Availabl onlin www.jocpr.com Journal of hmical and Pharmacuical Rsarch, 214, 6(6):154-159 Rsarch Aricl ISSN : 975-7384 ODEN(USA) : JPR5 Th adsorpion of nickl ions in auous soluion by chiosan gl bads Muing Qiu 1, Shuiying Xiong 2* and Huazhng Xin 2 1 ollg of Lif Scincs, Shaoxing Univrsiy, Shaoxing, Zhjiang, P.R. hina 2 Dparmn of Lif Scinc, Shaoxing Univrsiy Yuanpi ollg, Shaoxing, Zhjiang, P.R. hina ABSTRAT In his sudy, chiosan bads wr producd from chiosan flaks. Th rsarchs on adsorpiv propris of chiosan bads wr carrid ou. Th ffc of ph, conac im, mpraur and iniial concnraion wr invsigad. Th rsuls obaind on h adsorpion of nickl wr analyzd by h wll known modls givn by Langmuir and Frundlich. Th maximum adsorpion capaciy for chiosan gl bads a a mpraur of 293, iniial concnraion of 4mg/L, conac im of 3min and ph 5. in soluion was found o b 3.5mg/g. Thrmodynamic paramrs of h adsorpion procss such as h sandard Gibb s fr nrgy chang, fr nrgy chang ( G ), nhalpy chang ( H ) and nropy chang ( S ) wr calculad. Th rsul showd ha adsorpion of nickl ions in auous soluion by chiosan bads was sponanous and ndodrmic in naur. y words: Adsorpion; Nickl ions; hiosan bads INTRODUTION Th ground and surfac wars polluion by chmical conaminans is a worldwid problm. Havy mal conaminaion of war sourcs is hazardous o plans, animals and microorganism and can b carcinognic o mankind. On h ohr hand, mals ar playing imporan rols in mos indusris [1]. Nickl is usd o mak mal alloys such as sainlss sl. I can b usd as compound fro coloring cramics, nickl-plaing, manufacuring baris and as a caalys [2]. Nickl ions can b rmovd from war or waswar physically or chmically du o h fac ha hy ar unbiodgradabl. Svral chnius hav bn proposd for h rmoval of nickl ions from war and waswar including chmical prcipiaion, mmbran filraion, ion xchang, lcrolysis and adsorpion. Mos of hs mhods ar infficin whn i coms o raing war wih low mal concnraion [3-5]. Th us of chiosan as an adsorpiv polymr in rmoving a wid rang of conaminan has bn a major dvlopmn in h pas yars [6]. hiosan is found abundanly on arh and is obaind by indusrial alkalin dacylaion of chiin. I is worh noing ha among many biopolymrs, chiosan has h highs adsorpion capaciy for mals bcaus h amino and hydroxyl groups on chiosan chains srv as coordinaion sis. Nirogn and oxygn aoms hav fr lcron doubls ha can rac wih mal caions. Srongr aracion of h lon pair of lcrons o h nuclus in an oxygn aom comparing o nirogn aom causs h mor ndncy of nirogn aoms o dona h lon pair of lcrons for sharing wih a mal ion o form a mal complx. So, amino groups ar rsponsibl for h upak mal ion. Also, h high concnraion of mal sal anions causs adsorpion of hs anions by polymr. onsunly, chiosan posssss a ngaivly chargd characrisic and shows addiional abiliy for mal caions by lcrosaic mchanism [7-9]. In his sudy, chiosan gl bads wr producd from chiosan flaks. Th rsarch on adsorpiv propris of chiosan bads was carrid ou. Th ffc of ph, conac im, mpraur and iniial concnraion was invsigad. 154
Shuiying Xiong al J. hm. Pharm. Rs., 214, 6(6):154-159 EXPERIMENTAL SETION 2.1 Prparaion of h adsorbns Th 7% (w/w) chiosan soluion was mad by dissolving 75.3g of chiosan flaks in 1L of 3.% (v/v) acic acid soluion. Th dissolvd chiosan soluion was filrd hrough a polysyrn siv wih mush 1um o rmov impuriis, formaion of chiosan gl bads is said o ak plac whn h filra coms in conac wih 1M of sodium hydroxid soluion. Th produc of chiosan gl bads was hus obaind and hn sord for lar adsorpion xprimns. 2.2 Adsorpion xprimns Adsorpion xprimns wr conducd in a s of 25 ml Erlnmyr flasks conaining.5g of chiosan gl bads and 1 ml of nickl ion soluions wih various iniial concnraions (4mg/L, 6mg/L, 8mg/L, 1 mg/l and 12mg/L). Th iniial ph was adjusd o 5. wih 1 mol/l Hl. Th flasks wr placd in a shakr a a consan mpraur (293, 33 and 313) and 2 rpm. Th sampls wr filrd and h rsidual concnraion of nickl ion was analyzd by aomic absorpion spcrophoomry (AAS). 2.3 Analyical mhods Th amoun of adsorbd nickl ion (mg/g) a diffrn im, was calculad as follows: ( = ) V m (1) whr and (mg/l) ar h iniial and uilibrium liuid-phas concnraions of nickl ion rspcivly. V (L) is h soluion volum and m (g) is h mass of adsorbn usd. 2.4 Saisical analyss of daa All xprimns wr rpad in duplica and h daa of rsuls wr h man and h sandard dviaion (SD). Th valu of h SD was calculad by Excl Sofwar. All rror simas givn in h x and rror bars in figurs ar sandard dviaion of mans (man±sd). All saisical significanc was nod a α=.5 unlss ohrwis nod. RESULTS AND DISUSSION 3.1 Effc of ph in soluion Th ph in soluion is an imporan rgulaing facor in adsorpion procss. Th adsorpion of mal ions by surfac funcional group is highly dpndn on ph in soluion. To drmin h opimum ph for h adsorpion of Nickl(Ⅱ) ions ono chiosan gl bads, h prcnag rmoval of Nickl(Ⅱ) ions as a funcion of hydrogn ion concnraion was xamind a an iniial concnraion of 4mg/L. Effc of ph was showd in Fig.1. As shown in Fig.1, i showd a dcras in h rmoval ra of Nickl(Ⅱ) ions a lowr ph condiions. A lowr ph, hydrogn ions occupy mos of h adsorpion sis on h surfac of h adsorbn and h rsuls o a vry low adsorpion of nickl ions du o lcrosaic rpulsion. Howvr, incrasing h ph of h soluions rsuls o a dcras in h compiion of hydrogn ions wih nickl ions for adsorpion sis and hus faciliaing highr ra of rmoval of nickl ions. Morovr, incrasing h ph abov 6. rsuld o h prcipiaion of insolubl nickl hydroxid, causing a dcras in h rmoval of nickl ions. 3.2 Effc of conac im Th ffc of conac im is imporanc in adsorpion xprimn. Adsorpion of nickl ions ono chiosan gl bads was invsigad a various conac im from 3min o 21min. Th rsuls wr shown as Fig.2. During h firs 3min, h rmoval of nickl ions procds fasr wih im and hn incrass slighly. Finally, i rachs uilibrium. 155
Shuiying Xiong al J. hm. Pharm. Rs., 214, 6(6):154-159 1 8 Nickl rmoval (%) 6 4 2 1 2 3 4 5 6 7 Fig.1 Effc of ph in soluion on rmoval of nickl ions by chiosan gl bads a iniial concnraion of 4 mg/l, conac im of 3min, 293 and 2 rpm 1 ph 8 Nickl rmoval(%) 6 4 2 5 1 15 2 25 Tim(min) Fig.2 Effc of conac im on rmoval of nickl ions by chiosan gl bads a iniial concnraion of 4 mg/l, ph5., 293 and 2 rpm 3.3 Effc of iniial concnraion Th ffc of iniial concnraion was carrid ou a various iniial concnraions of 4-12mg/L. Th adsorpion rsuls wr shown as Fig.3. Th uilibrium occurrd fasr wih iniial concnraion. This obsrvaion is du o h fac ha a lowr iniial nickl ions concnraion, sufficin sis rsponsibl for adsorpion of nickl ions ar availabl. As h concnraion of nickl ions incrass, h numbrs of nickl ions bcom rlaivly highr compard o h availabiliy of adsorpion sis. Hnc, h ra of rmoval of nickl ions is dpndn on h iniial concnraion of nickl ions and also dcrass wih incras in concnraion of nickl ions. 156
Shuiying Xiong al J. hm. Pharm. Rs., 214, 6(6):154-159 1 8 Nickl rmoval (%) 6 4 2 Fig.3 Effc of iniial concnraion of nickl ions on rmoval of nickl ions by chiosan gl bads a conac im of 3min, ph5., 293 and 2 rpm 3.4 Adsorpion isohrm Th capaciy of an adsorbn can b dscribd by is uilibrium sorpion isohrm. Th Langmuir and Frundlich adsorpion modls ar commonly adopd o invsiga h adsorpion bhavior of marials and h corrlaion among adsorpion paramrs. Accordingly, uilibrium daa wr simulad by h Langmuir [1] and Frundlich modls [11]. Th Langmuir isohrm uaion is rprsnd by h following E. (2): Whr (mg/g), m L = (2) 1 + L is h uilibrium concnraion of nickl ions (mg/l), is h maximum adsorpion capaciy of nickl ions (mg/g), and m 2 4 6 8 1 12 14 Iniial concnraion of nickl ions (mg/l) uilibrium consan (L/mg) rlad o h affiniy of h binding sis. Th Frundlich isohrm uaion is dscribd by h following E. (3): is h amoun of nickl ions adsorbd L is h Langmuir adsorpion F 1 n = (3) F and n ar h Frundlich adsorpion isohrm consans, which ar indicaors of adsorpion capaciy Whr and adsorpion innsiy rspcivly. Th corrsponding valus of Langmuir and Frundlich isohrms for nickl ions adsorpion on chiosan gl bads wr lisd in Tabl 1. Th rsuls indica ha h Langmuir isohrm fis br han h Frundlich isohrm, which may b du o homognous disribuion of aciv sis ono chiosan gl bads. Th valu of or is bwn and 1, which indica hrogniy of h adsorbns and favorabl adsorpion [12]. Th maximum adsorpion capaciy obaind from h Langmuir isohrm is 3.5 mg/g. L f 157
Shuiying Xiong al J. hm. Pharm. Rs., 214, 6(6):154-159 Tabl 1 Euilibrium modl paramrs for h adsorpion of nickl ions ono chiosan gl bads. Exprimnal condiions:.5g of chiosan gl bads, conac im of 3 min, 293, 2 rpm and ph 5. in soluion Langmuir modl Frundlich modl m (mg/g) L (L/mg) 2 R f (mg/g) n 2 R 3.5.24.9713.431.4892.945 3.5 Thrmodynamic sudis Th hrmodynamic paramrs of fr nrgy chang ( G ), nhalpy chang ( H ) and nropy chang ( S ) wr usd o dscrib hrmodynamic bhavior of h adsorpion of nickl ions ono h chiosan gl bads. Ths paramrs wr calculad from h following uaions [13]. G = RT ln (4) a S H ln a = (5) R RT a = (6) whr T is h soluion mpraur (), a is h adsorpion uilibrium consan, R is h gas consan (8.314 J. mol -1. -1 ), is h amoun of adsorba adsorbd pr uni mass of adsorba a uilibrium (mg/g) and is h uilibrium concnraion of h adsorba (mg/l). Thrmodynamic paramrs ( H, S and G ) for nickl ions adsorpion wr valuad using Es. (4)-(6). Th valus of H and S wr drmind from h slop and inrcp of h plo of ln a vrsus 1/T. Th valus of H, S and G ar lisd in Tabl 2. Tabl 2 Thrmodynamic paramrs for h adsorpion of nickl ion ono chiosan gl bads G Tmpraur () ( J/mol) 293-1.46 33-4.32 313-5.26 H ( J/mol) 34.29 34.29 34.29 S ( J/mol).21.21.21 G dcrass. I indicad ha lss driving forc and hnc As h mpraur incrass, and h valu of rsuling in lssr adsorpion capaciy a highr mpraurs. Th ngaiv valus of G indicas h adsorpion of nickl ion ono chiosan gl bads is sponanous and hrmodynamically favorabl. Th posiiv valu of H indicad ha h sorpion procss was ndohrmic in naur. Th posiiv valu of S showd h incrasing randomnss a solid/soluion inrfacd wih som srucural changs in h adsorba and h adsorbn and an affiniy of h adsorbn. ONLUSION In his xprimn, chiosan bads wr producd from chiosan flaks. Th chiosan gl bads wr usd in h rmoval of nickl ions in soluion. Th rsuls indica ha h Langmuir isohrm fis br han h Frundlich isohrm. Th valus of h hrmodynamic paramrs rvald ha h adsorpion of nickl ion ono chiosan gl bads is sponanous and hrmodynamically favorabl. Th incrasing randomnss a solid/soluion inrfacd wih som srucural changs in h adsorba and h adsorbn and an affiniy of h adsorbn. Acknowldgmns This sudy was financially suppord by h projc of scinc and chnology plan in Shaoxing iy ( 213B75 ). 158
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