cd(II) Competing metal ion

Figure 12 Summary of the selectivity study of Cd(II) ion imprintedinterpenetrating polymer networks

1 2 3 4 5 6 7 800

02

04

06

08C

d(II

) ion

bou

nd (m

eqg

)

Number of cycles

Figure 13 Reusability studies of Cd(II) ion binding by IIP

after 8 cycles of repeated experiments The percentagerecovery of the recycled IIP could still be maintained at98 at the 8th cycle It can be concluded that the Cd(II)ion imprinted polymer can be used for many times withoutsignificant decrease in its sorption capacity

316 Analytical Precision and Detection Limits Under theselected conditions eight portions of standard solutions wereenriched and analyzed simultaneously following the generalprocedure The relative standard deviations (R S D) ofthe method was lower than 22 which indicated that themethod had good precision for the analysis of trace Cd(II)ion in solution samples In accordance with the definition ofIUPAC the detectionlimit of themethodwascalculated basedon three times of the standard deviation of 11 runs of the blanksolution The detection limit (3120590) of the proposed methodwas 034 ngsdotmLminus1


Table 3 Comparative study of the Cd(II)IIP

Monomer Polymerization technique Adsorption capacity (meqg) ReferenceEpoxy resin triethylene tetra amine Copolymerization 00934 722-ethane-12-diylbis[nitrilo(E)metylylidene]diphenolate4-vinylpyridine Suspension polymerization 00042 18

Alginic acid acrylamide netwok Free-radical polymerization 0217 This study

Table 4 Analysis of environmental water samples

Cd(II) ion Lake water (mgL) Canal waterFound 0047 0035Removed 0043 0034Recovered () 98 99

317 Comparison with Other Studied Polymers In the lit-erature various ion imprinted polymers have been studiedwith a wide range of sorption capacities for Cd(II) ions Theresults of this study are compared with them in Table 3 Thesorption capacities of the present polymers are varied in therange of 02-03meqgminus1 from aqueous solutions Thereforethe newly developed biosorbent exhibited better capacityvalues in comparison to most of the other alginic acid basedand natural polymer sorbents

318 Application of the Method The synthesized IPN wasapplied to the analysis of Cd(II) ion in environmental watersamples collected from Vembanad lake and nearby canalsThe samples were treated by the same procedureThe sampleswere introduced into the cadmium ion imprinted polymer bycolumn method and analysed by AAS The results obtainedindicate the suitability of the present Cd(II) ion imprintedIPN for the removal of hazardous Cd(II) ion from environ-mental water samples The results were listed in Table 4

4 Conclusions

Thepresent paper demonstrates the preparation of Cd(II) ionimprinted and nonimprinted interpenetrating polymer net-works using functional polymer alginic acid and NNMBA-crosslinked polyacrylamide The synthesised imprinted andnonimprinted interpenetrating polymer networks were char-acterized by FT-IR UV-vis SEM-EDAX XRD and TGAThe Cd(II) ion sorption was relatively fast The maximumsorption capacity for Cd(II) ions was 08861meqmoleminus1 ofimprinted polymer The fast sorption equilibrium is mostprobably due to high complexation and geometric affinitybetween Cd(II) ions and the cavities in the network structureThe sorption values increased with increasing concentrationof Cd(II) ions Langmuir model was found to be applicable ininterpreting Cd(II) ion sorption on the Cd(II) ion imprintedpolymer and the adsorption kinetics was described bythe pseudosecond-order kinetic model Maximum swellingwas obtained for Cd(II) ion imprinted and nonimprintedpolymers rather than imprinted complexes The sorptionvalues increased with increase in pH and a saturation value

was obtained at pH 69 Thermodynamic parameters werecalculated using the vanrsquot Hoff equation and the sorption ofCd(II) ion on imprinted polymer networks was spontaneousand endothermic in nature and entropy of sorption increasesduring the reaction Cd(II) ion imprinted interpenetratingpolymer networks exhibited much high selectivity The ana-lytical results obtained in these investigations suggested thatthe sorbent may be used as an inexpensive and effectivepolymer for the removal of cadmium ion from aqueoussolution and was successfully applied for the separation ofCd(II) ion from environmental water samples

Conflict of Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper

Acknowledgment

The author Girija Parameswaran thanks UGC Bangalore forproviding a Teacher Fellowship

References

[1] L D Mafu T A M Msagati and B B Mamba ldquoIon-imprinted polymers for environmental monitoring of inorganicpollutants synthesis characterization and applicationsrdquo Envi-ronmental Science and Pollution Research vol 20 no 2 pp 790ndash802 2013

[2] F Aboufazeli H Zhad O Sadeghi M Karimi and E NajafildquoNovel Cd(II) ion imprinted polymer coated on multiwallcarbon nanotubes as a highly selective sorbent for cadmiumdetermination in food samplesrdquo Journal of AOAC Internationalvol 97 no 1 pp 173ndash178 2014

[3] J H Kim S B Lee S J Kim and Y M Lee ldquoRapidtemperaturepH response of porous alginate-g-poly(N-isopropylacrylamide) hydrogelsrdquo Polymer vol 43 no 26 pp7549ndash7558 2002

[4] H G Seiler A Sigel and H Sigel Handbook on Toxicity ofInorganic Compounds Marcel Dekker New York NY USA1998

[5] Y Zhai Y Liu X Chang S Chen and X Huang ldquoSelectivesolid-phase extraction of trace cadmium(II) with an ionicimprinted polymer prepared from a dual-ligand monomerrdquoAnalytica Chimica Acta vol 593 no 1 pp 123ndash128 2007

[6] K Lu and X P Yan ldquoAn imprinted organic-inorganic hybridsorbent for selective separation of cadmium from aqueoussolutionrdquoAnalytical Chemistry vol 76 no 2 pp 453ndash457 2004

[7] J Pan S Wang and R Zhang ldquoIon-imprinted interpenetratingpolymer networks for preconcentration and determination


of Cd(II) by flame atomic absorption spectrometryrdquo ChemiaAnalityczna vol 51 no 5 pp 701ndash713 2006

[8] S E Manahan Environmental Chemistry Lewis PublishersBoca Raton Fla USA 6th edition 1994

[9] J S Watson Separation Methods for Waste and EnvironmentalApplications Marcel Dekker New York NY USA 1999

[10] A Martinsen G Skjak-Braek and O Smidsrod ldquoAlginate asimmobilization material I Correlation between chemical andphysical properties of alginate gel beadsrdquo Biotechnology andBioengineering vol 33 no 1 pp 79ndash89 1989

[11] D Solpan and M Torun ldquoInvestigation of complex formationbetween (sodium alginateacrylamide) semi-interpenetratingpolymer networks and lead cadmium nickel ionsrdquoColloids andSurfaces A Physicochemical and Engineering Aspects vol 268no 1ndash3 pp 12ndash18 2005

[12] T Alizadeh ldquoAn imprinted polymer for removal of Cd2+ fromwater samples optimization of adsorption and recovery stepsby experimental designrdquoChinese Journal of Polymer Science vol29 no 6 pp 658ndash669 2011

[13] S Ozkara M Andac and V Karakoc ldquoIon-imprinted PHEMAbased monolith for the removal of Fe3+ ions from aqueoussolutionsrdquo Journal of Applied Polymer Science vol 120 no 3 pp1829ndash1836 2011

[14] P Fan and B Wang ldquoRegulatory effects of Zn(II) on the recog-nition properties of metal coordination imprinted polymersrdquoJournal of Applied Polymer Science vol 116 no 1 pp 258ndash2662010

[15] N Burham A Mamdouh and M F EL-Sahat ldquoSeparation anddetermination ofCd2+ Pb2+ andCu2+ fromwater samples usingchemically modified groundnut shellsrdquo International Journal ofAdvanced Research vol 2 no 1 pp 755ndash765 2014

[16] B George V N R Pillai and B Mathew ldquoEffect of thenature of the crosslinking agent on the metal-ion complexationcharacteristics of 4mol DVB- and NNMBA-crosslinkedpolyacrylamide-supported glycinesrdquo Journal of Applied PolymerScience vol 74 no 14 pp 3432ndash3444 1999

[17] N Sebastian B George and B Mathew ldquoMetal complexes ofpoly(acrylic acid) synthesis characterization and thermogravi-metric studiesrdquo Polymer Degradation and Stability vol 60 no2-3 pp 371ndash375 1998

Submit your manuscripts athttpwwwhindawicom

Forestry ResearchInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Environmental and Public Health

Journal of



EcosystemsJournal of


MeteorologyAdvances in

EcologyInternational Journal of


Marine BiologyJournal of


Hindawi Publishing Corporationhttpwwwhindawicom

Applied ampEnvironmentalSoil Science

Volume 2014

Advances in


Environmental Chemistry

Atmospheric SciencesInternational Journal of



Waste ManagementJournal of

Hindawi Publishing Corporation httpwwwhindawicom Volume 2014

International Journal of

Geophysics


Geological ResearchJournal of

EarthquakesJournal of


BiodiversityInternational Journal of


ScientificaHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

OceanographyInternational Journal of


The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Journal of Computational Environmental SciencesHindawi Publishing Corporationhttpwwwhindawicom Volume 2014


ClimatologyJournal of


pollutant list of the Environmental Protection Agency (EPA)[8] Alginate is one of the most extensively investigatedbiopolymer for the removal of heavymetal ions from aqueoussolutions [9ndash11]There have been few reports on the synthesisof ion imprinted polymers for removal of Cd(II) from watersamples [12ndash15] Thus the extraction preconcentration anddetermination of trace cadmium from the natural water arevery important and need much more attention

In the present study we aim to fabricate a noveltype of Cd(II) ion imprinted interpenetrating polymer net-work using a natural biosorbent alginic acid which iscrosslinked by the hydrophilic crosslinker NN1015840 methylene-bis-acrylamide and template Cd(II) ion The hydrophilicnature of crosslinker increased the swelling ability of poly-mer network which favours effective cadmium ion bindingThe newly prepared interpenetrating polymer network isadvantageous because it showed high sorption capacity andremarkable selectivity in Cd(II) ion separation from mixtureof metal ions Compared to the previous reports the presentIIP showed high sorption capacity and good reusability forCd(II) ion and the synthesis of IIP involves clean technologyand can be used for waste water treatment The biopolymersare capable of removing metal ions The method of prepara-tion of the IPN can be considered as ldquogreenrdquo and also simplerapid low cost and environment friendly due to the use ofaqueous medium

2 Materials and Methods

Reagents of analytical and spectral grade were used for allexperiments Cadmium acetate used in the present study isof analytical grade (99 pure) and solutions were preparedby dissolving the required quantity of CdCH

3

(COO)2

inmillipore water The monomers used in this study namelyacrylamide (999 pure) and crosslinking agent NNMBAwere obtained from SRL (Mumbai) Alginic acid (985pure) was obtained from Merk (India) Fourier transforminfrared (FT-IR) spectra of the imprinted nonimprintedand the Cd(II) ion bound polymer networks were recordedbetween 4000 and 400 cmminus1 using a Perkin Elmer 400 FT-IR spectrophotometer and far IR spectra of Cd(II) ion boundpolymer networks were recorded between 400 and 100 cmminus1using the same instrument UV-vis spectrophotometric mea-surements were carried out using Shimadzu 2400UV-visspectrophotometer SEM-EDAX were taken on JEOL-JSM-840A scanning electron microscope in nitrogen atmosphereTG curves were recorded on a Shimadzu D-740 thermalanalyser at a heating rate of 10∘C min from 20 to 900∘C innitrogen atmosphere The amount of metal ion sorbed pergram of imprinted and nonimprinted polymers from metalion solutions was determined using Perkin Elmer atomicabsorption analyzer 300

21 Preparation of Cd(II) Ion Imprinted (IIP) and Non-imprinted (NIP) Polymer Networks Alginic acid (75 g)was mixed with (064 g) of cadmium acetate in aqueousmedium This mixture was added to an aqueous solutionof acrylamide (1066 g) and NN-methylenebisacrylamide

(NNMBA) (771 g) and kept at 70∘C in a water bath withstirring using potassium persulphate (100mg) as initiatorThe polymer obtained was washed with water to removeunreacted monomer and with 2N HCl to remove Cd(II) ionThe bulk polymer obtained was dried sieved and weighedNonimprinted polymer networks were also prepared usingthe same procedure without metal ions

22Metal Ion Binding In order to investigate specific rebind-ing capacity Cd(II) ion imprinted and nonimprinted poly-mers (500mg) were equilibrated with Cd(II) Co(II) Cu(II)and Ni(II) (1ndash5 ppm 10mL) ion solution The concentrationof template metal ion solution before and after binding wasdetermined by atomic absorption spectrophotometry (AAS)

23 Swelling Studies 100mg of Cd(II) ion imprinted non-imprinted and corresponding Cd(II) bound polymers wasallowed to swell in 10mL water for 24 h After 24 h thepolymers were filtered and surface water was carefully wipedoff and the final swollen weight was determined From theswollen and the dry weights of the sample the EWC () wascalculated using the following equation

EWC ()

=weight of wet polymer minus weight of dry polymer

weight of dry polymertimes 100

(1)

24 Optimization of the Cd(II) Ion Rebinding Conditions Inorder to optimize the conditions of Cd(II) ion rebindingby imprinted and nonimprinted polymers factors affectingrebinding such as effect of concentration time and pH of theCd(II) ion solution on binding were investigated

25 Effect of Concentration The batch-wise metal ion bind-ing experimentswere carried out using (500mg) of imprintedand nonimprinted polymer to evaluate the effect of concen-tration of template solution on rebinding

From the difference in concentration of template solutionbefore and after incubation the amount of Cd(II) ion boundwas determined Similar rebinding studies at various concen-trations of metal ion (1ndash5 ppm 10mL) were carried out andanalyzed by AAS

26 Effect of Time The time required for maximum bindingwas determined by batch equilibration method 500mg ofimprinted and nonimprinted polymers was equilibrated with(5 ppm 10mL) of Cd(II) ion solution and metal ion boundwas determined at regular intervals of time and analyzed byAAS

27 Effect of pH on Cd(II) Ion Binding About 100mg ofimprinted and nonimprinted polymers was equilibrated withCd(II) ion (5 ppm 10mL) at different pH After the removalof polymer particles the amounts of Cd(II) ion bound at eachpH were determined by AAS





ln119870119889

= minusΔ119867119900

119877119879+Δ119878119900

119877 (2)


119889





300 400 500 600 700 80002

04

06

08

10

b

a

Abso

rban

ce

Wavelength (nm)







NNMBAO O

N NH H

AcrylamideO

NH2

K2S2O8 70∘C

Alginic acid

IIP

M++ M++

M++

OO

O OO

O

OHO HO

OH

OHOHOH

n

m


0 10 20 30 40 50 60 70

10

20

30

40

50

60

70

80



Inte

nsity

(au

)

2120579 (deg)




0 1 2 3 4 5 6 7 8 9

(a)

0 1 2 3 4 5 6 7 8

Cd Cd

(b)




0 200 400 600 800 10000

20

40

60

80

100

Wei

ght (

)



(d)

(a)

(b)

(c)

Temperature (∘C)







1 2 3 4 500

02

04

06

08

Met

al b

ound

(meq

gm

)







0 20 40 60 80 10000

02

04

06

08

10

Cd(

II) b

ound

(meq

g)

Time (min) MIP NIP





119862119890

119902119890

=119862119890

119902119900

+1

119887119902119900

(3)

45 50 55 60 65 70

024

032

040

048

056

064

Cd(

II) b

ound

(meq

g)

pH IIP NIP


125 130 135 140 145 150 155

48

51

54

57

60

63

Concentration (ppm)

Ceq

(mg

L)


where 119862119890





119902119890




log 119902119890

= log119870 + (1 minus 119899) log119862119890

(4)






Qe

ln Ce

020 021 022 023 024 025

1320

1325

1330

1335

1340

1345

1350

1355

1360





ln119870119889

= minusΔ119867119900

119877119879+Δ119878119900

119877 (5)

where

119870119889

=119876119890

119862119890

Δ119866119900

= Δ119867119900

minus 119879Δ119878119900

Δ119866119900

= minus119877119879 ln119870119889

(6)


119889


119889


process

04

02

00

minus02

minus04

minus06

minus08

000

315

000

320

000

325

000

330

000

335

000

340

000

345

1T (K)

log K

d


5 10 15 20 25

02

03

04

05

06

07

t

tqt



2



119905

119902119905

= (1

1198702

1199022119890

+119905

119902119890

) (7)

where 1198702


119905



2




Metal ions 120572119894

120572119899

120572119903



120572 =119863Cd119863119872

119863 =119876

119862119890

120572119903

=120572119894

120572119899

(8)



119872


119903

120572119894

and120572119899





Met

al io

n bo

und

(meq

sgm

)

Metal ions



1 2 3 4 5 6 7 800

02

04

06

08C

d(II

) ion

bou

nd (m

eqg

)

Number of cycles












4 Conclusions





Acknowledgment


References
























Journal of












Volume 2014

Advances in









Geophysics


















ln119870119889

= minusΔ119867119900

119877119879+Δ119878119900

119877 (2)


119889





300 400 500 600 700 80002

04

06

08

10

b

a

Abso

rban

ce

Wavelength (nm)







NNMBAO O

N NH H

AcrylamideO

NH2

K2S2O8 70∘C

Alginic acid

IIP

M++ M++

M++

OO

O OO

O

OHO HO

OH

OHOHOH

n

m


0 10 20 30 40 50 60 70

10

20

30

40

50

60

70

80



Inte

nsity

(au

)

2120579 (deg)




0 1 2 3 4 5 6 7 8 9

(a)

0 1 2 3 4 5 6 7 8

Cd Cd

(b)




0 200 400 600 800 10000

20

40

60

80

100

Wei

ght (

)



(d)

(a)

(b)

(c)

Temperature (∘C)







1 2 3 4 500

02

04

06

08

Met

al b

ound

(meq

gm

)







0 20 40 60 80 10000

02

04

06

08

10

Cd(

II) b

ound

(meq

g)

Time (min) MIP NIP





119862119890

119902119890

=119862119890

119902119900

+1

119887119902119900

(3)

45 50 55 60 65 70

024

032

040

048

056

064

Cd(

II) b

ound

(meq

g)

pH IIP NIP


125 130 135 140 145 150 155

48

51

54

57

60

63

Concentration (ppm)

Ceq

(mg

L)


where 119862119890





119902119890




log 119902119890

= log119870 + (1 minus 119899) log119862119890

(4)






Qe

ln Ce

020 021 022 023 024 025

1320

1325

1330

1335

1340

1345

1350

1355

1360





ln119870119889

= minusΔ119867119900

119877119879+Δ119878119900

119877 (5)

where

119870119889

=119876119890

119862119890

Δ119866119900

= Δ119867119900

minus 119879Δ119878119900

Δ119866119900

= minus119877119879 ln119870119889

(6)


119889


119889


process

04

02

00

minus02

minus04

minus06

minus08

000

315

000

320

000

325

000

330

000

335

000

340

000

345

1T (K)

log K

d


5 10 15 20 25

02

03

04

05

06

07

t

tqt



2



119905

119902119905

= (1

1198702

1199022119890

+119905

119902119890

) (7)

where 1198702


119905



2




Metal ions 120572119894

120572119899

120572119903



120572 =119863Cd119863119872

119863 =119876

119862119890

120572119903

=120572119894

120572119899

(8)



119872


119903

120572119894

and120572119899





Met

al io

n bo

und

(meq

sgm

)

Metal ions



1 2 3 4 5 6 7 800

02

04

06

08C

d(II

) ion

bou

nd (m

eqg

)

Number of cycles












4 Conclusions





Acknowledgment


References
























Journal of












Volume 2014

Advances in









Geophysics















NNMBAO O

N NH H

AcrylamideO

NH2

K2S2O8 70∘C

Alginic acid

IIP

M++ M++

M++

OO

O OO

O

OHO HO

OH

OHOHOH

n

m


0 10 20 30 40 50 60 70

10

20

30

40

50

60

70

80



Inte

nsity

(au

)

2120579 (deg)




0 1 2 3 4 5 6 7 8 9

(a)

0 1 2 3 4 5 6 7 8

Cd Cd

(b)




0 200 400 600 800 10000

20

40

60

80

100

Wei

ght (

)



(d)

(a)

(b)

(c)

Temperature (∘C)







1 2 3 4 500

02

04

06

08

Met

al b

ound

(meq

gm

)







0 20 40 60 80 10000

02

04

06

08

10

Cd(

II) b

ound

(meq

g)

Time (min) MIP NIP





119862119890

119902119890

=119862119890

119902119900

+1

119887119902119900

(3)

45 50 55 60 65 70

024

032

040

048

056

064

Cd(

II) b

ound

(meq

g)

pH IIP NIP


125 130 135 140 145 150 155

48

51

54

57

60

63

Concentration (ppm)

Ceq

(mg

L)


where 119862119890





119902119890




log 119902119890

= log119870 + (1 minus 119899) log119862119890

(4)






Qe

ln Ce

020 021 022 023 024 025

1320

1325

1330

1335

1340

1345

1350

1355

1360





ln119870119889

= minusΔ119867119900

119877119879+Δ119878119900

119877 (5)

where

119870119889

=119876119890

119862119890

Δ119866119900

= Δ119867119900

minus 119879Δ119878119900

Δ119866119900

= minus119877119879 ln119870119889

(6)


119889


119889


process

04

02

00

minus02

minus04

minus06

minus08

000

315

000

320

000

325

000

330

000

335

000

340

000

345

1T (K)

log K

d


5 10 15 20 25

02

03

04

05

06

07

t

tqt



2



119905

119902119905

= (1

1198702

1199022119890

+119905

119902119890

) (7)

where 1198702


119905



2




Metal ions 120572119894

120572119899

120572119903



120572 =119863Cd119863119872

119863 =119876

119862119890

120572119903

=120572119894

120572119899

(8)



119872


119903

120572119894

and120572119899





Met

al io

n bo

und

(meq

sgm

)

Metal ions



1 2 3 4 5 6 7 800

02

04

06

08C

d(II

) ion

bou

nd (m

eqg

)

Number of cycles












4 Conclusions





Acknowledgment


References
























Journal of












Volume 2014

Advances in









Geophysics















0 200 400 600 800 10000

20

40

60

80

100

Wei

ght (

)



(d)

(a)

(b)

(c)

Temperature (∘C)







1 2 3 4 500

02

04

06

08

Met

al b

ound

(meq

gm

)







0 20 40 60 80 10000

02

04

06

08

10

Cd(

II) b

ound

(meq

g)

Time (min) MIP NIP





119862119890

119902119890

=119862119890

119902119900

+1

119887119902119900

(3)

45 50 55 60 65 70

024

032

040

048

056

064

Cd(

II) b

ound

(meq

g)

pH IIP NIP


125 130 135 140 145 150 155

48

51

54

57

60

63

Concentration (ppm)

Ceq

(mg

L)


where 119862119890





119902119890




log 119902119890

= log119870 + (1 minus 119899) log119862119890

(4)






Qe

ln Ce

020 021 022 023 024 025

1320

1325

1330

1335

1340

1345

1350

1355

1360





ln119870119889

= minusΔ119867119900

119877119879+Δ119878119900

119877 (5)

where

119870119889

=119876119890

119862119890

Δ119866119900

= Δ119867119900

minus 119879Δ119878119900

Δ119866119900

= minus119877119879 ln119870119889

(6)


119889


119889


process

04

02

00

minus02

minus04

minus06

minus08

000

315

000

320

000

325

000

330

000

335

000

340

000

345

1T (K)

log K

d


5 10 15 20 25

02

03

04

05

06

07

t

tqt



2



119905

119902119905

= (1

1198702

1199022119890

+119905

119902119890

) (7)

where 1198702


119905



2




Metal ions 120572119894

120572119899

120572119903



120572 =119863Cd119863119872

119863 =119876

119862119890

120572119903

=120572119894

120572119899

(8)



119872


119903

120572119894

and120572119899





Met

al io

n bo

und

(meq

sgm

)

Metal ions



1 2 3 4 5 6 7 800

02

04

06

08C

d(II

) ion

bou

nd (m

eqg

)

Number of cycles












4 Conclusions





Acknowledgment


References
























Journal of












Volume 2014

Advances in









Geophysics















0 20 40 60 80 10000

02

04

06

08

10

Cd(

II) b

ound

(meq

g)

Time (min) MIP NIP





119862119890

119902119890

=119862119890

119902119900

+1

119887119902119900

(3)

45 50 55 60 65 70

024

032

040

048

056

064

Cd(

II) b

ound

(meq

g)

pH IIP NIP


125 130 135 140 145 150 155

48

51

54

57

60

63

Concentration (ppm)

Ceq

(mg

L)


where 119862119890





119902119890




log 119902119890

= log119870 + (1 minus 119899) log119862119890

(4)






Qe

ln Ce

020 021 022 023 024 025

1320

1325

1330

1335

1340

1345

1350

1355

1360





ln119870119889

= minusΔ119867119900

119877119879+Δ119878119900

119877 (5)

where

119870119889

=119876119890

119862119890

Δ119866119900

= Δ119867119900

minus 119879Δ119878119900

Δ119866119900

= minus119877119879 ln119870119889

(6)


119889


119889


process

04

02

00

minus02

minus04

minus06

minus08

000

315

000

320

000

325

000

330

000

335

000

340

000

345

1T (K)

log K

d


5 10 15 20 25

02

03

04

05

06

07

t

tqt



2



119905

119902119905

= (1

1198702

1199022119890

+119905

119902119890

) (7)

where 1198702


119905



2




Metal ions 120572119894

120572119899

120572119903



120572 =119863Cd119863119872

119863 =119876

119862119890

120572119903

=120572119894

120572119899

(8)



119872


119903

120572119894

and120572119899





Met

al io

n bo

und

(meq

sgm

)

Metal ions



1 2 3 4 5 6 7 800

02

04

06

08C

d(II

) ion

bou

nd (m

eqg

)

Number of cycles












4 Conclusions





Acknowledgment


References
























Journal of












Volume 2014

Advances in









Geophysics















Qe

ln Ce

020 021 022 023 024 025

1320

1325

1330

1335

1340

1345

1350

1355

1360





ln119870119889

= minusΔ119867119900

119877119879+Δ119878119900

119877 (5)

where

119870119889

=119876119890

119862119890

Δ119866119900

= Δ119867119900

minus 119879Δ119878119900

Δ119866119900

= minus119877119879 ln119870119889

(6)


119889


119889


process

04

02

00

minus02

minus04

minus06

minus08

000

315

000

320

000

325

000

330

000

335

000

340

000

345

1T (K)

log K

d


5 10 15 20 25

02

03

04

05

06

07

t

tqt



2



119905

119902119905

= (1

1198702

1199022119890

+119905

119902119890

) (7)

where 1198702


119905



2




Metal ions 120572119894

120572119899

120572119903



120572 =119863Cd119863119872

119863 =119876

119862119890

120572119903

=120572119894

120572119899

(8)



119872


119903

120572119894

and120572119899





Met

al io

n bo

und

(meq

sgm

)

Metal ions



1 2 3 4 5 6 7 800

02

04

06

08C

d(II

) ion

bou

nd (m

eqg

)

Number of cycles












4 Conclusions





Acknowledgment


References
























Journal of












Volume 2014

Advances in









Geophysics
















Metal ions 120572119894

120572119899

120572119903



120572 =119863Cd119863119872

119863 =119876

119862119890

120572119903

=120572119894

120572119899

(8)



119872


119903

120572119894

and120572119899





Met

al io

n bo

und

(meq

sgm

)

Metal ions



1 2 3 4 5 6 7 800

02

04

06

08C

d(II

) ion

bou

nd (m

eqg

)

Number of cycles












4 Conclusions





Acknowledgment


References
























Journal of












Volume 2014

Advances in









Geophysics






















4 Conclusions





Acknowledgment


References
























Journal of












Volume 2014

Advances in









Geophysics






























Journal of












Volume 2014

Advances in









Geophysics














research article bioremediation of waste water containing...

Documents