absorbed pb2+ and cd2+ ions in water by cross-linked...

Research ArticleAbsorbed Pb2+ and Cd2+ Ions in Water byCross-Linked Starch Xanthate

Kai Feng and Guohua Wen

College of Chemistry and Chemical Engineering Inner Mongolia University Hohhot 010021 China

Correspondence should be addressed to Guohua Wen wenguohua1961126com

Received 27 November 2016 Accepted 5 December 2016 Published 3 January 2017

Academic Editor Marta Fernandez-Garcıa

Copyright copy 2017 K Feng and G WenThis 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

A cross-linked starch xanthate was prepared by graft copolymerization of acrylamide and sodium acrylate onto starch xanthateusing potassium persulfate and sodium hydrogen sulfite initiating system and NN1015840-methylenebisacrylamide as a cross-linker Asthis kind of cross-linked potato starch xanthate can effectively absorb heavy metal ions it was dispersed in aqueous solutions ofdivalent heavy metal ions (Pb2+ and Cd2+) to investigate their absorbency by the polymer Factors that can influence absorbencywere investigated such as the ratio of matrix to monomers the amount of initiator and cross-linker pH and the concentrationof metal ions Results were reached and conclusion was drawn that the best synthetic conditions for the polymer adsorbing Pb2+and Cd2+ were as follows the quality ratio of matrix to monomers was 1 12 and 1 11 the amount of initiator was 24 and 32of matrix and the amount of cross-linker was 12mg and 13mg When the initial concentration of ions was 10mgL the highestquantities of adsorption of Pb2+ and Cd2+ were 4711mgg and 3655mgg Adsorption mechanism was discussed by using Fouriertransform infrared (FTIR) spectroscopy X-ray diffraction (XRD) scanning electron microscope (SEM) Energy Dispersive X-RaySpectroscopy (EDS) test and adsorption kinetic simulation

1 Introduction

Modern society is perplexed with water pollution especiallypollution caused by heavy metals It is vital to remove heavymetals such as lead cadmium copper and mercury beforethey are drained into the ecosystem as it will be of greatdifficulty to remove them from food chains and extremelytoxic living organisms [1] Several techniques have beenutilized for the removal of heavy metals from water suchas precipitation flotation solvent extraction adsorptionmembrane processing and electrolysis [2] Adsorption withadvantages of high efficiency easy handling and availabilityof different adsorbents is generally preferred Studies makeefforts to search for cost-effective adsorbents Among thevarious absorbents starch has been considered as one of thebest choices for the preparation of low-cost absorbents andcan be used for the separation of pollutants from waste water[3 4]

Adsorbents based on starch are receiving increasingattention since starch is abundant renewable and biodegrad-able However the hydrophilic nature of starch is a major

drawback that limits the development of starch-based mate-rials [5] Previous studies have shown that some starchderivatives may be effective in removing heavy metals fromwater For example Kweon et al [6] investigated the adsorp-tion of divalent metal ions by succinylated and oxidizedcorn starches Xu et al [7] studied the adsorption processof Pb2+ by cross-linked amphoteric starch with quaternaryammonium and carboxymethyl groups and Popuri et al [8]investigated cross-linked starch graft copolymers containingamine groups as the adsorbents for Pb2+ and Cu2+

The modified starch is nontoxic and biodegradable withlow cost Starch can be modified by several ways and thepreparation of cross-linked starch is widely used becauseit contains many functional groups such as -COOH -OH-SO3H -CONH2 etc that have strong chelating ability withheavy mrtal ions Therefore the cross-linked starch materialscan be used on adsorption of heavy metal ions meaningimportant values on helping solve current environmentalproblemsmdashwater pollution caused by the heavy metal dis-charges [9 10]

HindawiInternational Journal of Polymer ScienceVolume 2017 Article ID 6470306 9 pageshttpsdoiorg10115520176470306

2 International Journal of Polymer Science

In this study we describe the use of cross-linked starchxanthate as a complexing agent that can absorb Pb2+ andCd2+ through grafted copolymerization with acrylamide andsodium acrylate and focus on its adsorption properties andits potential for recycling the heavy metal ions

2 Experimental Section

21 Materials Potato starch food grade was purchased fromInner Mongolia Ke Xinyuan Co Ltd China The sodiumhydroxide was obtained from Tianjin North Fine ChemicalsCo Ltd China Carbon disulfide was purchased fromChineseMedicine Group Chemical Reagent Co Ltd ChinaAbsolute ethanol was purchased from Tianjin North FineChemicals Co Ltd China Acrylic acid was purchased fromChineseMedicine Group Chemical Reagent Co Ltd ChinaAcrylamide was obtained from Chinese Medicine GroupChemical Reagent Co Ltd China Potassium persulfatewas purchased from Chinese Medicine Group ChemicalReagent Co Ltd China The sodium bisulfite was obtainedfrom Tianjin North Fine Chemicals Co Ltd China NN1015840-Methylenebisacrylamide was purchased from Beijing Chem-ical Reagent Company Co Ltd China All the aboveingredients except potato starch were of analytical grades

22 Preparation of Starch Xanthate 50 g native starch wasdispersed in 25mL of distilled water and the concentration of14 sodium hydroxide solution was added to the resultingslurry in room temperature Then 35mL carbon disulfidewas added to the system To control the reaction temperaturethe reactor was placed in a water bath preset at 30∘C for 2 h

The reaction product was precipitated in an excess ofethanol and separated by filtration Then we dried it in avacuum oven at 40∘C for two days Moreover the desiredstarch xanthatewasmilled and sifted through a 60-mesh sieveto prepare samples

23 Synthesis of Cross-Linked Starch Xanthate 25 g starchxanthate was dispersed in 50mL of distilled water and stirredfor a period of time then 40mL sodium acrylate and aselected amount of acrylamide were poured into the solutionfollowed by potassium persulfate (20mgmL) and a selectedamount of NN1015840-methylenebisacrylamide They were reactedunder a nitrogen gas atmosphere by heating the solution asto make graft copolymerization reaction occur The productwas dried for 12 h and finally ground to powder

24Metal Adsorption and Procedure forQuantitative AnalysisAqueous solutions of Pb2+ (Pb 10mgL) and Cd2+ (Cd10mgL) ions were prepared by dissolving 07993 g Pb(NO3)2and 06861 g Cd(NO3)2sdot4H2O in 500mL deionized water02 g cross-linked starch xanthate was respectively added inthe lead solution (1000mL 10mgL) and cadmium solution(1000mL 10mgL) The saturated adsorption of metal ionson cross-linked starch xanthate was 50mgg The polymer-metal complex was removed by filtration after static adsorp-tion for 4 hours and the filtrate was used for the residual

Dosage of potassium persulfate (mg)140120100806040

48

46

44

42

40

38

36

34

Abso

rben

cy (m

gg)

Pb2+

Cd2+

Figure 1 Effect of potassium persulfate amount on Pb2+and Cd2+adsorption capacity

metal analysis The adsorption capacity was calculated fromthe following expressions [11 12]

119876 =(1198620 times 1198810 minus 1198621 times 1198811)

119898 (1)

In this formula 119876 (mmolg) is the adsorption capacityof the adsorbent and 1198620 and 1198621 (moles per liter) are theinitial and final concentrations of Pb2+ and Cd2+ ions in theadsorption solution Respectively 1198810 and 1198811 (milliliters) arethe initial and final volume of Pb2+ and Cd2+ ions in theadsorption solution and 119898 (grams) is the dose of the cross-linked starch xanthate

3 Results and Discussions

The cross-linked starch xanthate that was prepared underthe different synthesis conditions would be expected to havedifferent absorbency for the metal ions So the effects ofdifferent synthesis conditions on the absorbency of the cross-linked starch xanthate were investigated

31 Effect of Dosage of the Initiator Potassium PersulfateThe effect of dosage of the initiator potassium persulfatewas investigated by changing the dosage of the initiatorpotassium persulfate under the conditions that the starchquality and other factors were constant to study its effect onthe adsorption amount of metal ions As shown in Figure 1the trends of absorbing Pb2+ and Cd2+ were similar It canbe seen that the absorbency increased totally with the dosageof K2S2O8 increasing When the amount of K2S2O8 washigher than the optimumpoint the change of the absorbencydecreasedThe maximal absorbencies of Pb2+ and Cd2+ were4711mgg and 3655mgg when the dosages of potassiumpersulfate were 70mg and 80mg respectively The cause

International Journal of Polymer Science 3

Potato starch xanthate and monomer ratio

1 14

1 13

1 12

1 11

1 10

1 9

1 8

1 7

1 6

1 5

1 4

4847464544434241403938373635343332

Abso

rben

cy (m

gg)

Pb2+

Cd2+

Figure 2 Effect of starch xanthate and monomer ratio on polymeradsorbed Pb2+ and Cd2+

was related to the relationship between average chain lengthand concentration of the initiator in the copolymerization[13] More graft copolymerization occurred between themonomers and the starch xanthate leading to the formationof more stable network structures which was helpful forthe increase of the absorbency On the one hand when theconcentration of the initiator was too high there would bea strong reaction with the starch molecules resulting in thedecrease of the main chain length [14 15] On the otherhand with the increase of K2S2O8 the copolymerization ratebecame so fast that the polymeric heat could not transfer intime leaded to the higher temperature of the system andenhanced the chance of chain transfer and chain cessationConsequently the absorbency of the polymer decreased [16]

32 Effect of Mass of Starch Xanthate and Monomer RatioThe effect of the weight ratio of starch xanthate to monomers(ranging from 1 5 to 1 14) on the absorbency was investi-gated As shown in Figure 2 the trends of absorbing Pb2+and Cd2+ were also similar The absorbency increased withthe ratio of matrix to monomers increasing and reached amaximum then it slowly decreased with increasing of theamount of monomers The maximal adsorption amount ofPb2+ was 4702mgg when the weight ratio of starch xanthateto monomers reached 1 12 the absorbency of Cd2+ was3633mgg when the ratio reached 1 11 It can be explainedas follows on the one hand as the weight ratio of matrixto monomers increased more and more functional groupssuch as -COONa -CONH2 and -CONH were grafted ontothe starch xanthate these groups enhanced the capacity ofthe cross-linked starch xanthate chelated with metal ionsand the chemical adsorption improved On the other handthe grafted rate increased and the branch chain grafted instarch became long which was conducive to the formationof the ideal network structure and the grafted products

16141210864

Dosage of cross-linker (mg)

48

46

44

42

40

38

36

34

32

Abso

rben

cy (m

gg)

Pb2+

Cd2+

Figure 3 Dosage of cross-linker on polymer adsorbed Pb2+ andCd2+

formed appropriate holes so that the physical adsorptionimproved The acrylic acidrsquos self-polymerization enhancedwith the monomers increased Although the polyacrylic acidhas a mass of carboxyls these carboxyls were packagedinside the polyacrylic acid and hard to chelate with metalions Meanwhile the compactness of the cross-linked starchxanthate increased so that the polymeric network becamecloser [17] and thus the absorbency decreased

33 Effect of Dosage of Cross-Linker The effect of the amountof NN1015840-methylenebisacrylamide which was used as thecross-linker in the copolymerization was studied and theresult was shown in Figure 3 When the amount of cross-linker was lower than 12 and 13mg the absorbency of Pb2+and Cd2+ was increased with the amount of cross-linkerrising However it began to decrease when it was higherthan 12 and 13mg Therefore the maximal absorbency ofPb2+ and Cd2+ was up to 4695mgg and 3605mgg whenthe dosage of cross-linker was 12 and 13mg respectivelyAccording to Floryrsquos theory increasing cross-linker additioncould increase the number of nodes of the network andthe cross-linker density which was favorable to the cross-linked starch xanthate absorbing Low concentration of thecross-linker led to low degree of cross-linking and it washard for network structure to form so the absorbency ofmetal ions was low However when it was higher than thebest value there were more cross-linking points and thepores became smaller in the network which caused themacroscopic decrease of the absorbency [18]

34 Effect of Solution pH The pH of aqueous solution isan important controlling parameter in the heavy metal ionsadsorption process [19 20] The cross-linked starch xanthatesamples were put into the Pb2+ and Cd2+ solutions overa pH range of 2ndash9 at room temperature to investigate theinfluence of pH on Pb2+ and Cd2+ ions adsorption property


Pb2+

Cd2+

pH

Abso

rben

cy (m

gg)

10987654321

50

40

30

20

10

0

Figure 4 Effect of solution pH on adsorbed Pb2+ and Cd2+

Figure 4 shows the effect of pH values on the Pb2+ and Cd2+ions adsorption properties of the adsorbents It is observedthat the adsorption capacity of cross-linked starch xanthateis pH dependent and shows a weak adsorption capacity atlow pH values The adsorption capacity is increased withincreasing pH values and the maximum capacity (47mggand 3612mgg) is achieved around pHof 50The effect of pHvalue on the removal of Pb2+ and Cd2+ ions can be explainedby the surface charge of the adsorbents in acidic and basicmedium [21] On the one hand in acidic medium the pHvalue is very low and the competitive capacity of H+ is muchstronger than metal ionrsquos On the other hand it may also bebecause H+ can react with active groups and the electrostaticrepulsion increases between active groups and metal ionsThen the coordination process between active groups andmetal ions is blocked [22] The S on the cross-linked starchxanthate prefer to chelate with hydrogen ions rather thanPb2+ and Cd2+ ions due to the protonation as shown in

Starch-O-CSSminus +HCl 997888rarr Starch-O-CSSminusH+ + Clminus (2)

Therefore the cross-linked starch xanthate displays the posi-tive surface charge In basic medium the cross-linked starchxanthate has the negative surface charge due to the attractionbetween the base and theH+Thus the adsorption ability wasenhanced significantly with increasing pH values due to theelectrostatic attraction

35 Effect of the Initial Concentration of Pb2+ and Cd2+ Theeffects of the initial concentration of Pb2+ and Cd2+ werestudied and the result was shown in Figure 5The absorbencyincreased with the increasing concentration of metal ionsand the tendency of absorbency became slow It can beexplained as follows when the concentrations of metal ionswere low the amounts of metal ions were far lower than thesaturated adsorption capacity of cross-linked starch xanthateThe polymeric absorbent has many vacant sites so theconcentration gradient took place in the solution that it can

Pb2+

Cd2+

The initial concentration of Pb2+ and Cd2+ (mgL)

800

700

600

500

400

300

200

100

0

Abso

rben

cy (m

gg)

300250200150100500

Figure 5 Effect of the initial concentration on absorbed Pb2+ andCd2+

constantly absorb Pb2+ and Cd2+ The adsorption capacityincreased rapidly with the increasing of concentration Thevacant sitewas constantly filledwith increasing concentrationofmetal ions and the concentration gradient decreasedwhichresulted in the slower tendency of absorbency [23 24] andfinally there was a balance that was achieved

36 FTIR Spectra The various spectral bands along withrespective frequencies of the native starch starch xanthateand cross-linked starch xanthate are shown in their spectraaccording to Figure 6 Native starch spectra showed thatthe 3443 cmminus1 was the stretch vibration adsorption band ofthe hydroxyl Other adsorption bands appeared at 2927 cmminus1as a result of methylene stretching vibrations The adsorp-tion band of 1639 cmminus1 comes from the hydroxyl flexuralvibration The starch xanthatersquos intensity of the -OH banddecreased and the peak became narrower compared withnative starch because the hydroxyl took part in the processof the synthesis of starch xanthate 1204 cmminus1 was C=S andC-S band stretching of starch xanthate The spectra provethat the starch reacted with carbon disulfide under alkalineconditions and generated starch xanthateThe reasonwhy theadsorption peak becomes wider and the intensity increasesat 1640 and 1620 cmminus1 was the stretch vibration of C=O in-CONH2 and the symmetrical and asymmetrical stretchingvibration of -COONa and -COONH4 It indicated that thestarch xanthate had graft copolymerization reaction with theacrylamide and sodium acrylate as expected

37 X-Ray Diffraction Figure 7 shows the X-ray diffrac-tograms of native starch starch xanthate and cross-linkedstarch xanthate The sharp peaks diffraction is the crys-talline region of native starch and the dispersion diffractionalso represents the amorphous region of native starch Thediffraction pattern of native starch shows several sharppeaks at 15ndash25∘ indicating the crystalline structure of native


5001000150020002500300035004000

344351

16401620

1204

1400163929

minus80

minus60minus40minus20

020406080100

T

Native starch

Starch xanthate

Cross-linked starchxanthate

(a)

(b)

(c)

Figure 6 IR spectrum of starch starch xanthate and cross-linked starch xanthate

Table 1 Quantitative data of EDX measurement for cross-linked starch xanthate adsorbed Pb2+

ElAN series unn 119862 norm [wt] 119862 Atom [wt] 119862 Error (1 Sigma) [at] 119870 fact 119885 corr [wt] 119860 corr 119865 corrC 6 K-series 6372 6372 7047 1168 0865 0737 1000 1000O 8 K-series 2691 2691 2235 830 0186 1448 1000 1000N 7 K-series 745 745 706 553 0054 1391 1000 1000Pb 48 L-series 192 192 012 007 0110 3641 1000 1133

Table 2 Quantitative data of EDX measurement for cross-linked starch xanthate after adsorbed Cd2+

ElAN series unn 119862 norm [wt] 119862 Atom [wt] 119862 error (1 Sigma) [at] 119870 fact 119885 corr [wt] 119860 corr 119865 corrC 6 K-series 6605 6605 7174 1258 0872 0757 1000 1000O 8 K-series 2807 2807 2289 922 0190 1475 1000 1000N 7 K-series 575 575 536 539 0040 1435 1000 1000Cd 48 L-series 013 013 001 007 0001 2443 1000 1275

0 10 20 30 40 50 60 70 80

Inte

nsity

(au

)

2theta (deg)

(a)

(b)

(c)

Figure 7 The X-ray diffractogram of native starch (a) starchxanthate (b) and cross-liked starch xanthate (c)

starch [25ndash27] The crystalline structure of native starchwas destroyed on account of the chemical cross-linking andphysical cross-linking when synthesizing the cross-linkedstarch xanthate The cross-linked network also prevented thecrystallization capacity of starch xanthate so the diffractedintensity becomes weaker

38 Scanning Electron Microscopy The scanning electronmicroscope images of native starch starch xanthate and

cross-linked starch xanthate that absorbed Pb2+ and Cd2+were shown in Figure 8The native starch granules are oval inshape with smooth surface The starch xanthate has a coarsesurface rather than a smooth surface with loose structurebecause of the chemical reaction that happened on the surface[28 29] Figures 8(c) and 8(d) indicate that the surface ofcross-linked starch xanthate covers a large number of whitespots with irregular shapesThat is because the space networkstructure is completely braced after it absorbed Pb2+ andCd2+ And when the gel was dried though each networkstructure on the cross-linked starch xanthate surface returnsto its close state before water adsorption the stains remain tobe seenThese irregularly shaped white spots explain that thecopolymerization and cross-linkingmay have some degree ofheterogeneity [30]

39 Energy Dispersive X-Ray Spectroscopy Figures 9 and 10show that the corresponding characteristic peak appearedon the Energy Dispersive X-Ray Spectroscopy graphs afterthe adsorption of Pb2+ and Cd2+ by the cross-linked starchxanthate It can be seen in Tables 1 and 2 that the cross-linked starch xanthate absorbed Pb2+ and Cd2+ successfullyand the absorbency of Pb2+ was higher compared to Cd2+The reasons were various Firstly different chelate ability ledto the difference of absorbency The chelate ability of Pb2+ isbetter compared to Cd2+ Secondly the different adsorptiondominant mechanisms lead to the difference of absorbency[3 31]


(a) Native starch (b) Starch xanthate

(c) Polymer with adsorbed Pb2+ (d) Polymer with adsorbed Cd2+

Figure 8 Scanning electron micrographs

2 4 6 8 10 12 14 16 18 20(keV)

(cps

eV

)

CO

N

PbPb

00

05

10

15

20

25

30

Figure 9 EDX measurement of cross-linked starch xanthate thatabsorbed Pb2+

4 Adsorption Isotherms

The analysis of the isotherm data is an important way toaccurately represent the relationship between adsorbent andadsorbate [32] A typical adsorption isotherm for Pb2+ andCd2+ is presented in Figures 11 and 12 In this paper theisotherms of Pb2+ and Cd2+ adsorption on the cross-linkedstarch xanthate were studied by calculating adsorption capac-ity as a function of Pb2+ and Cd2+ equilibrium concentrationThe analysis of obtained experimental data is based on theLangmuir and Freundlich isotherm models The Langmuirmodel assumes a homogeneous surface with respect to theenergy of adsorption inwhichno interaction existed betweenadsorbed species and all the adsorption sites are equally

2 4 6 8 10 12 14 16 18 20(keV)

00020406081012

(cps

eV

)

CO

N

Cd

Cd

Figure 10 EDX measurement of cross-linked starch xanthate thatabsorbed Cd2+

available to the adsorbed specie [33] Langmuir adsorptionmodel can be described as

119862119890119902119890=1

119896119890119902119898+119862119890119902119898 (3)

In this formula 119902119890 is the absorbed amount of the Pb2+ andCd2+ at equilibrium (mgg)119862119890 is the adsorbate concentrationat equilibrium in aqueous solution (mgL) 119870119890 (Lmg) isthe Langmuir adsorption constant related to the energyof adsorption and 119902119898 (mgg) is the maximum monolayeradsorption capacity


45

40

35

30

2 3 4 5 6 7

50

55

60

65

70

Pb2+

Cd2+

lnqe

lnCe

Figure 11 Freundlich isotherm curve fitting of Pb2+ and Cd2+adsorption for cross-linked starch xanthate

Table 3 Isotherms constants and correlation coefficients for theadsorption of Pb2+ and Cd2+ on cross-linked starch xanthate

Langmuir equation Freundlich equation

119870119890Pb2+ 7950

119899Pb2+ 2236

Cd2+ 3576 Cd2+ 1857

1198772Pb2+ 0969

1198772Pb2+ 0998

Cd2+ 0977 Cd2+ 0994

119902119898Pb2+ 50mgg

119870119891Pb2+ 0586

Cd2+ 50mgg Cd2+ 0527

Freundlich isothermmodel can be applied to the nonidealadsorption on heterogeneous surfaces as well as multilayeradsorption [34] and it is described as [35]

ln 119902119890 = ln119870119891 +1

119899ln119862119890 (4)

In this formula 119902119890 is the equilibrium solute concentrationon adsorbent (mgg) 119862119890 is the equilibrium concentrationof the solute (mgL) 119870119891 (mgg) is the Freundlich constantbeing indicative of the extent of adsorption and ldquo119899rdquo is theheterogeneity factor as an indicator of adsorption effective-ness The parameters for these two isotherms are calculatedThe results indicate that the correlation coefficient values ofFreundlich isotherm (Pb2+ 1198772 = 0998 Cd2+ 1198772 = 0994)were higher than those of the Langmuir isotherm (Pb2+ 1198772= 0969 Cd2+ 1198772 = 0977) which implies that the Freundlichmodel is better fitted to the experimental data than Langmuirmodel The adsorption characteristics of Pb2+ and Cd2+were multilayer adsorption [36 37] Isotherms constants andcorrelation coefficients for the adsorption of Pb2+ and Cd2+on cross-linked starch xanthate were shown in Table 3

Ce

qeC

e

8

7

6

5

4

3

454035302520151050

Pb2+

Cd2+

Figure 12 Langmuir isotherm curve fitting of Pb2+ and Cd2+adsorption for cross-linked starch xanthate

5 Conclusion

A cross-linked starch xanthate was prepared by graft copoly-merization of acrylamide and sodium acrylate onto starchxanthate using potassium persulfate and sodium hydrogensulfite initiating system andNN1015840-methylenebisacrylamide asa cross-linkerThe adsorption capacity to Pb2+ and Cd2+ ionsof the polymer synthesis under different conditions was stud-iedThe highest quantities of Pb2+ and Cd2+ adsorption were4711mgg and 3655mgg respectively Freundlich model isbetter fitted to the experimental data than Langmuir model

Competing Interests

The authors declare that they have no competing interests

References

[1] L Guo S-F Zhang B-Z Ju J-Z Yang and X Quan ldquoRemovalof Pb(II) from aqueous solution by cross-linked starch phos-phate carbamaterdquo Journal of Polymer Research vol 13 no 3 pp213ndash217 2006

[2] Z Li J Chen H Guo et al ldquoTriboelectrification-enabledself-powered detection and removal of heavy metal ions inwastewaterrdquo Advanced Materials vol 28 no 15 pp 2983ndash29912016

[3] B XiangW Fan X Yi et al ldquoDithiocarbamate-modified starchderivatives with high heavy metal adsorption performancerdquoCarbohydrate Polymers vol 136 pp 30ndash37 2016

[4] G R Mahdavinia S Hasanpour L Behrouzi and HSheykhloie ldquoStudy on adsorption of Cu(II) onmagnetic starch-g-polyamidoximemontmorilloniteFe3O4 nanocomposites asnovel chelating ligandsrdquo StarchmdashStarke vol 68 no 3-4 pp188ndash199 2016

[5] D Soto J Urdaneta K Pernıa O Leon A Munoz-Bonilla andM Fernandez-Garcıa ldquoRemoval of heavy metal ions in waterby starch estersrdquo StarchStaerke vol 68 no 1-2 pp 37ndash46 2016


[6] D-K Kweon J-K Choi E-K Kim and S-T Lim ldquoAdsorptionof divalent metal ions by succinylated and oxidized cornstarchesrdquo Carbohydrate Polymers vol 46 no 2 pp 171ndash1772001

[7] S-M Xu S Feng G Peng J-D Wang and A YushanldquoRemoval of Pb (II) by crosslinked amphoteric starch contain-ing the carboxymethyl grouprdquo Carbohydrate Polymers vol 60no 3 pp 301ndash305 2005

[8] S R Popuri R Frederick C-Y Chang S-S Fang C-CWangand L-C Lee ldquoRemoval of copper (II) ions from aqueoussolutions onto chitosancarbon nanotubes composite sorbentrdquoDesalination and Water Treatment vol 52 no 4-6 pp 691ndash7012014

[9] X X Zou ldquoA study of SGPAC type chelating agent for adsorp-tion of heavy metal ionsrdquo Ion Exchange and Adsorption vol 7pp 15ndash20 1991

[10] T Lv Z Tian and C Hu ldquoSynthesis of a new chelating cornstarch and application on preconcentration of copper (II)rdquoAdvanced Materials Research vol 113-116 pp 956ndash959 2010

[11] Y Bulut G Akcay D Elma and I E Serhatli ldquoSynthesis of clay-based superabsorbent composite and its sorption capabilityrdquoJournal of Hazardous Materials vol 171 no 1ndash3 pp 717ndash7232009

[12] S S Yilmaz D Kul M Erdol M Ozdemir and R AbbasogluldquoSynthesis of a novel crosslinked superabsorbent copolymerwith diazacyclooctadecane crown ether and its sorption capa-bilityrdquo European Polymer Journal vol 43 no 5 pp 1923ndash19322007

[13] J Zhang Q Wang and A Wang ldquoSynthesis and charac-terization of chitosan-g-poly(acrylic acid)attapulgite superab-sorbent compositesrdquo Carbohydrate Polymers vol 68 no 2 pp367ndash374 2007

[14] Z Ma Q Li Q Yue B Gao X Xu and Q Zhong ldquoSynthesisand characterization of a novel super-absorbent based on wheatstrawrdquo Bioresource Technology vol 102 no 3 pp 2853ndash28582007

[15] G B Marandi S Hariri and G R Mahdavinia ldquoEffect ofhydrophobicmonomer on the synthesis and swelling behaviourof a collagen-graft-poly[(acrylic acid)-co-(sodium acrylate)]hydrogelrdquo Polymer International vol 58 no 2 pp 227ndash2352009

[16] J Liu Q Li Y Su Q Yue B Gao and R Wang ldquoSynthesis ofwheat straw cellulose-g-poly (potassium acrylate)PVA semi-IPNs superabsorbent resinrdquo Carbohydrate Polymers vol 94 no1 pp 539ndash546 2013

[17] Z Liu Y Miao ZWang and G Yin ldquoSynthesis and characteri-zation of a novel super-absorbent based on chemicallymodifiedpulverized wheat straw and acrylic acidrdquo Carbohydrate Poly-mers vol 77 no 1 pp 131ndash135 2009

[18] A Pourjavadi S Barzegar and G R Mahdavinia ldquoMBA-crosslinked Na-AlgCMC as a smart full-polysaccharide super-absorbent hydrogelsrdquo Carbohydrate Polymers vol 66 no 3 pp386ndash395 2006

[19] M Irani H Ismail Z Ahmad and M Fan ldquoSynthe-sis of linear low-density polyethylene-g-poly (acrylic acid)-co-starchorgano-montmorillonite hydrogel composite as anadsorbent for removal of Pb(ΙΙ) from aqueous solutionsrdquoJournal of Environmental Sciences vol 27 pp 9ndash20 2015

[20] K Lappalainen J Karkkainen A Rusanen et al ldquoBinding ofsome heavy metal ions in aqueous solution with cationized orsulphonylated starch or waste starchrdquo Starch - Starke vol 68no 9-10 pp 900ndash908 2016

[21] F Fu and Q Wang ldquoRemoval of heavy metal ions fromwastewaters a reviewrdquo Journal of Environmental Managementvol 92 no 3 pp 407ndash418 2011

[22] M Al-Shannag Z Al-Qodah K Bani-MelhemM R Qtaishatand M Alkasrawi ldquoHeavy metal ions removal from metalplating wastewater using electrocoagulation kinetic study andprocess performancerdquo Chemical Engineering Journal vol 260pp 749ndash756 2015

[23] Z Chen M Liu and S Ma ldquoSynthesis andmodification of salt-resistant superabsorbent polymersrdquo Reactive and FunctionalPolymers vol 62 no 1 pp 85ndash92 2005

[24] Y Zheng and A Wang ldquoStudy on superabsorbent com-posites XVIII Preparation characterization and propertyevaluation of poly(acrylic acid-co-acrylamide)organomont-morillonitesodium humate superabsorbent compositesrdquo Jour-nal of Applied Polymer Science vol 108 no 1 pp 211ndash219 2008

[25] H Chi K Xu X Wu et al ldquoEffect of acetylation on theproperties of corn starchrdquo Food Chemistry vol 106 no 3 pp923ndash928 2008

[26] A K Meena G K Mishra P K Rai C Rajagopal and P NNagar ldquoRemoval of heavy metal ions from aqueous solutionsusing carbon aerogel as an adsorbentrdquo Journal of HazardousMaterials vol 122 no 1-2 pp 161ndash170 2005

[27] S Garg and A K Jana ldquoEffect of propylation of starchwith different degrees of substitution on the properties andcharacteristics of starch-low density polyethylene blend filmsrdquoJournal of Applied Polymer Science vol 122 no 4 pp 2197ndash22082011

[28] M A Bhat H Chisti and S A Shah ldquoRemoval of heavy metalions from water by cross-linked potato di-starch phosphatepolymerrdquo Separation Science and Technology vol 50 no 12 pp1741ndash1747 2015

[29] GHWenDWang andN Shan ldquoOn the absorption behaviorsof the super xanthate starch resin for heavy metal ionsrdquo Journalof Safety and Environment vol 15 pp 221ndash227 2015

[30] E S Abdel-Halim and S S Al-Deyab ldquoPreparation ofpoly(acrylic acid)starch hydrogel and its application for cad-mium ion removal from aqueous solutionsrdquo Reactive andFunctional Polymers vol 75 pp 1ndash8 2014

[31] N H Baharuddin N M N Sulaiman and M K AroualdquoRemoval of zinc and lead ions by polymer-enhanced ultra-filtration using unmodified starch as novel binding polymerrdquoInternational Journal of Environmental Science and Technologyvol 12 no 6 pp 1825ndash1834 2015

[32] D Soto J Urdaneta K Pernıa O Leon A Munoz-Bonillaand M Fernandez-Garcıa ldquoHeavy metal (Cd2+ Ni2+ Pb2+ andNi2+) adsorption in aqueous solutions by oxidized starchesrdquoPolymers for Advanced Technologies vol 26 no 2 pp 147ndash1522015

[33] K K H Choy J F Porter and G McKay ldquoLangmuir isothermmodels applied to the multicomponent sorption of acid dyesfrom effluent onto activated carbonrdquo Journal of Chemical andEngineering Data vol 45 no 4 pp 575ndash584 2000

[34] X-S Wang and Y Qin ldquoEquilibrium sorption isotherms for ofCu2+ on rice branrdquo Process Biochemistry vol 40 no 2 pp 677ndash680 2005

[35] G R Mahdavinia A Massoudi A Baghban and B MassoumildquoNovel carrageenan-based hydrogel nanocomposites contain-ing laponite RD and their application to remove cationic dyerdquoIranian Polymer Journal (English Edition) vol 21 no 9 pp 609ndash619 2012


[36] D Kohli S Garg and A K Jana ldquoSynthesis of cross-linkedstarch based polymers for sorption of organic pollutants fromaqueous solutionsrdquo Indian Chemical Engineer vol 54 no 3 pp210ndash222 2012

[37] X Jiang Y Liu andM Gu ldquoAbsorption of sulphur dioxide withsodium citrate buffer solution in a rotating packed bedrdquoChineseJournal of Chemical Engineering vol 19 no 4 pp 687ndash692 2011

Submit your manuscripts athttpswwwhindawicom

ScientificaHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CorrosionInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Polymer ScienceInternational Journal of



CeramicsJournal of


CompositesJournal of

NanoparticlesJournal of



International Journal of

Biomaterials


NanoscienceJournal of

TextilesHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Journal of

NanotechnologyHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

CrystallographyJournal of


The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014


CoatingsJournal of

Advances in

Materials Science and EngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Smart Materials Research



MetallurgyJournal of


BioMed Research International

MaterialsJournal of


Nano

materials


Journal ofNanomaterials


In this study we describe the use of cross-linked starchxanthate as a complexing agent that can absorb Pb2+ andCd2+ through grafted copolymerization with acrylamide andsodium acrylate and focus on its adsorption properties andits potential for recycling the heavy metal ions

2 Experimental Section

21 Materials Potato starch food grade was purchased fromInner Mongolia Ke Xinyuan Co Ltd China The sodiumhydroxide was obtained from Tianjin North Fine ChemicalsCo Ltd China Carbon disulfide was purchased fromChineseMedicine Group Chemical Reagent Co Ltd ChinaAbsolute ethanol was purchased from Tianjin North FineChemicals Co Ltd China Acrylic acid was purchased fromChineseMedicine Group Chemical Reagent Co Ltd ChinaAcrylamide was obtained from Chinese Medicine GroupChemical Reagent Co Ltd China Potassium persulfatewas purchased from Chinese Medicine Group ChemicalReagent Co Ltd China The sodium bisulfite was obtainedfrom Tianjin North Fine Chemicals Co Ltd China NN1015840-Methylenebisacrylamide was purchased from Beijing Chem-ical Reagent Company Co Ltd China All the aboveingredients except potato starch were of analytical grades

22 Preparation of Starch Xanthate 50 g native starch wasdispersed in 25mL of distilled water and the concentration of14 sodium hydroxide solution was added to the resultingslurry in room temperature Then 35mL carbon disulfidewas added to the system To control the reaction temperaturethe reactor was placed in a water bath preset at 30∘C for 2 h

The reaction product was precipitated in an excess ofethanol and separated by filtration Then we dried it in avacuum oven at 40∘C for two days Moreover the desiredstarch xanthatewasmilled and sifted through a 60-mesh sieveto prepare samples

23 Synthesis of Cross-Linked Starch Xanthate 25 g starchxanthate was dispersed in 50mL of distilled water and stirredfor a period of time then 40mL sodium acrylate and aselected amount of acrylamide were poured into the solutionfollowed by potassium persulfate (20mgmL) and a selectedamount of NN1015840-methylenebisacrylamide They were reactedunder a nitrogen gas atmosphere by heating the solution asto make graft copolymerization reaction occur The productwas dried for 12 h and finally ground to powder

24Metal Adsorption and Procedure forQuantitative AnalysisAqueous solutions of Pb2+ (Pb 10mgL) and Cd2+ (Cd10mgL) ions were prepared by dissolving 07993 g Pb(NO3)2and 06861 g Cd(NO3)2sdot4H2O in 500mL deionized water02 g cross-linked starch xanthate was respectively added inthe lead solution (1000mL 10mgL) and cadmium solution(1000mL 10mgL) The saturated adsorption of metal ionson cross-linked starch xanthate was 50mgg The polymer-metal complex was removed by filtration after static adsorp-tion for 4 hours and the filtrate was used for the residual

Dosage of potassium persulfate (mg)140120100806040

48

46

44

42

40

38

36

34

Abso

rben

cy (m

gg)

Pb2+

Cd2+

Figure 1 Effect of potassium persulfate amount on Pb2+and Cd2+adsorption capacity

metal analysis The adsorption capacity was calculated fromthe following expressions [11 12]

119876 =(1198620 times 1198810 minus 1198621 times 1198811)

119898 (1)

In this formula 119876 (mmolg) is the adsorption capacityof the adsorbent and 1198620 and 1198621 (moles per liter) are theinitial and final concentrations of Pb2+ and Cd2+ ions in theadsorption solution Respectively 1198810 and 1198811 (milliliters) arethe initial and final volume of Pb2+ and Cd2+ ions in theadsorption solution and 119898 (grams) is the dose of the cross-linked starch xanthate

3 Results and Discussions

The cross-linked starch xanthate that was prepared underthe different synthesis conditions would be expected to havedifferent absorbency for the metal ions So the effects ofdifferent synthesis conditions on the absorbency of the cross-linked starch xanthate were investigated

31 Effect of Dosage of the Initiator Potassium PersulfateThe effect of dosage of the initiator potassium persulfatewas investigated by changing the dosage of the initiatorpotassium persulfate under the conditions that the starchquality and other factors were constant to study its effect onthe adsorption amount of metal ions As shown in Figure 1the trends of absorbing Pb2+ and Cd2+ were similar It canbe seen that the absorbency increased totally with the dosageof K2S2O8 increasing When the amount of K2S2O8 washigher than the optimumpoint the change of the absorbencydecreasedThe maximal absorbencies of Pb2+ and Cd2+ were4711mgg and 3655mgg when the dosages of potassiumpersulfate were 70mg and 80mg respectively The cause



1 14

1 13

1 12

1 11

1 10

1 9

1 8

1 7

1 6

1 5

1 4

4847464544434241403938373635343332

Abso

rben

cy (m

gg)

Pb2+

Cd2+




16141210864


48

46

44

42

40

38

36

34

32

Abso

rben

cy (m

gg)

Pb2+

Cd2+






Pb2+

Cd2+

pH

Abso

rben

cy (m

gg)

10987654321

50

40

30

20

10

0






Pb2+

Cd2+


800

700

600

500

400

300

200

100

0

Abso

rben

cy (m

gg)

300250200150100500






5001000150020002500300035004000

344351

16401620

1204

1400163929

minus80


020406080100

T

Native starch

Starch xanthate


(a)

(b)

(c)






0 10 20 30 40 50 60 70 80

Inte

nsity

(au

)

2theta (deg)

(a)

(b)

(c)










2 4 6 8 10 12 14 16 18 20(keV)

(cps

eV

)

CO

N

PbPb

00

05

10

15

20

25

30




2 4 6 8 10 12 14 16 18 20(keV)

00020406081012

(cps

eV

)

CO

N

Cd

Cd



119862119890119902119890=1

119896119890119902119898+119862119890119902119898 (3)



45

40

35

30

2 3 4 5 6 7

50

55

60

65

70

Pb2+

Cd2+

lnqe

lnCe




119870119890Pb2+ 7950

119899Pb2+ 2236

Cd2+ 3576 Cd2+ 1857

1198772Pb2+ 0969

1198772Pb2+ 0998

Cd2+ 0977 Cd2+ 0994

119902119898Pb2+ 50mgg

119870119891Pb2+ 0586

Cd2+ 50mgg Cd2+ 0527


ln 119902119890 = ln119870119891 +1

119899ln119862119890 (4)


Ce

qeC

e

8

7

6

5

4

3

454035302520151050

Pb2+

Cd2+


5 Conclusion


Competing Interests


References















































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials





1 14

1 13

1 12

1 11

1 10

1 9

1 8

1 7

1 6

1 5

1 4

4847464544434241403938373635343332

Abso

rben

cy (m

gg)

Pb2+

Cd2+




16141210864


48

46

44

42

40

38

36

34

32

Abso

rben

cy (m

gg)

Pb2+

Cd2+






Pb2+

Cd2+

pH

Abso

rben

cy (m

gg)

10987654321

50

40

30

20

10

0






Pb2+

Cd2+


800

700

600

500

400

300

200

100

0

Abso

rben

cy (m

gg)

300250200150100500






5001000150020002500300035004000

344351

16401620

1204

1400163929

minus80


020406080100

T

Native starch

Starch xanthate


(a)

(b)

(c)






0 10 20 30 40 50 60 70 80

Inte

nsity

(au

)

2theta (deg)

(a)

(b)

(c)










2 4 6 8 10 12 14 16 18 20(keV)

(cps

eV

)

CO

N

PbPb

00

05

10

15

20

25

30




2 4 6 8 10 12 14 16 18 20(keV)

00020406081012

(cps

eV

)

CO

N

Cd

Cd



119862119890119902119890=1

119896119890119902119898+119862119890119902119898 (3)



45

40

35

30

2 3 4 5 6 7

50

55

60

65

70

Pb2+

Cd2+

lnqe

lnCe




119870119890Pb2+ 7950

119899Pb2+ 2236

Cd2+ 3576 Cd2+ 1857

1198772Pb2+ 0969

1198772Pb2+ 0998

Cd2+ 0977 Cd2+ 0994

119902119898Pb2+ 50mgg

119870119891Pb2+ 0586

Cd2+ 50mgg Cd2+ 0527


ln 119902119890 = ln119870119891 +1

119899ln119862119890 (4)


Ce

qeC

e

8

7

6

5

4

3

454035302520151050

Pb2+

Cd2+


5 Conclusion


Competing Interests


References















































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




Pb2+

Cd2+

pH

Abso

rben

cy (m

gg)

10987654321

50

40

30

20

10

0






Pb2+

Cd2+


800

700

600

500

400

300

200

100

0

Abso

rben

cy (m

gg)

300250200150100500






5001000150020002500300035004000

344351

16401620

1204

1400163929

minus80


020406080100

T

Native starch

Starch xanthate


(a)

(b)

(c)






0 10 20 30 40 50 60 70 80

Inte

nsity

(au

)

2theta (deg)

(a)

(b)

(c)










2 4 6 8 10 12 14 16 18 20(keV)

(cps

eV

)

CO

N

PbPb

00

05

10

15

20

25

30




2 4 6 8 10 12 14 16 18 20(keV)

00020406081012

(cps

eV

)

CO

N

Cd

Cd



119862119890119902119890=1

119896119890119902119898+119862119890119902119898 (3)



45

40

35

30

2 3 4 5 6 7

50

55

60

65

70

Pb2+

Cd2+

lnqe

lnCe




119870119890Pb2+ 7950

119899Pb2+ 2236

Cd2+ 3576 Cd2+ 1857

1198772Pb2+ 0969

1198772Pb2+ 0998

Cd2+ 0977 Cd2+ 0994

119902119898Pb2+ 50mgg

119870119891Pb2+ 0586

Cd2+ 50mgg Cd2+ 0527


ln 119902119890 = ln119870119891 +1

119899ln119862119890 (4)


Ce

qeC

e

8

7

6

5

4

3

454035302520151050

Pb2+

Cd2+


5 Conclusion


Competing Interests


References















































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




5001000150020002500300035004000

344351

16401620

1204

1400163929

minus80


020406080100

T

Native starch

Starch xanthate


(a)

(b)

(c)






0 10 20 30 40 50 60 70 80

Inte

nsity

(au

)

2theta (deg)

(a)

(b)

(c)










2 4 6 8 10 12 14 16 18 20(keV)

(cps

eV

)

CO

N

PbPb

00

05

10

15

20

25

30




2 4 6 8 10 12 14 16 18 20(keV)

00020406081012

(cps

eV

)

CO

N

Cd

Cd



119862119890119902119890=1

119896119890119902119898+119862119890119902119898 (3)



45

40

35

30

2 3 4 5 6 7

50

55

60

65

70

Pb2+

Cd2+

lnqe

lnCe




119870119890Pb2+ 7950

119899Pb2+ 2236

Cd2+ 3576 Cd2+ 1857

1198772Pb2+ 0969

1198772Pb2+ 0998

Cd2+ 0977 Cd2+ 0994

119902119898Pb2+ 50mgg

119870119891Pb2+ 0586

Cd2+ 50mgg Cd2+ 0527


ln 119902119890 = ln119870119891 +1

119899ln119862119890 (4)


Ce

qeC

e

8

7

6

5

4

3

454035302520151050

Pb2+

Cd2+


5 Conclusion


Competing Interests


References















































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials







2 4 6 8 10 12 14 16 18 20(keV)

(cps

eV

)

CO

N

PbPb

00

05

10

15

20

25

30




2 4 6 8 10 12 14 16 18 20(keV)

00020406081012

(cps

eV

)

CO

N

Cd

Cd



119862119890119902119890=1

119896119890119902119898+119862119890119902119898 (3)



45

40

35

30

2 3 4 5 6 7

50

55

60

65

70

Pb2+

Cd2+

lnqe

lnCe




119870119890Pb2+ 7950

119899Pb2+ 2236

Cd2+ 3576 Cd2+ 1857

1198772Pb2+ 0969

1198772Pb2+ 0998

Cd2+ 0977 Cd2+ 0994

119902119898Pb2+ 50mgg

119870119891Pb2+ 0586

Cd2+ 50mgg Cd2+ 0527


ln 119902119890 = ln119870119891 +1

119899ln119862119890 (4)


Ce

qeC

e

8

7

6

5

4

3

454035302520151050

Pb2+

Cd2+


5 Conclusion


Competing Interests


References















































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




45

40

35

30

2 3 4 5 6 7

50

55

60

65

70

Pb2+

Cd2+

lnqe

lnCe




119870119890Pb2+ 7950

119899Pb2+ 2236

Cd2+ 3576 Cd2+ 1857

1198772Pb2+ 0969

1198772Pb2+ 0998

Cd2+ 0977 Cd2+ 0994

119902119898Pb2+ 50mgg

119870119891Pb2+ 0586

Cd2+ 50mgg Cd2+ 0527


ln 119902119890 = ln119870119891 +1

119899ln119862119890 (4)


Ce

qeC

e

8

7

6

5

4

3

454035302520151050

Pb2+

Cd2+


5 Conclusion


Competing Interests


References















































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials












































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials



absorbed pb2+ and cd2+ ions in water by cross-linked...

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