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1 JASEM ISSN All rights rsrvd Full-txt Availabl Onlin at J. Appl. Sci. Environ. Manag. Jun, 28 Vol. 12(2) Equilibrium Sorption studis of F, Cu and Co ions in aquous mdium using activatd Carbon prpard from Rcinius Communis Linn. KARTHIKEYAN, G; SIVA ILANGO, S Dpartmnt of chmistry,gandhigram Rural Univrsity, Gandhigram , Tamil Nadu,India. -mail: drg_karthikyan@rdiffmail.com Tl.: Fax: ABSTRACT: Rcinius Communis Linn a commonly found hrbal plant was usd to prpar activatd carbon by physicochmical activation mthod. Th sorption capacity of this bio-rsourc matrial to rmov F(III), Cu(II) and Co(II) from aquous solutions was dtrmind by batch tsts. Th influncs of important paramtrs such as contact tim, dosag, ph, ph zpc, co-ions and tmpratur on mtal adsorption procss wr invstigatd. Th quilibrium data wr fittd to Langmuir and Frundlich isothrms. Th batch adsorption rat for th sorption procss was xplaind on th basis of intraparticl diffusion. Various thrmodynamic paramtrs lik G, H and S wr analyzd to obsrv th natur of adsorption. Th mtal adsorption procss on th surfac of adsorbnt was vrifid as a surfac phnomnon by prforming SEM and XRD JASEM Mtals can b distinguishd from othr toxic pollutants, sinc thy ar not biodgradabl and can b accumulatd in living tissus, causing various disass and disordrs. Convntional mthods for rmoving mtals from industrial fflunts includ chmical prcipitation, coagulation, solvnt xtraction, lctrolytic procsss, mmbran sparation, ion xchang, rvrs osmosis, ultra filtration, biological systms and adsorption (God and Phlivan, 25) Adsorption procsss for rmoval of mtals hav bn found chapr and mor ffctiv than th svral tchnologis. (Gupta t al., 23) Numrous by products of agro industrial productions and agricultural by products hav bn studid for potntial us as inxpnsiv sorbnts. (Ho, 23) Many xampls ar availabl in th litratur concrning th dirct or activatd us of ths matrials as adsorbnts. (Cochran t al, 26; Baily t al, 1999; Abia t al, 22) This study dals with th invstigation of F(III), Cu(II) and Co(II) rmoval from aquous solutions by adsorption on activatd carbon prpard from Rcinius Communis Linn (RC). MATERIALS AND METHODS Th prparation of activatd carbon from RC consistd of carbonization of th plant matrial. Drid raw lavs wr cut into small pics and th carbonization was conductd in a muffl furnac at 4 C. Th hating priod was 2 hours. Aftr carbonization, th carbon was ground using domstic mixi. Th activatd carbon obtaind was kpt in a dsicator and wr charactrizd for th physical paramtrs which ar givn in Tabl 1. Adsorption quilibrium study of ths mtal ions was carrid out in 25ml stopprd Iodin flask. Th concntration of th mtal ions was dtrmind by UV/ Visibl spctrophotomtr (UV 24 Shimaduzu). All othr watr quality paramtrs wr analyzd by using standard mthods (APHA, 1998). Th ph masurmnts wr don with a ph lctrod (Systronics) and ph ZPC (ph of zro point charg) was dtrmind by ph drift mthod. (Jia t al, 22) Th surfac morphology of th raw and tratd activatd carbons was visualizd by SEM with a HITACHI-S- 3H modl. XRD pattrn was rcordd using X 1 pr PRO (modl), PAN analytical (mak). Computations wr mad using Microcal Origin, (vrsion 6.) softwar. Tabl 1. Charactristics of th activatd carbon S.No Paramtrs Rcinius Communis Linn 1 Particl siz (mm).15 2 Dnsity (g/cc).54 3 Ash contnt (%) Moistur contnt (%) Loss of ignition (%) Watr solubl mattr.17 7 ph of aquous solution ph (zpc) Iodin numbr (mg/g) 24 Tabl 2. Langmuir and Frndlich constants Langmuir constants Frundlich constants Mtal ions Tmpratur Q b R 2 R L 1/n K f R F(III) Cu(II) Co(II)

2 82 RESULTS AND DISCUSSION Th ffct of tim on th adsorption of mtal ions by RC for iron(iii), coppr(ii) and cobalt(ii) with 5ml of 2 ppm of ach mtal ion solutions wr studid. Fig.1 shows th ffct of contact tim on adsorption of th adsorbnt. Th ffct of th activatd carbon RC dos on th rmoval of mtal ions is shown in fig.2. Th adsorption incrasd from 45 to 9 prcntags with incras in adsorbnt dos from 5 mg to 5mg. Th ph dpndnc of iron(iii), coppr(ii) and cobalt(ii) tak onto RC is shown in fig.3. It is wll known that ths mtal ions undrgo hydrolysis ractions in watr and form insolubl complxs with incrasing ph. (Jams and Haly, 1972) This phnomnon is concdd as important for undrstanding th adsorption bhaviour of all mtal ions onto ths activatd carbons. Up to ph 5. du to th prsnc of H + ions of th acid usd for adjusting ph. Howvr, this ffct causs in th ph rang of (Clik t al, 1995) Th influnc of 2 othr co-ions such as Cl, SO, 2+ HCO, NO, Ca, and Mg which ar commonly prsnt in watr, on th adsorption of iron(iii), coppr(ii) and cobalt(ii) by th activatd carbon was invstigatd. Fig. 4 givs th ffct of co-ions on th adsorption of coppr(ii) as rprsntativ plot. In all th cass, th prsnc of ths co-ions did not significantly altr th mtal ions adsorption procss by th activatd carbon. Equilibrium data ar basic rquirmnts for th 4 dsign of adsorption systms and adsorption modls ar usd for th mathmatical dscription of th adsorption quilibrium of th mtal ions on to th adsorbnt. Th rsults obtaind on th adsorption of iron(iii), coppr(ii) and cobalt(ii) wr analyzd by th wll known modls givn by Langmuir and Frundlich. Langmiur isothrm. Th linar form of Langmuir isothrm quation is givn as C 1 1 = + C, (1) q Q b Q whr C is th quilibrium concntration of th adsorbat (mg/l), q is th amount of adsorbat adsorbd pr unit mass of adsorbnt (mg/g), Q and b ar Langmuir constants rlatd to adsorption capacity and rat of adsorption. Th Langmuir curvs prtaining to th Cu(II) adsorption by RC is providd in fig.5 as rprsntativ plot. Th Langmuir constants b and Q o wr calculatd from quation (2) and th valus ar givn in Tabl 2. Th ssntial charactristics of th Langmuir isothrm can b xprssd in trms of a dimnsionlss quilibrium paramtr (R L ) which is dfind by, 1 R =, (2) L 1 + bc whr b is th Langmuir constant and C is th initial concntration (mg/l). Th valu of R L indicats th typ of th isothrm to b ithr favourabl ( < R L < 1), unfavourabl (R L > 1), linar (R L = 1) or irrvrsibl (R L = ) 1 9 Prcntag of mtal ions rmovd F(III) Cu(II) Co(II) tim in mins Fig.1. Effct of contact tim for RC

3 Prcntag of mtal ions rmovd F(III) Cu(II) Co(II) dos in gms Fig. 2. Effct of dos for RC 1 9 Prcntag of mtal ions rmovd 8 7 F(III) Cu(II) Co(II) ph Fig. 3 Effct of ph for RC Prcntag of mtal ions rmovd HCO 3 2- SO 4 - NO 3 Cl - Ca 2+ Mg concntration of co-ions (mg/l) Fig. 4. Effct of co-ions

4 c / q o C 4 o C 5 o C c Fig. 5. Langmuir plot of RC logq o C 4 o C 5 o C log c Fig. 6. Frundlich plot for RC (Mor t al, 27). Th valu of R L was found to b lss than on and this again confirmd that th Langmuir isothrm modl was favourabl for adsorption of mtal ions onto th activatd carbon undr th conditions usd in this study. Frundlich isothrm Th wll-known logarithmic form of Frundlich isothrm is givn by th following quation, 1 log q = log K f + log C, (3) n whr C is th quilibrium concntration of th adsorbat (mg/l) and q is th amount of adsorbat adsorbd pr unit mass of adsorbnt (mg/g). K f and n ar Frundlich constants rprsnting th adsorption capacity and intnsity of adsorption rspctivly. Th valus of K f and 1/n wr obtaind from th slop and intrcpt of th plot of log q vrss log C. Th slop of l/n ranging btwn and 1 is a masur of adsorption intnsity or surfac htrognity, bcoming mor htrognous as its valu gts closr to zro. (Raji and Anirudhan, 1997) Frundlich constants K f and n valus wr calculatd and listd in Tabl 2 and th plot is givn in fig.6. Thrmodynamic paramtrs with th adsorption viz., standard fr nrgy chang ( G ), standard nthalpy chang ( H ) and standard ntropy chang ( S ) wr calculatd using th quation blow and th valus ar givn in Tabl 3. Tabl 3. paramtrs for ions at 2 ppm Mtals G o ( KJmol -1 ) H o (KJmol -1 ) S o (KJmol -1 ) 33K 313K 323K F(III) Cu(II) Co(II) Thrmodynamic sorption of mtal

5 85 o G = RT ln Ko, (4) whr th G is th fr nrgy of adsorption, T is th tmpratur and R th Univrsal gas constant. Th adsorption distribution cofficint K o for th adsorption raction was dtrmind from th slop of th plot ln(q / c ) against C at diffrnt tmpratur and xtrapolating to zro C according to mthod suggstd by Khan and Singh. (Khan and Singh, 1987) Th adsorption distribution cofficint may b xprssd in trms of nthalpy chang ( H ) and ntropy chang ( S ) as a function of tmpratur, o o H S ln K = +, (5) RT R Whr th valus of H and S can b obtaind from th slop and intrcpt of th plot of ln K against 1/T. (Mnakshi and Viswanathan, 27) From a mchanistic point of viw, to intrprt th xprimntal data, production of th rat-limiting stp is an important factor to b considrd in th sorption procss. Though kintic and quilibrium isothrm studis hlp to idntify th adsorption procss, prdicting th mchanisms is rquird for dsign purpos. For a solid - liquid sorption procss, th solut transfr is usually charactrizd by ithr xtrnal mass transfr (boundary layr diffusion) or intraparticl diffusion or both. This is dtrmind by plots of th amount of mtal adsorbd against th squar root of tim, t ½ for thr diffrnt tmpraturs. According to Wbr, an intraparticl diffusion cofficint is dfind by th quation. 1/ 2 qt = K pt, (6) q t = th amount of mtal ions adsorbd pr unit mass of adsorbnts at any tim t t 1/2 = squar root of tim K p = Intraparticl diffusion rat constant q t mg / L 4 mg / L 6 mg / L at 3 o C t 1/2 Fig. 7. Effct of intraparticl diffusion for RC Fig. 8. a) SEM for RC bfor tratmnt b) SEM for RC aftr tratmnt

6 86 C ounts 1 outsid work2_ P o s itio n [ 2 T h ta ] Fig.9 a) XRD for RC bfor tratmnt Counts outsid work2_ P osition [ 2Thta] Fig.9 b) XRD for RC aftr tratmnt Th plots of intraparticl diffusion curvs shows initial curvd portion followd by linar portion and a platau. Th first sharpr portion is th xtrnal surfac adsorption or instantanous adsorption stag. Th scond portion is th gradual adsorption whr th intraparticl diffusion is rat controlld. Th third portion is final quilibrium stag whr th intraparticl diffusion starts to slow down du to xtrmly low solut concntration in solutions. (Chnung t al, 27) Fig.7 shows Cu(II) adsorption by RC as rprsntativ plot. SEM imags of th activatd carbon bfor and aftr of iron(iii) sorption ar shown in fig.8 abov as rprsntativ imags. Comparison of ths micro graphs bfor and aftr iron(iii) sorption shows that thr adsorption of mtal ions on th surfac of th activatd carbon. XRD pattrns of th tratd adsorbnts showd significant changs. Th XRD data of th tratd activatd carbon providd vidnc of dcras in th pak intnsity at 2Ө valus which shows that adsorption of iron(iii) on th surfac of th adsorbnt and at th sam it dos not altr th crystallin structur of th matrial. (Gopal and Elango, 27) Fig. 9 abov indicat th dcras in th pak intnsity valus aftr adsorption of RC, on iron(iii) as rprsntativ.

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