Adsorption of Reactive Black M-2R on Different Deacetylation Degree Chitosan

Transcription

1 Adsorption of Ractiv Black M-2R on Diffrnt Dactylation Dgr Chitosan Fang Li, Chunmi Ding Anhui Univrsity of Polytchnic, Wuhu, Anhui CHIA Corrspondnc to: Chunmi Ding mail: ABSTRACT Diffrnt dgr of dactylation (DD) chitosan was prpard and usd for th rmoval of a Ractiv black M-2R (RBM) from auous solution. Th ffcts of tmpratur (298 K~323 K), chitosan dosag, dgr of dactylation on RBM rmoval wr invstigatd. Th adsorption uilibrium was rachd within on hour. In ordr to dtrmin th adsorption capacity, th sorption data wr analyzd by using linar form of Langmuir, Frundlich and Tmpkin isothrm uation. Langmuir uation shows highr conformity than th othr two uations. From th kintic xprimnt data, it was found that th sorption procss follows th psudoscond-ordr kintic modl. Activation nrgy valu for sorption procss was found to b kj mol 1. Chitosan with 66% dactylation dgr (DD) xhibitd good adsorption prformanc for RBM. In ordr to dtrmin th intractions btwn RBM and chitosan, FTIR analysis was also conductd. Kywords: Chitosan;Ractiv Black M-2R; Adsorption; Dactylation dgr ITRODUCTIO Ractiv dys ar widly usd for txtil dying, papr printing, lathr dying, color photography and as additivs in ptrolum products. Contamination of watr rsourcs with dys is not dsirabl sinc it damags th asthtic natur of watr and rducs th light pntration dgr through th watr s surfac. Furthrmor, th colord fflunts may contain toxic, carcinognic, mutagnic or tratognic chmicals for microbs and fish spcis. Approximatly 1, diffrnt dys and pigmnts ar usd in industry. Most of thm ar difficult to biodgrad sinc thy hav complx aromatic molcular structurs and synthtic origins 1. Th rmoval of color from dy fflunts is a big problm du to th difficulty in trating such wast watrs with convntional tratmnt mthods. Th most common usd mthods of color rmoval ar physical or chmical procsss. All ths mthods hav diffrnt color rmoval capabilitis, capital costs, and oprating rats. Th liuid phas adsorption procsss hav bn shown to b highly fficint for th rmoval of dys from industrial wast watr 2-5. Activatd carbon is th most popular adsorbnt. It has bn usd with grat succss 6-7. Howvr, activatd carbon is xpnsiv and it is mor costly to rgnrat and rus. Sorption procss bcoms conomic, if th adsorbnt is inxpnsiv and dos not ruir any xpnsiv pr-tratmnt. Thus, thr is a continuous sarch for altrnat low cost adsorbnt matrial to rplac high cost activatd carbon for watr and wast watr tratmnt 8,9. Many invstigators hav studid th fasibility of using low cost substancs for th rmoval of various dys and pollutants from wastwatrs Chitosan is usually obtaind from wast matrials from th safood procssing industry, mainly shlls of crabs, shrimp, prawns, and krill 15. Shrimp shll wast is a hug wast from China safood procssing industris (mor than 1,, tons pr yar). Ths wasts ar low cost, availabl in abundanc, and suitabl for producing chitosan polymr. Chitosan (CS) has linar polymr of actylamino-d-glucos with a porous structur. Rcntly, chitosan which is usd as an adsorbnt has drawn attntions du to its high contnts of amino and hydroxyl functional groups showing high potntials of th adsorption of dys 16-. Dactylation dgr (DD) may hav an ffct on adsorption capacity of CS, howvr, thr ar limitd studis about th dactylation dgr ffct on adsorption capacity of CS toward dys. Th aim of th prsnt study was to invstigat th ffct of tmpratur (298 K~323 K), chitosan dosag, and dactylation dgr on th adsorption of ractiv black M-2R (RBM) (s thir molcular Volum 6, Issu

2 structurs in Figur 1), and to dtrmin th optimum conditions for th maximum rmoval of RBM by chitosan from auous solution. For this purpos, som known kintic uations wr usd to dal with kintic data. Also, adsorption isothrm uations wr usd to trat th uilibrium data. O 2 O FIGURE 1. Cr/2 O a 2 O 3 S H SO 3 a Volum 6, Issu 3-11 Cl H Th molcular structurs of RBM. SO 2 C 2 H 4 OSO 3 a MATERIALS AD METHODS Matrials Chitosan with 92% dgr of dactylation, chitin (Qingdao Jinhu Ocan Biology Co.,Ltd, China), ractiv black M-2R, thanol, actic acid, and sodium hydroxid usd in th xprimnt wr of analytical and purchasd from ational Mdicins Co., Ltd, China. Prparation Of CS 15 g chitin was tratd with 4 ml of 4% sodium hydroxid solution with hating and agitation (6 r/min), Th raction tmpratur was 11 C and th raction tim was carrid out at 6, 1 and 18 min, in ordr to obtain 55 ± 5%, 66 ± 3% and 88 ± 3% of dactylation, rspctivly. Batch Kintic Studis Exprimntal kintic data for RBM adsorption by chitosan wr invstigatd at tmpraturs of 298 K, 8 K, 318 K and 328 K. All th kintic xprimnts wr prformd at th natural ph of solutions..5 g of CS with 92% DD was contactd with 1 ml RBM solutions in a sald flask agitatd vigorously by a magntic stirrr using a watr bath maintaind at a constant tmpratur. Th stirring spd was kpt constant at 4 r/min. A volum of.5 ml was pipttd and all th sampls wr cntrifugd at 5 r/min for 5 min and do not sttl down asily and th rmaining concntration of dy in solution was masurd with a visibl spctrophotomtr modl 722- at a wavlngth of6 nm. Aftr th dtrmination of absorbanc, this volum was rturnd to th flask containing th suspnsion. In all cass, th working ph (about ) was that of th solution and was not controlld. Th amount of RBM adsorbd on chitosan was calculatd by th following uation: 26 C m Co V (1) whr is th amount of RBM adsorbd (mg/g), C o and C th initial and uilibrium concntration of RBM (mg/l), V th volum of th solution (ml) and m th amount of adsorbnt (g). Batch Isothrm Studis Exprimntal uilibrium data for RBM adsorption by chitosan wr invstigatd at tmpraturs of 298 K, 8 K, 318 K and 328 K..5 g of chitosan with 92% DD was mixd sparatly with 1 ml solutions containing diffrnt RBM concntrations (8~18 mg /L). Th contact tim was dtrmind by kintic xprimnts using th sam conditions. Th suspnsions wr agitatd with a constant spd of 4 r/min for 2 h. Thn, th suspnsions wr dcantd and th solutions wr analyzd for RBM concntrations using 722- spctrophotomtr. All xprimnts wr conductd in triplicat, and somtims rpatd again and th man valus hav bn rportd. RESULTS AD DISCUSSIO Adsorption Kintics Figur 2 shows th ffct of contact tim on adsorption at diffrnt tmpraturs. It can b sn from Figur 2, uilibrium was almost stablishd within 1 h. To optimiz th dsign of an adsorption systm of RBM onto chitosan, it was dmd ncssary to stablish th most appropriat corrlations for th uilibrium data for ach systm. Thrfor, svral kintic modls including th psudo first ordr uation E. (2), psudo scond ordr uation E. (3), and th intraparticl diffusion modl E. (4) wr applid to dtrmin adsorption mchanism. (mg/g) t (min) 298k 8k 318k 328k FIGURE 2. Effct of tim on th adsorption of RBM on CS at diffrnt tmpraturs.

3 1 t t k (2) 1 t 1 1 t 2 k 2 (3) (mg/g) K 318K 8K 298K.5 k pt C Whr t is th amount of RBM adsorbd (mg/g) on chitosan at various tim t (min), 1 th maximum capacity (mg/g) for th psudo first ordr adsorption, k 1 th psudo-first-ordr rat constant for th adsorption procss (min 1 ), 2 th maximum adsorption capacity (mg/g) for th psudo-scondordr adsorption, k 2 th rat constant of psudoscond-ordr for th adsorption (g mg 1 min 1 ), k p th intraparticl diffusion rat constant (mg g 1 min.5 ), C th intrcpt for th intraparticl diffusion modl (mg/g). Th rsults wr givn in Tabl I. Th Adsorption Isothrms An adsorption isothrm shows how th adsorbat molculs partition btwn th liuid and solid phass whn th adsorption procss rachs uilibrium conditions. Dy concntration plays an important rol in affcting th adsorption capacity of CS. TABLE I. Adsorption kintic paramtrs. (4) C (mg/l) FIGURE 3. Adsorption isothrms of RBM on chitosan at diffrnt tmpraturs. Figur 3 shows th ffct of initial dy concntration on adsorption capacity of RBM for CS. Clarly, adsorption capacity of CS incrasd sharply with incrasing th initial concntration of dy. Thr diffrnt adsorption isothrms wr usd in ordr to corrlat th uilibrium adsorption data. Th adsorption isothrms usd hr wr th Langmuir E. (5), Frundlich E. (6) and th Tmpkin isothrm E. (7) in libralizd form sparatly. C C 1 (5) ml m ln ln K nlnc (6) f 298K 8K 318K 328K Th psudo-first-ordr k R Th psudo-scond-ordr k R Intraparticl difffusion k p C R RT RT ln A lnc (7) b b T Whr m is th maximum adsorption capacity of th adsorbnt (mg/g), (mg/g) and C (mg/l) ar th uilibrium dystuff concntrations in th solid and liuid phass, rspctivly, L is Langmuir constant rgarding th adsorption nrgy. K f is rlativ adsorption capacity (mg/g), n is htrognity factor (adsorption intnsity). A (l/g) and b T (J/mol) ar th Tmpkin constants. Linar rgrssion was fruntly usd to dtrmin th most fittd isothrm. Th constants togthr with th R 2 valus ar shown in Tabl II. T Volum 6, Issu

4 TABLE II. Adsorption Isothrm constants for RBM onto chitosan at diffrnt tmpraturs. 298K 8K 318K 328K Langmuir constant m L R R L Frundlich constant n R K f Tmpkin constant b t A R As it is sn from Tabl II, th corrlation factors (R 2 ) indicats that bttr applicability was obtaind using linarizd Langmuir than Frundlich isothrms and Tmpkin isothrms. Th ssntial charactristics of th Langmuir isothrm can b xprssd in trms of a dimnsionlss constant, sparation factor or uilibrium paramtr, R L, which is calculatd using th following uation E. (8): R 1 L 1 LC (8) Th rang of R L valu is significant in dfining th natur of adsorption Tabl II. R L valus li btwn and 1, indicating that on-going adsorption procss is favorabl for th dy using chitosan as adsorbnt. Th Frundlich paramtrs K f valus ar rducd by incrasing tmpratur. This rsult shows that adsorption capacitis of chitosan incras whn tmpraturs dcras. Th valus of n ar smallr than 1, which also rflcting a favorabl adsorption. Effct Of Th Dactylation Dgr On Th Adsorption of RBM Figur 4 shows th ffct of amin groups in th chitosan polymr on RBM adsorption for four diffrnt dactylation dgrs (55%, 66%, 88%, 92%), in th following conditions: uilibrium ph of 6.6, tmpratur of 298 K and.25 g of chitosan, th bst adsorption capacity was obsrvd for a dactylation dgr of 66%. Whn th dactylation dgr was kpt low (55%), it was obsrvd a rduction in th binding capacity of CS. In this cas, a smallr numbr of amin groups in polymr ar gnratd, rsulting in lss adsorption. A high dactylation dgr dos not lad to an improvmnt of RB binding. Long dactylation raction tim inducs high dactylation dgr. Howvr, it also inducs polymr dgradation, rsulting in chains with low avrag molcular wight. Th polymr chains with ithr low molcular wight and/or its fragmnts ar rlasd from th coild structur of CS to th surrounding liuid, affcting th adsorption capacity of CS. Effct of CS Dosag On Adsorption Th dpndnc of th dosag of adsorbnt usd on th adsorption of dy was studid in th condition of a dactylation dgr of 66%, V=1 ml, C o =19 mg/l and tmpratur of 298 K and th rsults ar shown in Figur 5. Th amount of adsorbnts usd was varid from.1 g to.1 g whil th othr paramtrs wr kpt constant. Basd on Figur 5, whn th dosag of chitosan was blow.1 g, it is found that an incras in th adsorbnt dosag can incras th prcntag of dy rmoval from th solution. This is xpctd bcaus by incrasing th adsorbnt dosag, th numbr of adsorption sits availabl for adsorbnt -adsorbat intraction is incrasd as wll. Thr will b a dcras in th adsorption capacity whn th dosag of chitosan was abov.15 g. Th first rason is that an incras in th adsorbnt dosag at constant dy concntration and volum, will lad to unsaturation of th adsorption sits, Th scond is du to th particulat intraction such as aggrgation rsulting from high adsorbnt dosag contributs to this obsrvation. Th bst adsorption capacity of 146mg/g was obsrvd for a dosag chitosan of.1 g. Volum 6, Issu

5 (mg/g) t (min) 92% 88% 55% 66% FIGURE 4. Effct of CS dactylation dgr on adsorption of RBM. (mg/g) FIGURE CS dosag (g) Effct of CS dosang on adsorption of RBM. FTIR Analysis Th FTIR spctra of chitosan bfor (2) and aftr adsorption (1) wr shown in Figur 6. Th wid band at 34 cm 1 shown in th spctrum of chitosan is attributd to strtching vibration of hydroxyl group of chitosan. This band was shiftd to 3424 cm 1 whn RBM was adsorbd. It may indicat a hydrogn bond btwn RBM and OH groups of chitosan. Th band at 2876 cm 1 shown in CS is assignd to th C H strtching vibration of polymr backbon. Thr was significant dcras for that band in th spctrum of RBM. This band was shiftd from 2876 to 2856 cm 1. This can b considrd as an vidnt for th intraction btwn chitosan and RBM cation 11. Th band at 1417 cm 1 in th spctrum of chitosan is du to C-H bnding, which was appard as a duplicat at 1419cm 1 in th spctrum of chitosan aftr adsorption. Th bands obsrvd at 1652 and 1596 cm 1 corrspond to H bnding vibrations. Ths bands wr shiftd from to 1643 and 156 cm 1 whn th adsorption of RBM occurs. Ths changs may b owing to wak intractions btwn RBM and chitosan λ cm -1 FIGURE 6. FTIR spctra of chitosan (1) bfor and (2) aftr adsorption of RBM. SEM Analysis Th surfac morphology Figur 7 of chitosan bfor and aftr adsorption was xamind by mans of scanning lctron microscopy (SEM, S48) at an acclrating voltag of 5 kv. As it is known, SEM is on of th most widly usd surfac charactrization mthod. Chitosan has htrognous surfac and micro-pors smallr than 5 μm as sn from its SEM micrographs. Ths pors ar vry suitabl placs for th sorption of RBM. In addition to this, thr ar som RBM micro-particls obsrvd as shown from Figur 7(b), which may vrify adsorption phnomnon btwn th RBM and chitosan. (a) FIGURE 7. SEM spctra of chitosan bfor (a) and aftr adsorption (b) of RBM. 1 2 (b) COCLUSIOS Th rsults in this study show that highly abundanc and low cost biopolymr chitosan can b utilizd as an adsorbnt for th rmoval of RBM from auous solution. Th sorption data indicat that Langmuir Volum 6, Issu

6 uation provids a bttr fit than Frundlich uation and Tmpkin isothrms. Thus, it suggsts th monolayr sorption of RBM onto chitosan. Th kintic xprimnts imply that sorption procss obys th psudo-scond-ordr kintic modl. Th tmpratur strongly influncd th adsorption procss. It is clar that th 2 (maximum adsorption capacity for th psudo scond- ordr adsorption) valus ar dcrasd by incrasing th tmpratur. From th kintic study, it was found that activation nrgy valu for RBM sorption onto chitosan was gratr than kj mol 1 and CS with 66% dactylation dgr xhibitd a good binding for RBM. Th bst adsorption capacitis wr found to b 146 mg/g whn th conditions for this study wr a dactylation dgr of 66%,.1 g adsorbnt dosag, 298 K and 19 mg/l initial concntration rspctivly. ACKOWLEDGMET This work was supportd by th atural Scinc Foundation of Anhui provinc (3KJ82D and KJ9B15). REFERECES [1] E. Dmirbas.; M. Z. as.; asbatch kintic and uilibrium studis of adsorption of Ractiv Blu 21 by fly ash and spiolit; Dsalination, 9, 243:8 21. [2] KARA, S.; AYDIER, C.; DEMIRA, S. E.; Modling th ffcts of adsorbnt dos and particl siz on th adsorption of ractiv txtil dys by fly ash; Dsalination, 7, 212 : [3] Alkan, M.; Clikcapa, S.; Dmirbas, O.; Rmoval of ractiv blu 221 and acid blu 62 anionic dys from auous solutions by spiolit; Dys Pig,5, 65: [4] OZACAR, M.; SEGIL, A. I.; Adsorption of mtal complx dys from auous solutions by pin sawdust; Biors. Tchnol, 5, 96: [5] Mall, I, D., Srivastava, V. C.; Agarwal,. K, t al. Rmoval of congo rd from auous solution by fly ash and activatd carbon: Kintic study and uilibrium isothrm analyss; Chmosphr, 5, 61: [6] OzdmIR, O.; Armagan, B.; Turan, M.; Comparison of th adsorption charactristics of azoractiv dys on mzoporous minrals; Dys Pig, 4, 62: [7] Wu, C. H.; Adsorption of ractiv dy onto carbon nanotubs: Euilibrium, kintics and thrmodynamics ; Journal of Hazardous Matrials, 7, 144: [8] Ong, S. T.; L, C. K.; Zainal, Z.; Rmoval of basic and ractiv dys using thylndiamin modifid ric hull; Biors. Tchnol, 7, 98: [9] Akkaya, G.; Ozr, A.; Biosorption of Acid Rd 274 (AR 274) on Dicranlla varia: Dtrmination of uilibrium and kintic modl paramtrs; Procss Biochm, 5, 4: [1] Antonio, R.; Cstari, A.; Eunic, F.S.; Th rmoval of th indigo carmin dy from auous solutions using cross-linkd chitosan Evaluation of adsorption thrmodynamics using a full factorial dsign; Journal of Hazardous Matrials, 8,153: [11] Zhra, B. I.; Zvri, O.; Sorption of malachit grn on chitosan bad; Journal of Hazardous Matrials; 8, 154: [12] Al-Dgsa, Y. S.; Khraishhb, M. A. M. Adsorption charactristics of ractiv dys in columns of activatd carbon; Journal of Hazardous Matrials, 9, 165 : [13] iramol, S.; Wong, A.; Paitip, T.; Adsorption mchanism of synthtic ractiv dy wastwatr by chitosan; Journal of Colloid and Intrfac Scinc, 5, 286: [14] Gorg, Z. K.; ikolaos,k.; Ractiv and basic dys rmoval by sorption onto chitosan drivativs; Journal of Colloid and Intrfac Scinc, 9, 331: [15] Morais, W. A.; Frnands, A. L. P.; Sorption studis of a modl anionic dy on crosslinkd chitosan; Colloids and Surfacs A: Physicochm. Eng. Aspcts, 7, 31: 31 [16] Wong, Y. C.; Szto, Y. S.; Chung, W. H.; Adsorption of acid dys on chitosan uilibrium isothrm analyss; Procss Biochmistry, 4, 39: [17] Piccin, J.S.; Viira, M. L. G.; Gonlvs, J. O.; Adsorption of FD&C Rd o. 4 by chitosan: Isothrms analysis; Journal of Food Enginring, 9, 95:16. [18] Ilhan, U.; Kintics of th adsorption of ractiv dys by chitosan; Dys and Pigmnts, 6, 7: Volum 6, Issu 3-11

7 [19] Oualid, H.; Fthi S. Sorption of malachit grn by a novl sorbnt, dad lavs of plan tr: Euilibrium and kintic modling; Chmical Enginring Journal, 8, 143: [] Azlan, K.; Wan, S.; Wan,.; Chitosan and chmically modifid chitosan bads for acid dys sorption; Journal of Environmntal Scincs, 9, 21: AUTHORS ADDRESSES Chunmi Ding Fang Li Anhui Univrsity of Polytchnic Biijing Middl Road Wuhu, Anhui 241 CHIA Volum 6, Issu