Removal of Copper II Ions Aqueous Solution Onto

5/24/2018 Removal of Copper II Ions Aqueous Solution Onto

1/10

ELSEVIER Reactive Functional Polymers 50 (2002 ) 181- 190

RE TIVE&FUN TION LPOLYMERS

.elsevier.corn/ locate / react . l ~ C >

Removal of copper(II) ions fr T aqueous solution ontochitosan and cross-linked chitosan beadsW.s . Wan Ngah*, c.s. Endud, R. Mayanar

Schocl Chemical Sciences. Universiti Saills Malaysia 11800 Pulau Pinang MalaysiaReceived 10 March 2001: received in revised form 26 September 200 1: accepted 10 October 200 I

Ab stractThe adsorption of Cu(II J ions onto chitosan and cross-li nked chitosan beads has been investigated. Chitosan beads were

cross-linked with glutarald ehyde (GLA). epichlorohydrin (ECH) and ethylene glycol diglycidyl ether (EGDE) in order toobtain sorbents that are insoluble in aqueous acidic and basic soluti on. Batch adsorption experiments were carried out as afunction of pH, agitation period, agitation rate and concentratio n of Cut ll ) ions. A pH of 6.0 was found to be a optimum forCurll ) adsorption on chitosan and cross-linked chitosan beads. Isotherm studies indicate Cu(II) can be effectively removedby chitosan and cross-linked chitosan beads. Adsorption isothermal data could be well interpreted by the Langmuir equa tion.Langmuir constants have been determined for chitosan and cross- linked chitosan beads . The experimental data of theadsorption equil ibrium from Cu(II) solution correlated well with the Langmuir isotherm equation. The uptakes of Cu( II) ionson chitosan beads were 8C.71 mg Cul l/ g chitosan, on chitosan-GLA beads were 59.67 mg Cu(II) /g chitosan-GLA, onchitosan-ECH beads were 62.47 mg Cu(II)/ g chitosan-ECH and on chitosan-EGDE beads were 45.94 mg Cut ll ) ,'gchitosan-EGDE. The Cu(I1) ions can be removed from the chito san and cross-linked chito san beads rapidly by treatmentwith an aqueous EDTA so ution and at the same time the chitosan and cross-linked chitosan beads can be regenerated andalso 'can be used again to idsorb heavy metal ions. 2002 Elsevier Science B All rights reserved.Keywords: Chitosan beads; C 'oss-Iinked chitosan beads; Swelling; Adsorption isotherm; Capacity: Desorption

IntroductionThe presence of he, vy metals in the environment has been of grea t concern because of theirincreased disc harge, toxic nature and otheradverse effec ts on receiving waters. The po

tential sources of copper in industrial effluentsinclude metal cleaning and plating baths, pulp,paper and paper board mills. wood pulp pro-

Corresponding author.E mail address saime@u ;m.my (W.S. Wan Ngah).

duction , and the fertilizer industry, etc. l l lExcessive intake of copper results in an accumulation in the liver. It is also toxic to aquaticorganisms even at very small concentrations innatural water [I] .Various methods exist for the removal oftoxic metals from aqueous solution such as

ion-exchange, reverse osmosis, adsorption, complexation and precipitation [2 4]. Adsorption isthe most effective and widely used method.Activated carbon and chelation ion-exchangeresins have become increasingly popular com-

1381-5148 /02 / - see front n.atter 2002 Elsevier Science B All rights reserved.P lI : 51 3 81 -514 8(01 )001 3 -4


2/10

82 IVS. 11,// v3 11 et ul. / Reactive Functional Polymers 50 2002 181- 190

pared to other techniq ues. In spite of its widespread use in the water and waste industries,activated carbon and commercial chelating resins are still an expensive material and thereforethe production of low-cost alternatives has beenthe focus of researchers in the area.Biosorption or sorpt ion to material of bio

logical origin is recognized as an emergingtechnique for the treatment of was tewater containing heavy metals. Chitosan is a biopolymer ,whic h is of interes t to researchers concerningthe adsorption of metal ions on chitosan.Chitosan, also named poly([3-1-4)-2-amino-2deoxy-o-glucopyranose, a poly(o-glucosamin e)is prepared from chitin by deacetylating itsacetamido gro ups. Chitin or poly([3-1-4)-2-acetarnido-z-deoxy-c-glucopyranose is a naturalpolymer extrac ted from crustacean shells, suchas prawns , crabs, insect s and shrimps. Chitosanhas been descr ibed as a suita ble natural polymerfor the collection of metals ions [5-13 ], sincethe amine gro ups and hydroxyl gro ups on thechitosan chain can act as chelation sites formetal ions.Several methods have been used to modify

raw chitosan flake either physical [8,14] orchemical modifications [15 -1 9]. These modifications were proposed in order to improvepore size , mechanical strength, chemical stability. hydrophilicity and also biocompatibility.Acid environments produce the partia l dissolution of the polymer and to make the polymerinsoluble in acid ic medium, modificat ion byusing cross- linking agents used. Although crosslinking reduces the adsorption capacity but itenhance the resistance of chitosan against acid,alkali and chemical [15] . The cross-linkedchi tosan also are very stable and maintain theirstrength even in acidic and bas ic solutions [16].These charac teristics are very import an t for aadsorbent so that it can be used in a lower pHenvironment. Cross-linking also can change thecrystalline nature of chi tosan and enhance sorption abilities [17].The aim of this study was to compare the

adsorption behavio ur of chitosan and crosslinked chi tosan beads. The equilib ria of ad-

sorption of Cu(II) ion on these bead s fromwater were investigated. The influence of experimental conditions such as agitation period,agitation rate , pH and Cu(lI ) ions concentrationwill be studied. This information will be usefulfor further appli cation in the treatment of was teeffluents.

2. Experimental2. Chemical and reagentsChitosan was purchased from Fluka as a

flaked material, with a deacetylation percentageof app roximate ly 57.72 (defi ned by an IRmethod). Glutaraldehyde (GLA), epichlorohydrin (ECH) . and ethylene glycoldiglyc idyl ether EGDE purchased from Flukawere analytical-reagent grade. All the reagentsused were of ana lytical-reagent grade . Doublydistilled wa ter used to prepare all the solutions.2.2. Preparation of chitosan beadsChitosan solution was prepared by dissolving

2.00 g chi tosan flakes into 50 ml of 5 (v / v)acetic acid solution . The solution was sprayedinto a precipitation bath containing 250 ml of0.50 V NaOH, which neutralized the acetic acidwi thin the chitosan gel and the reby coagulatedthe chitosan gel to spherical uni form chitosangel beads. The aqueous NaOH solution wasstirred using magnetic stirrer. The wet chitosangel beads were extensive ly rinsed with distill edwater to remove any NaOH, filtered and finallyair dried to remove the water from the porestructure (hereafter called chitosa n beads) . Thebeads were then ground by using a laboratoryja r mill and sieved to a constant size 250ur before use .2.3. Preparation of cross-linked chitosanbe s

Three different cro ss-linking agents used tomodify chitosan at a ratio of I : I (chitosan.crossl inking agent).


3/10

WS . \\ Ngah et al. / Reactive Functional Polymers 50 2002) /8 90

- - - - - -183

2.3.1. Glutara ldehyde LChirosan-glu raraldehyde beads were prepared

using a similar procedure to that described byGuibal et al. [18]. Recently prepared wetchitosan beads s de scribed before ) were suspended in 0.05 M glutaraldehyde solution toobtain a ratio of I : I with chitosan. The chito sanbeads in resulting gluta raldehyde solution wereleft standing for 24 h at room temperature. After24 h the cross-linked chitosan bead s wereinten sively washed with distilled water, filteredand air-dried . The newly formed beads hereafter called chitosan-G l.A beads) were groundto a cons tant particle sze 250 u beforeuse. The chitosan-Gl.A beads as shown in Fig.I ) obtained were confirmed by a Perkin-ElmerFT-IR System 2000 Medel spectrometer.2.3.2. Epichlorohydrin /ECH)Chitosan-epichlorohydrin beads were prepared acco rding to the following proceduredesc ribed previously l )]. A solu tion of 0.010M epichlorohydrin containing 0.067 M sodiumhydroxide was prepared pH 10). Freshly prepared wet chitosan beads were added to thisepichlorohydrin solution to obtain a ratio of I: Iwith chi tosan . The chi tosan beads in epichlorohydrin were heated to a temperaturebetween 40 and 50 for 2 h and stirredcon tinuously. After 2 h the beads were filteredand washed intensively with distilled water toremove any unreacted epichlorohydrin and airdried . The newly forrred cross-linked beadshereafter called chitosan-Ef.H beads) wereground to a constant size 250 u rn) beforeuse. The chitosa n-ECH beads s shown in Fig.I ) obta ined were confirmed by a Perkin-ElmerFT-IR System 2000 Model spectrometer.2.3.3. Ethylene gLycoLdiglycidyl etherEGDE)Chitosan-ethylene glycol diglycidyl etherbeads were obtained by a procedure described

by Zeng and Ruckenstein [16]. Chitosan beadswere prepared as mentiened earlier. A solutioncontaini ng 5 v/v) EGDE was prepared andadded to the wet chitosan beads with a I: I

stoichiometric ratio between amino funct ionsand ether groups. The resulting solution wereheated to a temperature 50 60C for 3 handstirred conti nuously . After 3 h. the newly crosslinked chitosan beads were intensively washedand air-dried. The beads hereafter calledchitosan-EGDE beads) were ground to a constant particle size < 250 u before use. Thechitosan-EGDE beads as shown in Fig . I )obtained were confirmed by a Perk in-Elmer FTIR System 2000 Model spectrometer.2 4. Dissolution and swelling test of chitosanand cross-linked chitosan beadsChitosan and cross-linked chitosan beads

were tested with regard to their solubi lity ineach of 5 v/ v) acetic acid. distilled water and0.10 M sodium hydroxide solut ion by adding0.10 g of chitosan and cross-linked chitosanbeads in each of the dilute acid, dis tilled waterand dilute alkaline solutions for a period of 24 hwith stirring.The swelling studies of chitosan and cross

linked chitosan beads were carried out in distilled water at room tempe rature for a period of24 h. The percentage of swelling of these beadswere calculated by using the following equation:

Ws - WPercentage of swelling = W X 100 I )where W, is the weight of swollen beads g) andW is the weight of dry beads g).2.5. Adsorption experimentsA stock solution l000 ppm) of CuIl) ions

was prepared from analytical-reagent grade Cumetal BDH). This stock solution was thendiluted to give standard solution of 5 ppm.Batch adso rption experiments were conductedin 250 ml beaker and equilibrated using amagnetic stirrer. Then 100 ml aliquots of thesestandard solutions were placed in 250 ml beakers and equilibrated with 0.0109 of chitosan orcross-linked chitosan beads. After filtration, the


4/10

184 Wall vgah et al . 1 Reactive Functional Polvmers 50 lOOl ) J - 190

N/

a

c

N

b

b H ~ b HI IOH OH

dFig. I. Schematic representation of the chitosan and cross-liuked chitosan beads: a chitosun. b chitosan-glutaraldehyde chitosan-Gl.A ,c chitosan -epichlorohydrin chitosan-ECH . d chitosan-ethylene glycol diglycidyl ether chitosan-EGDE.

concentration of Cl.i lI in supernatant wasanalyzed using atomic absorption spectroph otonieter Instrumental Laboratory lLAAS357 Model . The effect of Cu l I adsorptionwas studied in the pH range of about 1 6. ThepH of the initial solution was adjus ted to the pHvalue using 0.10 M HN0 3 or 0.10 M NaOH.

Chitosan and cross-linked chitosan beads wereequ ilibrated at the particular pH for about 30min and at an initial Cu II concentration of 5ppm . Th e effect of agitation period and agitationrate also studie d to det ermined the optimumcondition for adsorpt ion of Cu l I ion s.

Ad sorpti on equilibr ium studies were COI1


5/10

\V.S. I\all ,vgai l et al. I Reactive Functional Polymer, 50 lOOl ) 181 90 185

ducted using a contaet time of 60 min at pH 6.0for chitosan , chitosa.i-G l.A and chi tosan-ECHbeads wher eas for chitosan-EGDE beads, acontact time of 90 min at pH 6.0. Isothermstudies were conducted with a constant chitosanand cross-linked chitosan bead s we ight (0 .010g ) and varying initial concentration of CurIl ) inthe range 0-14 ppm. The amount of adsorptionwas ca lculated based on the difference of Cut Il )concentration in aqueous before and after adsorption, the volume of aqueous solution ( 100ml ) and the weight of the beads (0.0 9 )according to :

. (Co - CJVAdsorption capacrty X = W (2)where Co is the initial Cu l l ) concentration(ppm). is the final or equilibrium Cu(ll )concentration (ppm), 1/ is the vo lume of Cut ll)so lution (ml), and W is the weight of thechitosan or cross-l inked chitosan beads (g) .

For de sorpt ion studies, 0.0 9 of chitosanand cross-linked chitosan beads we re loadedwith rl ) using l ml of 5 ppm Cutll)solution at optimum pH and an agitation periodof 60 min was given for chitosan, chitosan-ECHand chitosan-Gl.A beads and 90 min forchitosan-EGDE beads. The agitation rate wasfixed at 500 rpm for all the bead s. Cu ll -Ioadedchitosan and cross-linked beads were co llected ,gently washed with dis ti lled wa ter to removeany unabsorbed Cut ll ). The amount of Cu l l )adsorbed per gram of chitosan and cross-linkedchitosan beads were determined by using thesupernatant Cu l l ) concentration. The chitosanand cross-linked chitosan beads were agi ta tedwith 100 ml of EDTA of vari ous concentrationsTable ISolubilit y effect of chitosan anJ cross-linking chitosan beads

- 10- 6 M) and the amount o f desorbedCu l l ) was de termined as before .

3. Results n discussion

3.1. Solubility and swe lling test of chitosanand cross- linked chitosan beadsIt wa s shown that after cross-linking, the

cross-linked ch itosan was found to be in solublein ac idic and alka line med ium as well asdis ti lled water (Table I ). It is we ll known thatthe high hydrophilicity of chitosan beads or rawchitosan due to a primary amine group makeschi tosan easily so luble in dilute ace tic or formicacid solutions to yield a hydrogel in water. Theswe lling behavio ur of chitosan also improvedafter cross-linking. A co nvenient proof of crossli nking is the swelling behaviour of the crosslinked chitosan beads in di lu te acetic acid. Thus,cross-linking treatment should be nece ssary tore in force the chemical stability of the beads insuch ~ i l i sol ution. M eanwhile, the les s swelling behaviour of cross-linked chitosan beadswas important so they can be used in anads orption column . The percentage of swellingof chitosan and cross-linked chitosan beads aregiv en in Table 2.3.2. Ef fect of pHFig. 2 shows the effect of pH on the ad

sorption of Cu l l ) by chitosan and cros s-linkedchitosan beads. The ad sorption increases ( i.e .,the di fference in abs orbance increases) w ithincreasing pH of the so lution. This co uld be

Beads

Chi tosanChitosan-GLAChitosa n-ECHChitosan-EGDE

Solub ility effect5 v v) Acetic ac idSolubleInsolubleInsolubleInsoluble

Distilled waterInsolubleInsolubleInsolubleInsoluble

0.10 M NaOHInsolu bleInsolubleInsolubleInsoluble

- - - - - --- - - - - - - - - - - - -


6/10

186 irS. mill Nguh et al. I Reactive Functional Polymers 50 2002) 181 90Table 2Swell ing beha viour of chitosan and cross-linked chitosan bead sBeads Swelling ( )

5 v / v Acetic acid Disti lled water 0.10 M NaOHChitosanChitosan GLAChitosan-EC HChi tosan -EGDE

Solub le15.620.614 .1

39.811.917.56.2

35.99.513.64 .5

CS-ECH___ CS-EGDE CS-GLA CHITOSAN

0.160 . . . .0.120

0.000 t t t jo 20 40 60 80 100Agitation Period (minutes)

0.080E ' 0.040

Fig . 3. Ef fec t of agitation pe riod on the adsorp tion of Cu onchitosa n and cross-linke d chi tosan beads; A. abso rbance.

8

CS-ECH___ CSEGDE CS-GLA CHITOSAN

60.000 - - - - jo

0.120

0.080.tE


7/10

IVS. IVall Nguh et al. / Reactive Funct ional Polymers 50 2002 181 90 187

0.160 --- - - -

CSECH CS-EGDE CS-GLAX CHITOSAN

8c. (ppm)2

0.16 .,--- - - - - - - - - - - -

0.04

::J 0.12ECS 0.08X

cross-linked chitosan beads at equilibri um concen tration (mg g- I), Xm ax is the maximumadsorption at monolayer coverage (mg g - I andb is the Langmuir adsorption equilibrium constant (ml mg- I and is a measure of the energyof adsorption.

A linearized plot of Ce versus C, (Fig. 6 )gives max and b Tabl e 3 lists the calculatedresults. It shows that the Langmuir equation bestfits for Cu(II ) adsorption on the chitosan andcross-linked chitosan beads under the concentration range stud ied (correlation coefficient, r>0.99 ). Cross-linking treatment decreases adsorption performances involving a decrease in thenumber of free amine groups, a decrea se in theaccessibility to the internal sites or block anumber of adso rption sites.

It has been reported that the effect of isotherm shape with a view to pred ict ing if anadso rption system is favourable or unfavourable [20]. The essential features of a

(3 )

CS-ECH---+- CS-EGDE CS-GLA CHITOSAN

80000 400 600Agitation Rate (rpm)

0.120

0.000 - - - - - -1 - - - ----4o

0.040


8/10

- - - - - - - - - - - - -188 W5. lI illl Ngah et al, / Reactive : Functional Polyme rs 50 l OO: ) 8 - 9

Langmuir isotherm can be expressed in terms ofa dimensionless constant separation fac tor orequilibrium parameter, RL wh ich is defined by[21]:

of ad sorption may be affected by metal ionconcen trat ion, agitation period and rate . The laststep of the adsorption is considered as a ratedetermining step and as a relatively rapid process .

where Co is the initial Cu U ) concentration ppm), and b is Lan gmuir adsorption equi librium cons tant ml mg - 1 . The p ar ameter indicates the isotherm s hape accor ding to Table 4.

The values of RL calcu lated for differentinitia l Cu lI ) concentration for chitosan andcross-linked chitosan beads are given in Table5. The RL values show that favourable adsorpti on of Cu U) on chi tosa n and cro ss-linkedchit osan bead s takes place. ther efore chit osanand cross -linked chi tos an bead s are favourableadsorbers.Chit osan and cro ss-linked chitosan bead s canbe considered to be m icroporous biopo lymers;therefore pores are large enough to let urIl)ions through . The mechanism of ion adsorptionon porous adsorbents mainly follo ws three steps[22]: i) diffusion of ions to the ex ternal surfaceof adsorbent, ii) diffusion of ions into the poresof adsorbent, and iii) adsorption of the ions onthe internal sur fac e of adsorbent. The first step

RL = 1+ o

T abl e 4Effect of separat ion factor o n iso th e rm shapeRI. va lueRI. > 1R = 1l.O


9/10

II S. \ < Ngah et al / Reactive Functional Po/villers j O l 1 181- 190Tab le 6Percentage of desorption of Cui II) from co mplex Cut ll j-chitosan and cross-linked chitosan beads

189

Concentra tionof EDTA M )LOX 10- LOX 10 - 3LOX 10- LOX 10 - 5LOX 10- 0

D ~ s o r p t i o ( )Chitosan

6 5 2 ~

34.3 15.88

Ch itosan-GLA95.3886.82

5 534 .4010.6 1

Chitosan -ECH97.67

5 ~71.0922.2 27.0 1

Chi tosan-EGDE82.3063 .03

21.90

show lower percentage of swelling . These twocharacters are essentialtor an adsorbent so thatit can be used as a resin in ion-exchangechro matography columns. Moreover , crosslinked chitosan beads show better desorptionresults at higher concentration of EDTA, whereas chitosan beads soluble in higher concentration of EDTA. Therefore, cross-linkedch itosan beads can be regenerated well compared to chitosan beads.

Notation

Xma x Maximum adsorption capacity (mgg- I )

AcknowledgementsThe authors thank Universiti Sain s Malaysia

for the financial support under IRPA Short TermResearch Grant (grant No. SI PKIM 622183).

ReferencesAA l ina ,A ini t i aJb

ECHEDTAEGDEFT-IRGLA

rpmVWWX

Absorbance of Cu(l ) the solutionFinal absorbance Cu(lI ) solutionInitial absorbance of Cu (l I) solutionLangmuir adsorption equilibrium- Iconstant (ml mg )Final or equilibrium concentrationof Cu(II) solution (ppm)Initial concentration of Cu(II ) solution (ppm)Epichloroh ydrinEthylenediarr.inetetraacetic acidEthylene glycol diglycidyl etherFourier transrorm infraredGlutaraldehydeCorrelation coeffic ientDimensionless constant separationfactor or equ :librium parameterRound per minVolume of the Cu(II ) so lution (ml )Weight of dry beads (g )Weight of swolle n bead s (g)Adsorpti on capacity (mg g - I )

[ I] V K. Gupta. Iud. Eng. Chem. Res. 37 ( 1998) 192 .[2] B.Volesky. Z.R. Ho lan . Biotechnol. Bioeng. Prog . I I ( 1995)

235.[3] M. Tsezos, B. Volesky, Biotechnol. Bioeng . ~ ( 1982) 385.[4 ] R.H. Crist, J.R. Ma rtin , J. Chanko , D.R. Cris t . Environ. Sci.

Tech nol. 30 (1996) 2456.[5] c,x . Eiden , c.x . Jewell, J.P. Wightman. J. Appl. Polym. Sci.

25 (1980) 1587.[6] M. Jansson-Charrie r. E. Guiba . J. Roussy. B. Delanghe, P.Le Cloirec. Water Res. 30 ( 1996) 465.[7] F.e . Wu. R.L. Tseng. R.S. Juang , J . Hazardou s Mate r. B3

(2000) 63.18] R. Maruca. B.J. Suder. J.P. Wightman. J . Appl. Polym . Sci.

27 ( 198 2) 4827.[9 J E. Guibal , Jansso n-Charier . I. Saucedo , P. Le Cloirec ,

Langmuir 11 (1995) 59 I.[10] T .Y. Hsien, G.L. Rorrer . Ind. Eng. Chem. Res. 36 (1997 )

3631.[I I ] W Sw. Ngah. lsa, J. Appl. Polym. Sci. 67 ( 1998) 1067.[12] WSW . Ngah, K.L. Liang. Ind. Eng. Chern. Res. 38 ( 1999)

141 I.[ 13] Peniche-Covas. L.W Alva rez. W. Arg ue lles-Monal, J.

App l. Polym. Sci. 46 ( 1992) 1147.[l 4] I. Saucedo. E. Guibal , J. Rou ssi , P. Le Cloirec, Water SA 19

(2) (1993 ) 113.[15] K. Inoue. Y. Buba, K. Yoshi guza, Bull. Ch ern. Soc. Jpn. 66

( 1993) 2915 .l16 ] X. Ze ng , E. Rucken stein, J . Mernbr. Sci. ~ (1998) 195.

- - -


10/10

190 WS. ll Ngah et al. / Reactive Fun ctional Polymers 50 2002 181 90

[17] Y Koyama. A Taniguchi. JAppl. Polyrn. Sci. 31 1986)95

[18J E. Guibal, C. Milot, O. Eterradossi, C. Gauffier, A. Domard ,Int. J. BioI. Macrornol. 24 199 9) 49.

[I 9J vcWei, Hudson, J.M. Mayer, D.C. Kaplan. J. Polyrn.Sci ., Pan A: Polym. Chern. 30 1992) 2 187.

[20J Weber, R.K. Chakravorti. AIChE J. 20 1974) 228 .[21] K.R. Hal l. c . Eagleton. A. Acrivos, T. Vermeulen. Ind.

Eng . Chern . Fundam. 5 [996) 212 .[22] C. Peniche -Covas, L.W Alvarez. W Arguelles-Mouat, J.

Appl. Polym. Sci . 39 19 90 ) 739.

Documents

Removal of Copper II Ions Aqueous Solution Onto