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1 Intrnational Journal of Latst Rsarch in Scinc and Tchnology Volum 6, Issu 1: Pag No.32-40,January-Fbruary ISSN (Onlin): ISOTHERM ANALYSIS ON THE REMOVAL OF RHODAMINE B DYE FROM ARTIFIIAL WASTEWATER USING NANO-POROUS ARBON 1 A Arasakumar, 2 S Arivoli*, 3 V Marimuthu 1 Rsarch Scholar, Dpartmnt of hmistry, Thiru Vi Ka Govrnmnt Arts ollg, Thiruvarur, Tamilnadu, India 2 Associat Profssor and Had, Dpartmnt of hmistry, Thiru Vi Ka Govrnmnt Arts ollg, Thiruvarur, Tamilnadu, India 3 Gust Lcturr, Dpartmnt of hmistry, Dpartmnt of hmistry, Thiru Vi Ka Govrnmnt Arts ollg, Thiruvarur, Tamilnadu, India Abstract Application of Pandanus Amaryllifolius Stm for th rmoval of a ationic dy, Rhodamin B, from auous solutions has bn invstigatd. Th xprimnts wr carrid out in batch mod. Effct of th paramtrs such as ph, initial dy concntration and tmpratur on th rmoval of th dy was studid. Euilibrium was achivd in 60 min. Maximum adsorption of dy was achivd at ph 6.7. Rmoval prcntag was found to b dpndnt on th initial concntration of dy solution, and maximum rmoval was found to b 97% at 25 mg/l of Rhodamin B. Th rmoval incrass from 83% to 97% whn th initial concntration of dy solution dcrass from 125 mg/l to 50 mg/l. Th uilibrium adsorption data wr analyzd by Langmuir, Frundlich, Tmkin and Dubinin Radushkvich isothrm modls. Th (Langmuir) adsorption capacity of th adsorbnt is found to b mg/g at 303 K. Kintic modling of th procss of rmoval was carrid out and th procss of rmoval was found to follow a psudo scond ordr modl. Th thrmodynamic paramtrs such as chang in fr nrgy (ÄG 0 ), nthalpy (ÄH 0 ) and ntropy (ÄS 0 ) wr dtrmind and th ngativ valus of ÄG 0 indicatd that th procss of rmoval was spontanous at all valus of tmpraturs. Furthr, th valus of ÄH 0 indicatd th ndothrmic natur of th procss of rmoval. Kywords -Activatd Pandanus Amaryllifolius Stm Nano arbon (APAN); Rhodamin-B dy; Adsorption isothrm; Kintics; Euilibrium modls I. INTRODUTION With th rvolution in txtil industris discharg colourd fflunts such as organic dys lik Mthyln Blu and Rhodamin-B to watr bodis. Ths colourd fflunts hav larg amounts of suspndd organic solids which ar harmful to human bings and toxic for organisms. Th rmoval of ths dys from wastwatr has a considrabl attntion ovr th past dcads to dcras thir impact on th nvironmnt [1]. Svral physical and chmical mthods hav bn dvlopd for th rmoval of organic dys from industrial fflunts [2]. Physical mthods, mainly adsorption on various supports wr rcognizd to b a promising and ffctiv procss to rmov dys from industrial wast watrs compltly [3, 4]. Th main advantags of adsorption ar th rusability of matrial, low-cost, as of opration and short tim of opration so it is ncssary to dvlop ffctiv adsorbnts for th rmoval of dys from txtil fflunts. Activatd carbon is th most widly usd adsorbnt and can b prpard by physical activation in which carbonation or pyrolysis of th carbonacous matrial at highr tmpratur ( º) in an inrt atmosphr followd by thrmal activation at th sam tmpratur in th prsnc of oxidizing agnt such as air, stam and carbon dioxid or chmical activation in which pyrolysis and activation carrid out only in on stp simultanously in prsnc of dhydrating agnt such as H 3 PO 4, HNO 3, KOH, NaOH, H2O 2, H2SO 4. hmically activatd carbon has highr yild, mor surfac ara and bttr dvlopmnt of porous structur than that obtaind by physical activation [5]. Svral attmpts hav bn studid for th prparation of activatd carbon from agricultur wasts. In this articl, w hav rportd th us of natural bio matrials is an altrnativ du to thir rlativ abundanc and thir low commrcial valus. Pandanus Amaryllifolius Stm is th most ancint plant of India. It is found throughout India, spcially in Tamil Nadu, Krala, Bngal and solv south rgion, th arial parts of th tr hav mdicinal valus and this work studid th possibility of using falln Shll of a Pandanus Amaryllifolius Stm plant as an adsorbnt for th adsorption of cationic dy Rhodamin-B from auous solution. A survy of litratur shows that no work has bn don so for a vitalization of falln Acacia Nilotica plant Shll as an adsorbnt. II. MATERIALS & METHODS All ragnts usd in th xprimnts wr of analytical (AR) grad and wr obtaind from scintific uipmnt company Trichy. Stock solutions of th tst ragnts wr prpard by dissolving th dy in distilld watr. 2.1 Prparation of adsorbnt Th natural plant matrial for Pandanus Amaryllifolius Stm usd in th prsnt invstigations was collctd from a narby Thiruvarur ara. Th lav was washd with distilld watr svral tims to rmov th dirt and dust and was subsuntly drid in a hot air ovn at 110 o. Aftrward, carbonization of th Shll was carrid out by adding w/v ratio on.h 2 SO 4 to gt th primary carbon. Th primary carbon ISSN:

2 was activatd at for 6 hrs undr optimizd conditions to obtain th activatd nano carbon. Intrnational Journal of Latst Rsarch in Scinc and Tchnology. Amaryllifolius Stm, rspctivly. X-ray spctra of both adsorbnts do not show any pak indicating th amorphous natur of activatd Pandanus Amaryllifolius Stm nano carbon. Tabl 1-haractristics of th Adsorbnt 2.2 Exprimntal Procdur Batch xprimnts wr conductd to study th influnc of important paramtrs lik th ph, contact tim, initial dy concntration and tmpratur on th rmoval of Rh-B onto activatd Pandanus Amaryllifolius Stm Nano arbon. For Adsorption Isothrms, dy solution of diffrnt concntrations ( mg/l) and at diffrnt tmpraturs (30-60 º) with known ph and known amount of adsorbnt (25 mg/l) wr agitatd at 120 rpm until th uilibrium was rachd thn th solution was kpt to sttl down and th rsidual concntration of Rh-B wr analysd by UV-Visibl spctrophotomtr at 554 nm. All xprimnts wr carrid out at normal ph for Rh-B. Effct of ph on dy rmoval was studid ovr a ph rang of th initial ph of th solution was adjustd by addition of actat or phosphat buffrs. Th ffct of sorbnt dosag on adsorption rat was invstigatd using th procdurs dscribd abov xcpt that diffrnt dosags ( mg/50ml) wr usd. Th prcntag of dy rmoval was calculatd using th following uation. (i) ( t) x v ( t ).. (1) m Whr, (t) is th mass of adsorbd dy pr unit mass of adsorbnt (mg g -1 ) (i) and (t) ar th initial and actual concntration (g dm -3 ) of dy at tim, rspctivly V is th volum of th tratd solution (ml) m is th mass of adsorbnt (g) Th adsorption dgr, AD as a function of tim was also dtrmind from th xprimntal data using th following rlationship. 1 - ( t ) X A D % = i.. (2) Basd on th adsorption kintics xprimnts, th procss tim for th uilibrium adsorption xprimnts was chosn, long nough assuming that th considrd sorbnt / sorbat systm is uilibratd. Th following paramtrs of th procss wr changd during ths xprimnts kind and amount of adsorbnt (Activatd Pandanus Amaryllifolius Stm) th particl siz: Th initial ph of th solutions and th initial concntration of th considrd ions, all xprimnts wr prformd at ambint tmpratur. III. RESULT AND DISUSSION 3.1 haractrization Th diffrnt chmical constitunts of activatd Pandanus Amaryllifolius Stm Nano arbon ar givn in Tabl 1 along with som othr charactristics. Surfac ara of th sampls activatd in air is 527 and 96 m 2 g -1 for Activatd Pandanus Proprtis 3.2 Effct of ontact tim APAN Particl siz(mm) Dnsity (g/cc) Moistur contnt (%) Loss in ignition (%) ph of auous solution In ordr to stablish th uilibration tim for maximum uptak and to know th kintics of th adsorption procss, Rh-B adsorption on APAN adsorbnt was invstigatd as a function of contact tim and th rsults wr shown in fig 1. Th figur shows that th uptak rat was initially rapid with 50% of th adsorption was complt with in 30 min, Euilibrium was achivd with in 50 min thrfor, an uilibration priod of 1 h was slctd for all furthr xprimnts. Th tim profil of RhB uptak is a singl Smooth and continuous curv lading to saturation suggsting th possibl monolayr covrag of Rh-B on th surfac of th adsorbnt. 3.3 Effct of adsorbnt dosag Th adsorption of th Rh-B dy on APAN was studid by varying th adsorbnt dos ( mg/50ml) for 50 mg/l of dy concntration. Th prcntag of adsorption incrasd with incrass in th APAN dos, which is attributd to incrasd carbon surfac ara and th availability of mor adsorption sits [6, 7]. Hnc, all studis wr carrid out with 0.025g of adsorbnt/50 ml of th varying adsorbat solutions.25, 50, 75, 100 and 125 mg/l. Th rsults obtaind from this study ar shown in figur 2. Th amount of Rh-B adsorbd pr gram rducd with incras in th dosag of APAN. This rvals that th dirct and uilibrium capacitis of Rh-B ar functions of th activatd APAN dosag. 3.4 Effct of Initial ph Prvious rsarch [8] has shown that th adsorption of dy molculs onto an adsorbnt is highly ph dpndnt sinc, th functional groups, which ar rsponsibl for intraction btwn dy molculs and adsorbnt, can b protonatd or dprotonatd to produc diffrnt surfac chargs in solution at diffrnt ph valus. Thrfor th ffcts of initial solution ph wr studid in th ph rang of 2-9 for Rh-B. Th prcntag rmoval incrasd from 63 % to 92 % for Rh-B whras it dcrasd slowly aftr ph 8 for Rh-B (Fig 3). Th ph zpc of any adsorbnt is a vry important charactristic that dtrmins th ph at which th surfac has nt lctrical nutrality. It is wll-known that for basic dy adsorption, ngativly chargd groups on th adsorbnt ar ncssary. At lowr ph valus (ph < ph zpc ) th surfac charg of th surfac of APAN may gt positivly chargd as a rsult of bing surroundd by H 3 O + ions and thus th comptitiv ffcts of H 3 O + ions as wll as th lctrostatic rpulsion btwn th dy molculs and th positivly ISSN:

3 chargd activ adsorption sits on th surfac of th APAN lad to a dcras in th uptak of dy molculs. In contrast at highr ph valus (ph > ph zpc ) th surfac of APAN may acuir a ngativ charg lading to an incras in dy uptak du to th lctrostatic forc of attraction. On th othr hand no valid rason can b givn for th dcras in th adsorption amount of RhB aftr ph 8. Similar rsults wr obtaind for th adsorption of Rhodamin-B onto Activatd Pandanus Amaryllifolius Stm. As a rsult, th initial ph valu was optimizd as 7.0 for dy. 3.5 Effct of othr ions Th ffct of othr ions lik a 2+ and l - on th adsorption procss studid at diffrnt concntrations. Th ions addd to 50mg/L of Rh-B solutions and th contnts wr agitatd for 60 min at 30 o. Th rsults had shown in th Fig. 4 rvals that low concntration of l - dos not affct th prcntag of adsorption of Rh-B on APAN, bcaus th intraction of l - at availabl sits of adsorbnt through comptitiv adsorption is not so ffctiv. Whil th concntration of othr ion a 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 a 2+ compard with l - 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 [9]. 3.6 Adsorption Modls Adsorption isothrm [10] dscribs th rlation btwn th amount or concntration of adsorbat that accumulats on th adsorbnt and th uilibrium concntration of th dissolvd adsorbat. Euilibrium studis wr carrid out by agitating a sris of bakrs containing 100 ml of Rhodamin B (MG) dy solutions of initial concntration 25 mg/l with g of activatd nano carbon at 30 0 with a constant agitation. Agitation was providd for 1.0 h, which is mor than sufficint tim to rach uilibrium. Formula usd for calculation of is as follows: m 0 V Intrnational Journal of Latst Rsarch in Scinc and Tchnology... (3) Frundlich adsorption isothrm Th Frundlich adsorption isothrm is basd on th uilibrium 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 uation. 1/nF =K F (3) Which, can b linarizd as 1 ln =lnk + ln...(4) F nf Whr, is th amount of MG dy adsorbd at uilibrium (mg/g) and is th concntration of MG dy in th auous phas at uilibrium (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 ln Vs ln plot, and th modl paramtrs ar shown in Tabl 3. Th magnitud of K F showd that APAN had a high capacity for RH-B dy adsorption from th auous 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 [11]. A 1/n F valu of lss than 1 indicatd that RH-B dy is favourably adsorbd by APAN. Th Frundlich isothrm did not show a good fit to th xprimntal data as indicatd by SSE and hi-suar statistics Langmuir adsorption isothrm Th Langmuir adsorption isothrm is basd on th assumption that all sorption sits possss ual affinity to th adsorbat. Th Langmuir isothrm in a linar form can b rprsntd as [12]. 1 = + (5) m K L m Whr is th amount of RH-B dy adsorbd at uilibrium (mg/g), is th concntration of RH-B in th auous phas at uilibrium (ppm), m is th maximum RH-B dy 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 / Vs was mployd to dtrmin th valu of m and K L and th data so obtaind wr also prsntd in Tabl 3. 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 hakraborti [13] xprssd th Langmuir isothrm in trm of dimnsionlss constant sparation factor or uilibrium paramtr (R L ) dfind in th following uation: 1 R =.. (6) 1 + K ISSN: L L 0 Whr, 0 is th initial RH-B dy concntration (ppm). Four scnarios can b distinguishd: Th sorption isothrm is unfavourabl 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 RH-B dy rmoval wr calculatd at diffrnt concntrations and tmpraturs. As shown in Tabl 4, at all concntrations and tmpraturs tstd th valus of R L for RH-B dy adsorptions on th APAN wr lss than 1 and gratr than zro, indicating favourabl 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 APAN surfac, sinc th Langmuir uation assums that th adsorbnt surfac is nrgtically homognous Tmkin adsorption isothrm

4 Th Tmkin adsorption isothrm assums that th hat of adsorption dcrass linarly with th sorption covrag du to adsorbnt-adsorbat intractions [14] Th Tmkin isothrm uation is givn as: RT = ln(k )...(7) bt T Which, can b rprsntd in th following linar form RT RT = lnk + ln...(8) 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 vrsus ln nabls th dtrmination of isothrm constants K T and b T from th slop and intrcpt, Th modl paramtrs ar listd in Tabl 3. Th Tmkin isothrm appars to provid a good fit to th RH-B dy adsorption data. Th adsorption nrgy in th Tmkin modl, b T, is positiv for RH-B dy adsorption from th auous solution, which indicats that th adsorption is ndothrmic. Th xprimntal uilibrium curv is clos to that prdictd by Tmkin modl. onsuntly, th adsorption isothrm of RH-B dy on APAN can b dscribd rasonably wll by th Tmkin isothrm Hurkins-Jura adsorption isothrm Th Hurkins-Jura adsorption isothrm can b xprssd as [15] A = H...(9) B H+log This can rarrangd as follows: 1 BH 1 = - log...(10) 2 AH AH Whr, A H (g 2 /L) and B H (mg 2 /L) ar two paramtrs charactrizing th sorption uilibrium. Th isothrm uation 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 1/ 2 vrsus log nabls th dtrmination of modl paramtrs A H and B H from th slop and intrcpt Halsay adsorption isothrm Th Halsay adsorption isothrm can b givn as [16] lnkha -ln =xp...(11) n Ha And, a linar form of th isothrm can b xprssd as follows: lnkha ln ln = -...(12) nha nha Whr, K Ha (mg/l) and n Ha ar th Halsay isothrm constants. A plot of ln Vs ln, nabls th dtrmination of n Ha and K Ha from th slop and intrcpt. This uation is suitabl for multilayr adsorption and th fitting of th xprimntal data to this uation attst to th htroporous natur of adsorbnt. That th xprimntal data and th modl prdictions basd on th non-linar form of th Halsay modls. Th modl paramtrs ar listd in Tabl 3. This Intrnational Journal of Latst Rsarch in Scinc and Tchnology. rsult also shows that th adsorption of RH-B dy on APAN was not basd on significant multilayr adsorption. Th Halsay modl is also not suitabl to dscrib th adsorption of RH-B dy on APAN, bcaus this modl also assums a multilayr bhaviour for th adsorption of adsorbat onto adsorbnt Rdlich-Ptrson adsorption isothrm Th Rdlich-Ptrson adsorption isothrm contains thr paramtrs and incorporats th faturs of Langmuir and Frundlich isothrms into a singl uation. Th gnral isothrm uation can b dscribd as follows [16] K R =...(13) g 1+a R Th linar form of th isothrm can b xprssd as follows: ln =gln -lnk...(14) R 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 / vrsus ln nabls th dtrmination of isothrm constants g and K R from th slop and intrcpt. Th valus of K R, prsntd in Tabl 3, indicat that th adsorption capacity of th APAN dcrasd with an incras tmpratur. Furthrmor, th valu of g lis btwn 0 and 1, indicating favourabl adsorption Dubinin-Radushkvich adsorption isothrm Th Dubinin-Radushkvich adsorption isothrm is anothr isothrm uation. 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 [16]. 2 1 ln =lnq -B RTln 1+...(15) D D 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 ln Vs R T ln(1+1/ ) 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 Jovanovich is ssntially th sam as that considrd by Langmuir. Th Jovanovich modl lads to th following rlationship [17] ISSN: K J = m a x 1 -. (15.1) Th linar form of th isothrm can b xprssd as follows: ln = ln m a x -K J. (15.2) Whr, K J (L/g) is a paramtr. max (mg/g) is th maximum dy uptak. Th max is obtaind from a plot of ln and. Thir rlatd paramtrs ar listd in Tabl 3.

5 By comparing th valus of th rror functions, it was found th Langmuir and Tmkin modls ar bst to fit th RH-B adsorption on th APAN. Both modls show a high dgr of corrlation. onfirming th good fit of Langmuir and Tmkin modls with th xprimntal data for rmoval of RH-B dy from th solution Th Brunaur-Emmtt-Tllr (BET) isothrm modl Brunaur-Emmtt-Tllr (BET) [17] isothrm is a thortical uation, most widly applid in th gas solid uilibrium systms. It was dvlopd to driv multilayr adsorption systms with rlativ concntration rangs from 25 to 125 mg/l corrsponding to a monolayr covrag lying btwn 25 and 75 mg/l. Its xtinction modl rlatd to liuid-solid intrfac is xhibitd as: sbet =...(16) (s - )[1+(BET -1)( / s )] Whr, BET, s, s and ar th BET adsorption isothrm (L/mg), adsorbat monolayr saturation concntration (mg/l), thortical isothrm saturation capacity (mg/g) and uilibrium adsorption capacity (mg/g), rspctivly. As BET and BET ( / s ) is much gratr than 1, In th linar form as usd is rprsntd as 1 BET -1 = +...(17) - s s BET s BET s Whr, is uilibrium oncntration (mg/l), s is adsorbat monolayr saturation concntration (mg/l) and BET is BET adsorption rlating to th nrgy of surfac intraction (l/mg) th BET modl. 3.7 Kintic paramtrs Th rat and mchanism of th adsorption procss can b lucidatd basd on kintic studis. Dy adsorption on solid surfac may b xplaind by two distinct mchanisms: (1) An initial rapid binding of dy molculs on th adsorbnt surfac; (2) rlativly slow intra-particl diffusion. To analyz th adsorption kintics of th dy, th psudo-firstordr, th psudo-scond-ordr, and intra-particl diffusion modls wr applid. Each of ths modls and thir linar mods of thm uations prsntd in blow. ln ( - t) = ln -k 1t (18) t/ t= 1/k (1/ )t (19) Whr, and t rfr to th amount of dy adsorbd (mg/g) at uilibrium and at any tim, t (min), rspctivly and k 1 (1/min), k 2 (g/mg. min) ar th uilibrium 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 [16] during 1898 and is usd for stimation of th surfac adsorption raction rat. Th valus of ln ( - t ) wr linarly corrlatd with t. Th plot of ln ( - 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 uation of Lagrgrn dos not fit wll with th ntir rang of contact tim and is Intrnational Journal of Latst Rsarch in Scinc and Tchnology. gnrally applicabl ovr th initial stag of th adsorption procsss [18]. In th psudo-scond ordr modl, th slop and intrcpt of th t/t Vs t plot wr usd to calculat th scond-ordr rat constant, k 2. Th valus of uilibrium rat constant (k 2 ) ar prsntd in Tabl 6. According to Tabl 6, th valu of R 2 (0.999) rlatd to th psudo-scond ordr modl rvald that (RH-B) dy adsorption followd this modl. Nvrthlss, psudo-first ordr and psudo-scond ordr kintic modls cannot idntify th mchanism of diffusion of dy into th adsorbnt pors Th Elovich uation Th Elovich modl uation is gnrally xprssd as d t / d t = á xp (-â t )..(20) Whr; á is th initial adsorption rat (mg g -1 min -1 ) and â is th dsorption constant (g/mg) during any on xprimnt. To simplify th Elovich uation, hin and layton [18] assumd t>>t and by applying boundary conditions t = 0 at t= 0 and t = t at t = t E. (20) bcoms: t = 1/ ln () + 1/ ln t (21) If Rh-B adsorption fits with th Elovich modl, a plot of t vs ln(t) yilds a linar rlationship with a slop of (1/â)and an intrcpt of (1/â)ln (áâ). Th Elovich modl paramtrs á, â, and corrlation cofficint () ar summarizd in tabl 6. Th xprimntal data such as th initial adsorption rat () adsorption constant (â) and th corrlation co-fficint (ã) calculatd from this modl indicats that th initial adsorption (á) 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 APAN adsorbnt Wbr and Morris intra-particl diffusion modl Kintic data was furthr analyzd using th Intraparticl diffusion modl basd on th thory proposd by Wbr and Morris [19]. Th amount of Rh-B adsorbd ( t ) at tim t was plottd against th suar root of tim (t ½ ), according to. Qt= k id t ½ + (22) Whr, k id is th Intraparticl diffusion rat constant and c is th intrcpt rlatd to th thicknss of th boundary layr. According to abov uation a plot of t vrsus t ½ givs a straight lin from th origin says th adsorption mchanism follows th intra-particl diffusion procss only. Howvr, th data xhibit multi linar plots, says th procss ar govrnd by two or mor stps, It is clar from that thr ar two sparat zons: first linar portion (phas I) and scond linar part (phas II). Th first linar portion (Phas I) can b attributd to th immdiat utilization of th most radily availabl adsorbing sits on th adsorbnt surfac, phas II may b attributd to vry slow diffusion of th adsorbat from th surfac sit in to th innr pors. Thus initial portion of Rh-B adsorption by adsorbnt may b govrnd by th initial intraparticl transport of Rh-B controlld by surfac diffusion procss and th latr part controlld by por diffusion. Howvr, th intrcpt of th lin fails to pass through th origin which may b du to th diffrnc in th rat of mass transfr in th initial and final stags of adsorption. Furthr, such dviation of th straight lins from ISSN:

6 th origin rvals that th por diffusion is not th sol ratcontrolling. 3.8 Thrmodynamic paramtrs Thrmodynamic paramtrs [15] wr valuatd to confirm th adsorption natur of th prsnt study. Th thrmodynamic constants, fr nrgy chang, nthalpy chang and ntropy chang wr calculatd to valuat th thrmodynamic fasibility and th spontanous natur of th procss. Enthalpy chang (ÄH), and ntropy chang (ÄS) may b dtrmind from Van t Hoff uation: S H ln K (23) R R T By plotting ln K as ordinat and 1/T as abscissa, w will gt ÄS, ÄH and by using th following uation. W can gt th valu of hav ÄS, ÄH. And by this uation, gt th valu of ÄG. G H T S (24) Whr, ÄG is th fr nrgy chang (kj mol 1 ), R is th univrsal gas constant (8.314 J mol 1 K 1 ), K th thrmodynamic uilibrium constant and T is th absolut tmpratur (K). G H T S RT ln K (25) S H ln K c (26) R RT S H 2.30 log (27) R R T S H lo g (28) R R T Th valus of ÄS, ÄH, ÄG was obtaind from a plot of log ( / ) vs. 1/T. Hat of raction (-ÄH) for physical adsorption is rportd to b 4.2 to 63 kj/ mol in litratur. Th valu of ÄH which indicat that th natur of adsorption of Rhodamin B dy on APAN is physical adsorption. Th ngativ valu of ÄH & ÄG indicat xothrmic and spontanous procss of adsorption of Rhodamin B dy on APAN rspctivly. 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 uation rlatd to surfac covrag (è) as follows [20]: = 1 -. (29) i E a S * (1 ) (30) R T 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-è) vrsus 1/T rspctivly and ar listd in Tabl 5. From Tabl 5 it is clar that th raction is spontanous in natur as ÄG 0 valus ar ngativ at all th tmpratur studid. Again positiv ÄH 0 valu confirms that th sorption is ndothrmic in natur. Th positiv valu of ÄS 0 rflcts c Intrnational Journal of Latst Rsarch in Scinc and Tchnology. th affinitis of th adsorbnts for th MB dy. Th rsult as shown in Tabl 5 indicat that th probability of th MB dy to stick on surfac of biomass is vry high as S*<< 1, ths valus confirm that, th sorption procss is physisorption. 4. Dsorption studis In ordr to assss th rusability of Rh-B-loadd Activatd Pandanus Amaryllifolius Stm biomass dsorption xprimnts wr carrid out. Th ffct of strngth of dsorbing solution (NaOH) on th rcovry of Rh- B is shown in Figur 5. It is vidnt from th abov figur that whn th strngth of th dsorbing solution incrasd from 0.5 to 2.0 M, Rh-B dsorption prcntag incrasd from 30% to 85%. Thus a significant amount of Rhodamin B is bing dsorbd, which shows that th APAN biomass can b ffctivly rusd aftr dsorption [20]. IV. ONLUSION On th basis of th abov studis, th following can b concludd: I. haractrization of Activatd Pandanus Amaryllifolius Stm was carrid out which rvald that th surfac of th adsorbnt was rough and suitabl for adsorption. II. Pandanus Amaryllifolius Stm Nano arbon has shown a potntial to rmov Rhodamin B from auous solution. III. Initial concntration of th dy plays an important rol in th rmoval procss. IV. Kintics of th procss rmoval was studid and th valus of rat constants wr dtrmind. Th dy rmoval was found to b govrnd by film diffusion mchanism whr xtrnal transport of th adsorbat ovr surfac of th adsorbnt is gratr than intrnal transport which was confirmd by th Boyd plot and th procss of rmoval was found to follow scond ordr kintics. V. Thrmodynamic paramtrs wr calculatd for th rmoval of dy and thir valus indicatd that th procss of rmoval was spontanous and ndothrmic. VI. Th data wr found to bst fittd in D-R isothrm modl. It can thrfor b concludd that Pandanus Amaryllifolius Stm offrs promis as an conomically viabl altrnativ for sustring of th dy from th auous solution. Th work can b xtndd for th rmoval of dys from fflunts as wll. REFERENE 1. Al Duri B. Mckay G. El Gundi, M. S. Wahab Abdul M. Z. Thr Rsistanc Transport Modl for dy Adsorption onto Bagass Pitch. J. Environ. Eng. Div. ASE, 1990,116, S Arivoli M Hma S Parthasarathy and N Manju. Adsorption dynamics of mthyln blu by acid activatd carbon. J. hm. Pharm. Rs, 2010, 2(5), M Hma and S Arivoli, Rhodamin B adsorption by activatd carbon: Kintic and uilibrium studis, Indian Journal of hmical Tchnology, 2009, 16(1), ISSN:

7 4. V Vijayakumaran, S Arivoli and S Ramuthai Adsorption of nickl ion by low cost carbon-kintic, thrmodynamic and uilibrium studis, 2009, 6 (S1), S347-S Alln S. J. Mckay G. Khadr K. Y. H. Intraparticl Diffusions of Basic Dy during Adsorption onto Sphagnum Pat. Environ. Pollut. 1989, 56, Alprt N. L. Ksi W. E. Szymanaki, H. A. Thory and Practic of Infrard Spctroscopy, 2nd d. Plnum: Nw York, rank J. Th Mathmatics of Diffusion larndn Prss: Oxford, El-Gundi M. S. olour Rmoval from Txtil Efflunts by Adsorption Tchniu Wat. Rs., 1991, 25, Fornwalt H. J. Hutchins, R. A. Purifying Liuids with Activatd arbon. hm. Eng. J, 1966, 73, Frndlich H, Th dy adsorption is losungn (Adsorption in Solution), Z Phys, hm. 1906, 57: Langmuir I, Th adsorption of gass plan surfacs of glass, mica and platinum. J. Am.Soc., 1918, 579, Langmuir I, Th adsorption of gass plan surfacs of glass, mica and platinum. J. Am.Soc., 1918, 579, Intrnational Journal of Latst Rsarch in Scinc and Tchnology. 13. Fridal, R. A. Quisr J. A. Infrard Analysis of Bitumnous oal and Othr arbonacous Matrials. Anal. hm, 1956, 28, Gadsn J. A. Infrard Spctra of Minrals and Rlatd Inorganic ompounds Buttrworths: London, Gupta G S. Prasad, G. Singh V. N. Rmoval of hrom Dy from arpt Efflunts using oal II (Rat procss). Environ. Tchnol. Ltt., 1988, 9, Namasivayam. Munisamy N. Gayathri K. Rani M and Rnganathan K. Biors Tchnol, 1995, 57, Wbr T W, hakravorti R K, Por and Solid diffusion modls for fixd bd adsorbrs. J. Am. Inst, hm. Eng, 1974, 20, McKay G, Blair H S, Gardnr J R, Adsorption of dys on chitin. I. Euilibrium Studis J. Appl, Polym, Sci. 1982, 27, hin S H, layton W R, Application of Elovich Euation to th kintics of Phosphat rlas and sorption on soil, Soil Sci. Sco, Am. J. 1980, 44, Wbr W. J. Morris J.. Kintics of adsorption on arbon from solution. J, Sanitary Eng, Div. 1964, 90, Arivoli S Vnkataraman B R, Rajachandraskar T and Hma M, Rs. J. hm Environ., 2008, 17, 70. M 0 (Mg / L) Q (Mg / L) Rmoval % 30 o 40 o 50 o 60 o 30 o 40 o 50 o 60 o 30 o 40 o 50 o 60 o EQUILIBRIUM PARAMETERS FOR THE ADSORPTION OF Rh-B ONTO APAN TABLE: 3. ISOTHERM PARAMETER FOR THE ADSORPTION OF Rh-B ONTO APAN Modl Frundlich Langmuir Tmkin Hurkins-Jura Halsay Radlich-Ptrson Dubinin-Radushkvich Jovanovic BET onstant Tmpratur ( o ) K f (mg/g) (L/mg) 1/n n Q m (mg/g) b (L/mg) b T (J/mol) K T (L/mg) A H (g 2 /L) B H (mg 2 /L) K Ha (mg/l) n Ha g K R (L/g) s (mg/g) K D 10-4 mol 2 kj K J (L/g) max (mg/g) BET (L/mg) s (mg/g) ISSN:

8 Intrnational Journal of Latst Rsarch in Scinc and Tchnology. TABLE: 4. DIMENSIONLESS SEPERATION FATOR (R L ) FOR THE ADSORPTION OF Rh-B ONTO APAN ( i ) 30 o 40 o Tmpratur 50 o 60 o TABLE: 5. THERMODYNAMI PARAMETER FOR THE ADSORPTION OF Rh-B ONTO APAN G o ( 0 ) 30 o 40 o 50 o 60 o H S E a S * % Rmoval of Rh-B % Rmoval of Rh-B o n ta c t T im in m in F ig :1 - E ff c t o f o n ta c t T im o n th R m o v a l o f R h -B [R h -B ] = 5 0 m g /L ;T m p r a tu r 3 0 o ;A d s o rb n t d o s = 5 0 m g /5 0 m l Adsorbnt dos in mg Fig;2- E ffct of A dsorbnt dos on th rm oval of R h-b [R hb ]= 50m g/l ; ontact T im 60m in;t m pratur % Rmoval of Rh-B % Rmoval of Rh-B Initial ph F ig ;3 - E ffct of In itial p H o n th rm o v al o f R h-b [R hb ]=50 m g /L ;T m pratu r 30 o ;A dsorbn t d o s= 50 m g/5 0m l on. of othr ion in m g/l Fig.4-Effct ionic strngth on th adsorption of R h-b [RhB ]=50 mg/l;ontact tim=60 min;dos=50 mg/50 ml ISSN:

9 Intrnational Journal of Latst Rsarch in Scinc and Tchnology Rh-B Dsorption % NaOH oncntration, M Fig.5- Effct of NaOH oncntration on Rhodamin-B dsorption TABLE: 6. THE KINETI PARAMETERS FOR THE ADSORPTION OF Rh-B ONTO APAN Tmp Psudo scond ordr Elovich modl Intraparticl diffusion k 2 h K id ISSN: