Isotherm Analysis on the Removal of Ni (II) ION from Wastewater using APANC

Transcription

1 Intrnational Journal of Advancd Rsarch in Chmical Scinc (IJARCS) Volum 4, Issu 1, January 2017, PP 1-12 ISSN X (Print) & ISSN (Onlin) Isothrm Analysis on th Rmoval of Ni (II) ION from Wastwatr using APANC S Arivoli *, A Arasakumar PG and Rsarch Dpartmnt of Chmistry, Thiru Vi Ka Govrnmnt Arts Collg, Thiruvarur, Tamilnadu, India. Abstract: Nickl plays an important rol in mtallurgical, lctroplating and othr chmical industris. About 40% of th nickl producd is usd in stl factoris, nickl battris and in th production of som alloys. On th othr hand, it may pollut aquous strams, arising thrfor svral nvironmntal problms. An adsorbnt prpard from Pandanus Amaryllifolius Stm Ash, by acid tratmnt was tstd for its fficincy in rmoving nickl ion. Th procss paramtrs studid includ agitation tim, initial Nickl ion concntration, adsorbnt dos, ph and tmpratur. Th adsorption followd scond ordr raction quation and th rat is mainly controlld by intra-particl diffusion. Th quilibrium adsorption data wr corrlatd with Langmuir, Frundlich, Tmkin, Dubinin-Radushkvich, Hurkins-Jura, Halsay, Radlich-Ptrson, Jovanovic and BET isothrm modls. Th adsorption capacity (Q m ) obtaind from th Langmuir isothrm plot at an initial ph of 6.5 and at 30, 40, 50, 60 ± C. Th influnc of ph on mtal ion rmoval was significant and th adsorption was incrasd with incras in tmpratur. A portion of th nickl ion was rcovrd from th spnt APANC using 0.1M HCl. Kywords: Activatd Pandanus Amaryllifolius Stm Nano Carbon (APANC), Nickl ion, Adsorption isothrm, Equilibrium, Thrmodynamic paramtrs, Intra-particl diffusion. 1. INTRODUCTION Havy mtal pollution of watr and watr bodis is a srious nvironmntal problm that affcts th quality of watr. Th consquncs ar dcrasing watr supply, incras in cost of purification, utrophication of watr bodis and dcras in aquatic production [1]. In ordr to tackl th mnac pois by havy mtal pollution of watr, svral options hav bn adoptd. Ths includ oxidation and rduction, chmical prcipitation, filtration, lctrochmical tratmnt, ion xchang, mmbran sparation, rvrs osmosis, adsorption, vaporation and lctrolysis [2]. Howvr, adsorption has bn provn to b on of th bst options availabl for th rmoval of havy mtals from aquous solution [3, 4]. In viw of th abov, svral rsarchs hav bn conductd using various matrials as adsorbnts [5-7]. Howvr, som of ths adsorbnts also contain othr toxicants; som ar xpnsiv and ar charactrizd with limitd surfac ara for adsorption. A sarch of litratur rvald that fruit ston has bn usd for adsorption of som havy mtals from aquous solution but litratur is scanty on th us of activatd carbon producd from fruit ston for th adsorption of Ni(II) ions from aquous solution. Thrfor, th objctiv of th prsnt study is to invstigat th possibility of using APANC. 2. MATERIALS AND METHODS 2.1. Adsorbnt Pandanus Amaryllifolius Stm ARC Pag 1

2 S Arivoli & A Arasakumar Th Pandanus Amaryllifolius Stm collctd from narby Thiruvarur district was Carbonizd with concntratd Sulphuric Acid and washd with watr and activatd around 1100 C in a muffl furnac for 5 hrs th it was takn out, ground wll to fin powdr and stord in a vacuum dsiccators Chmicals All chmicals usd of high purity commrcially availabl Analar grad mg/l of stock solution of nickl was prpard by dissolving accuratly wighd gram of nickl sulphat in 1000 ml distilld watr. All xprimntal solutions wr prpard by diluting th stock solution to th rquird concntration. Th ph of ach xprimntal solution was adjustd to th rquird initial ph valu using dilut HCl (or) NaOH bfor mixing th adsorbnt. Th concntration of rsidual nickl ion was dtrmind with atomic absorption spctrophotomtr (Prkin Elmr 2380) Batch Exprimnts Th ffct of various paramtrs on th rmoval of nickl ion onto APANC was studid batch adsorption xprimnts wr conductd at (30-60 C). For ach xprimntal run, 50 ml of nickl solution of known initial concntration and ph wr takn in a 250 ml pluggd conical flask. A 25 mg adsorbnt dos is addd to th solution and mixtur was shakn at constant agitation spd (150 rpm) sampl wr withdrawn at appropriat tim intrvals (10-60 min) and th adsorbnt was sparatd by filtration. Th rsidual solutions wr analyzd to dtrmin th nickl ion concntration. Th ffct of dosag of adsorbnt on th rmoval of nickl ion was masurd by contacting 50 ml of 50 mg/l of nickl ion solution with 25 mg of APANC till quilibrium was attaind. Adsorption quilibrium isothrm is studid using 25 mg of APANC dosag pr 50 ml of nickl ion solution. Th initial concntration wr rangd from (10 to 50 mg/l) in all sts of xprimnts. Th pluggd conical flask was shakn at a spd of 150 rpm for 60 minuts. Thn th solution was sparatd from th mixtur and analyzd for nickl ion concntration. Th adsorption capacity was calculatd by using a mass quilibrium quation as follows: q = (C 0 - C ) V/M (1) Whr C 0 and C bing th initial nickl concntration (mg/l) and quilibrium concntration, rspctivly V is th xprimntal volum of nickl ion solution xprssd in litrs [L] and M is th adsorbnt mass xprssd in grams [g]. Th nickl ion ions prcntag can b calculatd as follows: %R = (C 0 C t ) x 100/C 0 (2) Th ffct of ph on th rat of adsorption was invstigatd using nickl concntration of 20 mg/l constant APANC dosag. Th ph valus wr adjustd with dilut HCl and NaOH solution. Th adsorbnt-adsorbat mixtur was shakn at room tmpratur using agitation spd (150 rpm) for 60 minuts. Thn th concntration of nickl in solution was dtrmind. 3. RESULTS AND DISCUSSION 3.1. Effct of Agitation Tim and Initial Nickl Ion Concntration Fig1. Effct of Contact Tim on th Rmoval of Nickl I on [Ni]= 50 mg/l; Tmpratur 30 o C; Adsorbnt do s =25 mg/50ml Intrnational Journal of Advancd Rsarch in Chmical Scinc (IJARCS) Pag 2

3 Isothrm Analysis on th Rmoval of Ni (II) ION from Wastwatr using APANC Th kintics of adsorption of nickl ion by APANC is shown in (fig. 1) with smooth and singl plots indicating monolayr adsorption of mtal ion on th APANC. Th rmoval of mtal ion incrasd with th laps tim and attains quilibrium in 60 min for 50 mg/ L. With incras in mtal ion concntration from 10 to 50 mg/l, th amount of mtal ion adsorbd incrasd whil th prcnt rmoval dcrasd, indicating that th mtal ion rmoval by adsorption on APANC concntration dpndnt Effct of APANC Mass Th amount of nickl ion adsorption incrasd with th incras in APANC dos and rachd a maximum valu aftr a particular dos (fig.2). Takn an initial mtal ion concntration of 20 mg/l, complt mtal ion rmoval was obtaind at a maximum APANC dos of 125 mg. Th incras in th adsorption of mtal ion with APANC dos was du to th introduction of mor binding sits for adsorption and th availability mor surfac ara. Fig2. Effct of Adsorbnt dos on th rmoval of Ni Ion [Ni]= 50mg/L; Contact Tim 60m in; Tmpratur 30 o C 3.3. Effct of ph Th xprinc carrid out at diffrnt ph show that thr was a chang in th prcnt rmoval of mtal ion ovr th ntir ph rang shown in Fig. 3. This indicats th strong forc of intraction btwn th mtal ion and APANC that ithr H + or OH - ions could influnc th adsorption capacity. In othr words, th adsorption of mtal ion on APANC dos involv ion xchang mchanism that hav bn an influnc on th mtal ion adsorption whil varying th ph This obsrvation is in lin with th typ I and II isothrm and positiv H 0 valu obtaind, which indicats irrvrsibl adsorption probably du to polar intractions. Fig3. Effct of Initial ph on th rmoval of Ni Ion [Ni]= 50mg/L; Tmpratur 30oC; Adsorbnt dos= 25mg/50m1 Intrnational Journal of Advancd Rsarch in Chmical Scinc (IJARCS) Pag 3

4 S Arivoli & A Arasakumar 3.4. Effct of Othr Ions Th ffct of othr ions lik Ca 2+ and Cl - on th adsorption procss studid at diffrnt concntrations. Th ions addd to 50mg/L of mtal ion solutions and th contnts wr agitatd for 60 min at 30 0 C. Th rsults had shown in th Fig. 4 rvals that low concntration of Cl - dos not affct th prcntag of adsorption of mtal ion on APANC, bcaus th intraction of Cl - at availabl sits of adsorbnt through comptitiv adsorption is not so ffctiv. Whil th concntration of othr ion Ca 2+ incrass, th intrfrnc of ths ions at availabl surfac sits of th sorbnt through comptitiv adsorption incrass that, dcrass th prcntag adsorption. Th intrfrnc was mor in th prsnc of Ca 2+ compard with Cl - ion. This is so bcaus ions with smallr hydratd radii dcras th swlling prssur within th sorbnt and incras th affinity of th sorbnt for such ions. Fig4. Effct of ionic strngth on th adsorption of Nickl ion [Ni]=50 mg/l; ph=6.5; Dos=25mg/50ml 3.5. Adsorption Isothrms Adsorption isothrm 4-8 dscribs th rlation btwn th amount or concntration of adsorbat that accumulats on th adsorbnt and th quilibrium concntration of th dissolvd adsorbat. Equilibrium studis wr carrid out by agitating a sris of bakrs containing 50 ml of Ni (II) solutions of initial concntration 20 mg/l with g of activatd nano carbon at 30 0 C with a constant agitation. Agitation was providd for 1.0 h, which is mor than sufficint tim to rach quilibrium Frundlich Adsorption Isothrm Th Frundlich adsorption isothrm is basd on th quilibrium sorption on htrognous surfacs. This isothrm is drivd from th assumption that th adsorption sits ar distributd xponntially with rspct to hat of adsorption. Th adsorption isothrm is xprssd by th following quation 1/nF q =KFC Which, can b linarizd as 1 ln q =lnk + lnc F n F (4) Whr, q is th amount of Ni(II) adsorbd at quilibrium (mg/g) and C is th concntration of Ni(II) in th aquous phas at quilibrium (ppm). K F (L/g) and 1/n F ar th Frundlich constants rlatd to adsorption capacity and sorption intnsity, rspctivly. Th Frundlich constants K F and 1/n F wr calculatd from th slop and intrcpt of th lnq Vs lnc plot, th modl paramtrs ar shown in Tabl 2. Th magnitud of K F showd that APANC had a Intrnational Journal of Advancd Rsarch in Chmical Scinc (IJARCS) Pag 4 (3)

5 Isothrm Analysis on th Rmoval of Ni (II) ION from Wastwatr using APANC high capacity for Ni(II) adsorption from th aquous solutions studid. Th Frundlich xponnt, n F, should hav valus in th rang of 1 and 10 (i.., 1/n F < 1) to b considrd as favourabl adsorption 9. A 1/n F valu of lss than 1 indicatd that Ni(II) is favorably adsorbd by APANC. Th Frundlich isothrm did not show a good fit to th xprimntal data as indicatd by SSE and Chi-squar statistics. Tabl1. Equilibrium Paramtrs for th Adsorption of Nickl Ion onto APANC M0M 0 M C (Mg / L)g / L) Q (Mg / L)/ L) Rmoval %Rmoval % 30 o C 40 o C 50 o C 60 o C 30 o C 40 o C 50 o C 60 o C 30 o C 40 o C 50 o C 60 o C Tabl2. Langmuir and Frundlich Isothrm Paramtr for th Adsorption of Nickl Ion onto APANC Tmp. Lan Langmuir Paramtrs Frundlich Paramtrs Tmp. (oc) ( o Q m b K f n 30 o C o C o C o C Langmuir Adsorption Isothrm Th Langmuir adsorption isothrm is basd on th assumption that all sorption sits possss qual affinity to th adsorbat. Th Langmuir isothrm 10 in a linar form can b rprsntd as: C 1 C = + q q K q m L m Whr q is th amount of Ni(II) adsorbd at quilibrium (mg/g), C is th concntration of Ni(II) in th aquous phas at quilibrium (ppm), q m is th maximum Ni(II) uptak (mg/g), and K L is th Langmuir constant rlatd to adsorption capacity and th nrgy of adsorption (g/mg). A linar plot of C /q Vs C was mployd to dtrmin th valu of q m and K L, th data so obtaind wr also prsntd in Tabl 2. Th modl prdictd a maximum valu that could not b rachd in th xprimnts. Th valu of K L dcrasd with an incras in th tmpratur. A high K L valu indicats a high adsorption affinity. Wbr and Chakraborti xprssd th Langmuir isothrm in trm of dimnsionlss constant sparation factor or quilibrium paramtr (R L ) dfind in th following quation: 1 R = (6) 1+K C L L 0 Whr, C 0 is th initial Ni(II) concntration (ppm). Four scnarios can b distinguishd: Th sorption isothrm is unfavorabl whn R L > 1, th isothrm is linar whn R L = 1, Th isothrm is favorabl whn 0 < R L < 1 and th isothrm is irrvrsibl whn R L = 0. Th valus of dimnsionlss sparation factor (R L ) for Ni(II) rmoval wr calculatd at diffrnt concntrations and tmpraturs. As shown in Tabl 3, at all concntrations and tmpraturs tstd th valus of R L for Ni(II) adsorptions on th APANC wr lss than 1 and gratr than zro, indicating favorabl adsorption. Th Langmuir isothrm showd a bttr fit to th adsorption data than th Frundlich isothrm. Th fact that th Langmuir isothrm fits th xprimntal data wll may b du to homognous distribution of activ sits on th APANC surfac, sinc th Langmuir quation assums that th adsorbnt surfac is nrgtically homognous. Intrnational Journal of Advancd Rsarch in Chmical Scinc (IJARCS) Pag 5 (5)

6 S Arivoli & A Arasakumar Tabl3. Dimnsionlss Spration Factor (R l ) for th Adsorption of Nickl Ion onto APANC (Ci) (C Tmpratur C Tmpratur C 30 o C 40 o C 50 o C 60 o C Tmkin Adsorption Isothrm Th Tmkin adsorption isothrm assums that th hat of adsorption dcrass linarly with th sorption covrag du to adsorbnt-adsorbat intractions 11 Th Tmkin isothrm quation is givn as: RT q = ln(k C ) bt T Which, can b rprsntd in th following linar form RT RT q = lnk + lnc b T b Whr, K T (L/g) is th Tmkin isothrm constant, b T (J/mol) is a constant rlatd to hat of sorption, R is th idal gas constant (8.314 J/mol K), and T is absolut tmpratur (K). A plot of q vrsus lnc nabls th dtrmination of isothrm constants K T and b T from th slop and intrcpt, Th modl paramtrs ar listd in Tabl 2. Th Tmkin isothrm appars to provid a good fit to th Ni(II) adsorption data. Th adsorption nrgy in th Tmkin modl, b T, is positiv for Ni(II) adsorption from th aquous solution, which indicats that th adsorption is ndothrmic. Th xprimntal quilibrium curv is clos to that prdictd by Tmkin modl. Consquntly, th adsorption isothrm of Ni(II) on APANC can b dscribd rasonably wll by th Tmkin isothrm Hurkins-Jura Adsorption Isothrm Th Hurkins-Jura 12 adsorption isothrm can b xprssd as: (7) (8) A q = H B H+logC This can rarrangd as follows: (9) 1 BH 1 = - logc 2 AH AH q (10) Whr, A H (g 2 /L) and B H (mg 2 /L) ar two paramtrs charactrizing th sorption quilibrium. Th isothrm quation accounts for multilayr adsorption and can b xplaind by th xistnc of a htrognous por distribution. Th Harkins Jura isothrm paramtrs ar obtaind from th plots of of 1/q 2 vrsus log C nabls th dtrmination of modl paramtrs A H and B H from th slop and intrcpt Halsay Adsorption Isothrm Th Halsay 13 adsorption isothrm can b givn as lnkha -lnc q =xp nha And, a linar form of th isothrm can b xprssd as follows: lnkha lnc lnq = - nha nha Whr, K Ha (mg/l) and n Ha ar th Halsay isothrm constants. (11) (12) Intrnational Journal of Advancd Rsarch in Chmical Scinc (IJARCS) Pag 6

7 Isothrm Analysis on th Rmoval of Ni (II) ION from Wastwatr using APANC A plot of lnq Vs lnc, nabls th dtrmination of n Ha and K Ha from th slop and intrcpt. This quation is suitabl for multilayr adsorption and th fitting of th xprimntal data to this quation attst to th htroporous natur of adsorbnt. Th xprimntal data and th modl prdictions basd on th non-linar form of th Halsay modls. Th modl paramtrs ar listd in Tabl 2. This rsult also shows that th adsorption of Ni(II) on APANC was not basd on significant multilayr adsorption. Th Halsay modl is also not suitabl to dscrib th adsorption of Ni(II) on APANC, bcaus this modl also assums a multilayr bhavior for th adsorption of adsorbat onto adsorbnt Radlich-Ptrson Adsorption Isothrm Th Radlich-Ptrson 14 adsorption isothrm contains thr paramtrs and incorporats th faturs of Langmuir and Frundlich isothrms into a singl quation. Th gnral isothrm quation can b dscribd as follows: q = KRC g 1+aRC Th linar form of th isothrm can b xprssd as follows: (13) C ln =glnc -lnk R q (14) Whr, K R (L/g) and a R (L/mg) ar th Radlich-Ptrson isothrm constants and g is th xponnt btwn 0 and 1. Thr ar two limiting cass: Langmuir form for g = 1 and Hnry s law for g = 0. A plot of ln C /q vrsus ln C nabls th dtrmination of isothrm constants g and K R from th slop and intrcpt. Th valus of K R, prsntd in Tabl 2, indicat that th adsorption capacity of th APANC dcrasd with an incras tmpratur. Furthrmor, th valu of g lis btwn 0 and 1, indicating favorabl adsorption Dubinin-Radushkvich Adsorption Isothrm Th Dubinin-Radushkvich 15 adsorption isothrm is anothr isothrm quation [32]. It is assumd that th charactristic of th sorption curv is rlatd to th porosity of th adsorbnt. Th linar form of th isothrm can b xprssd as follows: 2 1 lnq =lnq -B RTln 1+ D D C Whr, Q D is th maximum sorption capacity (mol/g), and B D is th Dubinin-Radushkvich constant (mol 2 /kj 2 ). A plot of lnq Vs R T ln(1+1/c ) nabls th dtrmination of isothrm constants B D and Q D from th slop and intrcpt Jovanovic Adsorption Isothrm Th modl of an adsorption surfac considrd by Jovanovic 16 is ssntially th sam as that considrd by Langmuir. Th Jovanovic modl lads to th following rlationship [29]: KC J q =qmax 1- (16) Th linar form of th isothrm can b xprssd as follows: lnq = lnq max -K JC (17) Whr, K J (L/g) is a paramtr. q max (mg/g) is th maximum Ni(II) (II) uptak. Th q max is obtaind from a plot of ln q and C, Thir rlatd paramtrs ar listd in Tabl 2. By comparing th valus of th rror functions, it was found th Langmuir and Tmkin modls ar bst to fit th Ni(II) adsorption on th AASCA. Both modls show a high dgr of corrlation. Confirming th good fit of Langmuir and Tmkin modls with th xprimntal data for rmoval of Ni(II) from th solution Th Brunaur Emmtt Tllr (BET) Isothrm Modl Brunaur Emmtt Tllr (BET) 17 isothrm is a thortical quation, most widly applid in th gas solid quilibrium systms. It was dvlopd to driv multilayr adsorption systms with rlativ Intrnational Journal of Advancd Rsarch in Chmical Scinc (IJARCS) Pag 7 (15)

8 S Arivoli & A Arasakumar prssur rangs from 0.05 to 0.30 corrsponding to a monolayr covrag lying btwn 0.50 and Its xtinction modl rlatd to liquid solid intrfac is xhibitd as: qscbetc q = (Cs -C )[1+(CBET -1)(C /C s )] Whr, CBET, Cs, qs and q ar th BET adsorption isothrm (L/mg), adsorbat monolayr saturation concntration (mg/l), thortical isothrm saturation capacity (mg/g) and quilibrium adsorption capacity (mg/g), rspctivly. As C BET and C BET (C /C s ) is much gratr than 1, In th linar form as usd is rprsntd as C 1 C BET -1 = + C q C -C qsc s BET qsc BET C s Whr, C is quilibrium Concntration (mg/l), C s is adsorbat monolayr saturation concntration (mg/l) and C BET is BET adsorption rlating to th nrgy of surfac intraction (l/mg) th BET modl Kintic Paramtrs Th rat and mchanism of th adsorption procss can b lucidatd basd on kintic studis. Ni(II) adsorption on solid surfac may b xplaind by two distinct mchanisms: (1) An initial rapid binding of Ni(II) molculs on th adsorbnt surfac; (2) rlativly slow intra-particl diffusion. To analyz th adsorption kintics of th Ni(II), th psudo-first-ordr, th psudo-scond-ordr, and intraparticl diffusion modls wr applid 18. Each of ths modls and thir linar mods of thm quations prsntd in blow. Kintic Modls and Thir Linar Forms Modl Nonlinar Form Linar Form Numbr of Equation Psudo-first-ordr dq t /d t = k 1 (q -q t ) ln (q -q t ) = ln q -k 1 t (20) Psudo-scond-ordr dq t /d t = k 2 (q -q t ) 2 t/q t = 1/k 2 q 2 + (1/q )t (21) Whr, q and q t rfr to th amount of Ni (II) adsorbd (mg/g) at quilibrium and at any tim, t (min), rspctivly and k 1 (1/min), k 2 (g/mg.min) ar th quilibrium rat constants of psudo-first ordr and psudo-scond ordr modls, rspctivly. Psudo-first ordr modl is a simpl kintic modl, which was proposd by Lagrgrn during 1898 and is usd for stimation of th surfac adsorption raction rat. Th valus of ln (q - q t ) wr linarly corrlatd with t. Th plot of ln (q - q t ) Vs t should giv a linar rlationship from which th valus of k 1 wr dtrmind from th slop of th plot. In many cass, th first-ordr quation of Lagrgrn dos not fit wll with th ntir rang of contact tim and is gnrally applicabl ovr th initial stag of th adsorption procsss. In th psudo-scond ordr modl, th slop and intrcpt of th t/qt Vs t plot wr usd to calculat th scond-ordr rat constant, k 2. Th valus of quilibrium rat constant (k 2 ) ar prsntd in Tabl 5. According to Tabl 5, th valu of R 2 (0.999) rlatd to th psudo-scond ordr modl rvald that Ni(II) adsorption followd this modl, which is in agrmnt with th rsults obtaind by Karagoz t al. 19 Hamd t al. 20. Nvrthlss, psudo-first ordr and psudo-scond ordr kintic modls cannot idntify th mchanism of diffusion of Ni(II) into th adsorbnt pors Simpl Elovich Modl Th simpl Elovich modl 21 is xprssd in th form, q t = α + β ln t Whr, q t is th amount adsorbd at tim t, α and β ar th constants obtaind from th xprimnt. A plot of q t Vs lnt should giv a linar rlationship for th applicability of th simpl Elovich kintic. Th Elovich kintics of Ni(II) on to APANC for various initial concntrations (10, 20, 30, 40 and 50 mg/l) of volum 50 ml (ach), adsorbnt dos 0.025g, tmpratur 30 o C and ph Th Elovich Equation Th Elovich modl quation is gnrally xprssd as dq t / d t = α xp (-βq t ) (23) Intrnational Journal of Advancd Rsarch in Chmical Scinc (IJARCS) Pag 8 (18) (19) (22)

9 Isothrm Analysis on th Rmoval of Ni (II) ION from Wastwatr using APANC Whr; α is th initial adsorption rat (mg g -1 min -1 ) and β is th dsorption constant (g/mg) during any on xprimnt. To simplify th Elovich quation. Chin and Clayton (1980) assumd t>>t and by applying boundary conditions q t = 0 at t= 0 and q t = q t at t = t Eq.(23) bcoms: q t = 1/ ln ( ) + 1/ ln t (24) If Ni (II) ions adsorption fits with th Elovich modl, a plot of q t vs. ln(t) should yild a linar rlationship with a slop of (1/β)and an intrcpt of (1/β)ln (αβ). Th Elovich modl paramtrs α, β, and corrlation cofficint ( ) ar summarizd in tabl 5. Th xprimntal data such as th initial adsorption rat ( ) adsorption constant (β) and th corrlation co-fficint (γ) calculatd from this modl indicats that th initial adsorption (α) incrass with tmpratur similar to that of initial adsorption rat (h) in psudo-scond ordr kintics modls. This may b du to incras th por or activ sit on th APANC adsorbnt Th Intraparticl Diffusion Modl Th kintic rsults wr analyzd by th Intraparticl diffusion modl 22 to lucidat th diffusion mchanism. Th modl is xprssd as: q t = K id t 1/ 2 + I (25) Whr, I is th intrcpt and K id is th intra-particl diffusion rat constant. Th intrcpt of th plot rflcts th boundary layr ffct. Largr th intrcpt, gratr is th contribution of th surfac sorption in th rat controlling stp. Th calculatd diffusion cofficint K id valus ar listd in Tabl 6. Th K id valu was highr at th highr concntrations. Intraparticl diffusion is th sol ratlimiting stp if th rgrssion of q t vrsus t 1/2 is linar and passs through th origin. In fact, th linar plots at ach concntration did not pass through th origin. This dviation from th origin is du to th diffrnc in th rat of mass transfr in th initial and final stags of th sorption. This indicatd th xistnc of som boundary layr ffct and furthr showd that Intraparticl diffusion was not th only rat-limiting stp. It is clar from th Tabl 6 that th psudo- scond-ordr kintic modl showd xcllnt linarity with high corrlation cofficint (R 2 >0.99) at all th studid concntrations in comparison to th othr kintic modls. In addition th calculatd q valus also agr with th xprimntal data in th cas of psudo-scond-ordr kintic modl. It is also vidnt from Tabl 5 that th valus of th rat constant k 2 dcras with incrasing initial Ni(II) concntrations. This is du to th lowr comptition for th surfac activ sits at lowr concntration but at highr concntration th comptition for th surfac activ sits will b high and consquntly lowr sorption rats ar obtaind Thrmodynamic Tratmnt of th Adsorption Procss Thrmodynamic paramtrs associatd with th adsorption, via standard fr nrgy chang ( G 0 ), standard nthalpy chang ( H 0 ), and standard ntropy chang ( S 0 ) wr calculatd as follows. Th fr nrgy of adsorption procss considring th adsorption quilibrium constant K 0 is givn by th quation G = -RT ln K 0 (26) Whr, G is th fr nrgy of adsorption (kj/mol), T is th tmpratur in Klvin and R is th univrsal gas constant(8.314 J mol/k).th adsorption distribution cofficint K 0 for th sorption raction was dtrmind from th slop of th plot of ln(q /C ) against C at diffrnt tmpratur and xtrapolating to zro C according to th mthod suggstd by Khan and Singh[16] Th adsorption distribution cofficint may b xprssd in trms of nthalpy chang ( H ) and ntropy chang ( S ) as a function of tmpratur, ln K o = ( H o /RT)+( S o /R) (27) Whr, H is th standard hat chang of sorption (kj/mol) and S is standard ntropy chang (kj/mol). Th valu of H and S can b obtaind from th slop and intrcpt of plot of ln K 0 against 1/T. Th valu of thrmodynamic paramtr calculatd from quation 26 and 10 ar shown in tabl 4. Th thrmodynamic tratmnt of th sorption data indicats that G valus wr ngativ at all tmpratur. Th rsults point out that physisorption is much mor favorabl for th adsorption of Ni (II) ions. Th positiv valus of H show th ndothrmic natur of adsorption and it govrns th Intrnational Journal of Advancd Rsarch in Chmical Scinc (IJARCS) Pag 9

10 S Arivoli & A Arasakumar possibility of physical adsorption [17]. Bcaus in th cas of physical adsorption, whil incrasing th tmpratur of th systm, th xtnt of mtal ion adsorption incrass, this ruls out th possibility of chmisorptions. Th low H valu dpicts mtal ion is physisorbd onto adsorbnt APANC. Th ngativ G valus tabl 4 wr conform th spontanous natur of adsorption Ni (II) ions onto APANC. Th lssr valus of G suggst that adsorption is physical adsorption procss. Th positiv valus of S in tabl 4, showd incrasd randomnss of th solid solution intrfac during th adsorption of nickl ion onto activatd plastrs Paris. In ordr to support that physical adsorption is th prdominant mchanism, th valus of activation nrgy (Ea) and sticking probability (S*) wr calculatd from th xprimntal data. Thy wr calculatd using modifid Arrhnius typ quation rlatd to surfac covrag (θ) as follows: = C 1- C i Ea S* (1 ) (29) RT Th sticking probability, S*, is a function of th adsorbat/adsorbnt systm undr considration but must satisfy th condition 0 < S*< 1 and is dpndnt on th tmpratur of th systm. Th valus of Ea and S* can b calculatd from slop and intrcpt of th plot of ln(1-θ) vrsus 1/T rspctivly (As shown in Fig. 17) and ar listd in Tabl 4. Tabl4. Thrmodynamic Paramtr for th Adsorption of Nickl Ion onto APANC ((C0)C 0 ) Go G o H H S S 30 o C 40 o C 50 o C 60 o C Tabl5. Th Kintic Paramtrs for th Adsorption of Nickl Ion onto APANC C0C 0 T Tmp C mp Psud Psudo scond ordr o scond ordr Elovich modl Elovich modl Intra Intraparticl diffusion particl diffusion q K 2 h K id C (28) Intrnational Journal of Advancd Rsarch in Chmical Scinc (IJARCS) Pag 10

11 Isothrm Analysis on th Rmoval of Ni (II) ION from Wastwatr using APANC From Tabl 5 it is clar that th raction is spontanous in natur as ΔG 0 valus ar ngativ at all th tmpratur studid. Again positiv ΔH 0 valu confirms that th sorption is ndothrmic in natur. Th positiv valu of ΔS 0 rflcts th affinitis of th adsorbnts for th Ni(II). Th rsult as shown in Tabl 5 indicat that th probability of th Ni(II) to stick on surfac of biomass is vry high as S*<< 1, ths valus confirm that, th sorption procss is physisorption Dsorption Studis Dsorption studis hlp to lucidat th natur of adsorption and rcycling of th spnt adsorbnt and th mtal ions. If th adsorbd mtal ions can b dsorbd using nutral ph watr, thn th attachmnt of th mtal ion of th adsorbnt is by wak bonds. Th ffct of various ragnts usd for dsorption studis. Th rsults indicat that hydrochloric acid is a bttr ragnt for dsorption, bcaus w could gt mor than 90% rmoval of adsorbd mtal ion. Th rvrsibility of adsorbd mtal ion in minral acid or bas is in agrmnt with th ph dpndnt rsults obtaind. Th dsorption of mtal ion by minral acids and alkalin mdium indicats that th mtal ion was adsorbd onto th APANC through physisorption as wll as by chmisorptions mchanisms. 4. CONCLUSION APANC prpard from Pandanus Amaryllifolius Stm (Aavaarai) was found ffctiv in rmoving nickl ion from aquous solution. Th adsorption is fastr and th rat is mainly controlld by intraparticl diffusion. Using th sorption quation obtaind from th Langmuir and Frundlich isothrms, it was found that APANC is an ffctiv on for th rmoval of nickl ion. Th quilibrium data conformd wll to th Langmuir and BET isothrm modls. Th tmpratur variation study showd that th nickl ion adsorption is ndothrmic and spontanous with incrasd randomnss at th solid solution intrfac. Significant ffct on adsorption was obsrvd on varying th ph of th nickl ion solution. ph dpndnt rsults and dsorption of mtal ion in minral acid suggst that th adsorption of mtal ion on APANC involvs chmisorptions as wll as physisorption mchanism. REFERENCES [1] Zolfaghari, G., Esmaili-Sari, A., Anbia, M., Younsi, H. and Ghasmian, M.B., A zinc oxidcoatd nanoporous carbon adsorbnt for lad rmoval from watr: Optimization, quilibrium modling, and kintics studis, (2013). Intrnational Journal of Environmntal Scinc and Tchnology, 10 (2), [2] Mmarian, R. and Ramamurthy, A.S., Modling of lad and cadmium uptak by plants in th prsnc of surfactants, (2013), Environmntal Monitoring and Assssmnt, 185 (3), [3] Vijayaraghavan, K. and Joshi, U.M., Chickn Eggshlls Rmov Pb (II) Ions from Synthtic Wastwatr, (2013), Environmntal Enginring Scinc, 30 (2), [4] Shukla, N.B. and Madras, G., Kintics of adsorption of mthyln blu and rhodamin 6G on acrylic acid-basd suprabsorbnts, (2012), Journal of Applid Polymr Scinc, 126 (2), [5] Usman, A.R.A., Sallam, A.S., Al-Omran, A., El-Naggar, A.H., Alnazi, K.K.H., Nadm, M. and Al-Wabl, M.I., Chmically Modifid Biochar Producd from Conocarpus Wasts: An Efficint Sorbnt for F(II) Rmoval from Acidic Aquous Solutions, (2013), Adsorption Scinc & Tchnology, 31 (7), [6] Diaz, P.V., Mdina, E.C., Nunz, F.U. and Fabila, M.G., Rus of Citrullus Lanatus Pl As Biosorbnt to Rmov Aluminum in Aquous Phas, (2013), Frsnius Environmntal Bulltin, 22 (5), [7] Bulgariu, L., Lupa, M., Bulgariu, D., Rusu, C. and Macovanu, M., Equilibrium Study of Pb(Ii) and Cd(Ii) Biosorption from Aquous Solution on Marin Grn Alga Biomass, (2013), Environmntal Enginring and Managmnt Journal, 12 (1), [8] Duran-Blanco, J.M., Lopz-Munoz, B.E. and Olguin, M.T., Influnc of ph on U(VI) Adsorption using a Thrmally-Tratd Mg-Al Hydrotalcit and a Natural Zolit in a Batch Systm, (2013), Sparation Scinc and Tchnology, 48 (5), [9] Vistuba, J.P., Nagl-Hassmr, M.E., Lapolli, F.R. and Rcio, M.A.L., Simultanous adsorption of iron and mangans from aquous solutions mploying an adsorbnt coal, (2013), Environmntal Tchnology, 34 (2), Intrnational Journal of Advancd Rsarch in Chmical Scinc (IJARCS) Pag 11

12 S Arivoli & A Arasakumar [10] Frndlich H, Th dy adsorption is losungn (Adsorption in Solution), (1906), Z Phys. Chm.,57, [11] Taghdiri, M. and Zamani, N., Hxamin adsorption study on activatd carbon from aquous solutions for application in tratmnt of hxamin industrial wastwatr, (2013), Intrnational Journal of Environmntal Scinc and Tchnology, 10 (1), [12] Bulgariu, L., Hlihor, R.M., Bulgariu, D. and Gavrilscu, M., Sorptiv Rmoval of Cadmium (Ii) Ions from Aquous Solution by Mustard Biomass, (2012), Environmntal Enginring and Managmnt Journal, 11 (11), [13] Hadi, M., Mckay, G., Samarghandi, M.R., Malki, A. and Aminabad, M.S., Prdiction of optimum adsorption isothrm: comparison of chi-squar and Log-liklihood statistics, (2012), Dsalination and Watr Tratmnt, 49 (1-3), [14] Langmuir I, Th adsorption of gass plan surfacs of glass, mica and platinum, (1918), J. Am. Soc., 579, [15] Hang, X.F., Xu, Y.M., Wang, L., Sun, Y.B., Lin, D.S., Sun, Y., Qin, X. and Wan, Q., Sorption of Pb2+ on mrcapto functionalizd spiolit, (2013), Chmosphr, 90 (2), [16] Zhou, Y.N., Wang, Z., Zhang, Q., Xi, X.J., Zhang, J. and Yang, W.T., Equilibrium and thrmodynamic studis on adsorption of BSA using PVDF microfiltration mmbran, (2012), Dsalination, 307, [17] Khan, A A, Singh, R P. Adsorption thrmodynamics of carbofuran on Sn (IV) arsnosilicat in H +, Na + and Ca 2+ forms, (1987), Colloid & Surfacs (24) [18] Ghosh, A. and Das Saha, P., Optimization of Ni(II) adsorption by chmically modifid fly ash using rspons surfac mthodology modling, (2012), Dsalination and Watr Tratmnt, 49 (1-3), [19] Chin S H. and Clayton.W R, Application of Elovich Equation to th kintics of Phosphat rlas and sorption on soil, (1980), Soil Sci. Sco. Am, J., 44, [20] W. J. Wbr and Morris J C., Kintics of adsorption on Carbon from solution, (1964), J. Sanitary Engg. Div. 90, 79. Intrnational Journal of Advancd Rsarch in Chmical Scinc (IJARCS) Pag 12