ROLE OF SAWDUST IN THE REMOVAL OF IRON FROM AQUEOUS SOLUTION

Transcription

1 AJSTD Vol. 23 Issu 3 pp (2006) ROLE OF SAWDUST IN THE REMOVAL OF IRON FROM AQUEOUS SOLUTION H.B. Snin *, O. Subhi, R. Rosliza, N. Kancono, M.S. Azhar, S. Hasiah, and W.B. Wan Nik Faculty of Scinc and Tchnology, Collg Univrsity of Scinc and Tchnology Malaysia KUSTEM), Kuala Trngganu, Trngganu, Malaysia Rcivd 28 Sptmbr 2005 ABSTRACT Sawdust, inxpnsiv matrial has bn utilizd as an absorbnt for th rmoval of iron from auous solution for thir saf disposal. Th adsorption xprimnts of untratd sawdust (SD) and tratd sawdust (SDC) hav bn carrid out at room tmpratur using th batch tst. Th Langmuir and Frundlich isothrms wr usd to obsrv sorption phnomna of sawdust in th rmoval of iron. Th rsults indicat that th sawdust was capabl in rmoving iron in auous solution. Th rsults hav shown that th Langmuir isothrm was found wll fittd into th xprimntal data as compard to th Frundlich isothrm. It was found that, chmisorptions and physisorption wr th prim mchanism for th procss of adsorption to occur btwn th sawdust and iron. Th rsults also provd that th acid sulphuric tratd sawdust is much bttr than that of untratd sawdust as an adsorbnt for iron. 1. INTRODUCTION In rcnt yars considrabl attntion has bn dvotd to th study of rmoval of havy mtal ions from solution by adsorption using agricultural matrials such as wast wool, nut wasts, tr barks, modifid cotton and sawdust [1]. Many agricultural byproducts such as bark and sawdust ar low cost (or no conomic valu) matrials. Sawdust from timbr industry is oftn considrd as wast matrial and widly availabl. Iron imprgnatd sawdust has bn usd as an adsorbnt for phnolic compounds. Som prvious invstigations on th rmoval of havy mtal ion with sawdust hav bn rportd [2]. Th prsnt study undrtaks th adsorption capacity of mapl sawdust for th rmoval of iron from auous systms. 2. MATERIALS AND METHODS Th untratd and tratd sawdust wr usd as an absorbnt for th rmoval of iron from auous solutions. Th sawdust was sivd in rang of 850 μm to standardiz th siz of th sampl and washd svral tims with distilld watr. Untratd sawdust was drid in sunlight and tratd sawdust mixd with sulphuric asid (1 M) was drid at 110 C. Th initial concntration F of 0, 1.75, 3.5, 7.0 and 14.0 mg/l wr usd. Typically, g sawdust Corrsponding author -mail: snin@kustm.du.my

2 H.B. Snin, t al Rol of sawdust in th rmoval of iron from auous solution was addd in sparat flasks ach containing 100 ml of th tst solution of F and stirrd in a shakr at 200 rpm. Aftr raching targt contact tim, suspnsions wr filtrd and analyzd using an atomic absorption spctromtr (AAS). Th adsorption xprimnts wr carrid out at room tmpratur and fiv hours was judgd to b sufficint to rach uilibrium. 3. RESULTS AND DISCUSSION 3.1 Effct of concntrations Figur 1 illustrats th sorption of iron onto th sawdust for diffrnt initial concntrations of F. It can b sn that th adsorption of iron incrasd with incrasing of concntrations of F solution Concntration (mg/l) 16 Fig. 1: Absorbanc vs. concntration (calibration curv for F (II)) Adsorption fficincy (%) SD SDC Wight (g) 12 Fig. 2: 224 Adsorption fficincy of F (II) using SD and SDC

3 AJSTD Vol. 23 Issu Effct of adsorbnt Figur 2 shows that th adsorption fficincy iron by using SD and SDC. Th rsults had shown that th adsorption fficincy for iron by both SD and SDC incrasd with th addition of sawdust. Th maximum adsorption by SD was found to b 71.7% whrby for th SDC was 95.7%. As a consunc SDC has mor affinity for adsorption of iron as compard to that of SD. 3.3 Adsorption modls and mchanism Th simplst adsorption is basd on th assumptions that vry adsorption sit is uivalnt and that th ability of a particl to bind togthr is indpndnt of whthr or not adjacnt sits ar occupid [1]. Th Langmuir and Frudlich isothrms dscribd wll for th obsrvd sorption phnomnon of iron. Figurs 3 and 4 display S-typ shap for sorption isothrm for SD and SDC which dscribs th intraction of th adsorbat and th adsorbnt. It showd that th rlation of adsorbnt dosag incrass with th incrmnts of uilibrium concntration obtaind. Th amount of F(II) adsorb pr gram of sawdust, (mg/g) Th uilibrium concntration, C (mg/l) Fig. 3: vs. C (batch tst) by using SD 0.45 Th amount of F(II) adsorb pr gram of sawdust, (mg/g) Th uilibrium concntration, C (mg/l) Fig. 4: vs. C (batch tst) by using SDC 225

4 H.B. Snin, t al Rol of sawdust in th rmoval of iron from auous solution To analyz th fitnss of adsorption isothrm to th xprimntal, th data for th uptak of mtal ions by sawdust has bn dtrmind in accordanc with a linar form of Langmuir isothrm uation [3]: = + ab. C a (1) Th slop of th graph rprsntd by 1/ab whil 1/a is shows th intrcption of th graph on th Y-axis. Th constant a rfrs to th adsorption capacity and constant b is an indicator for molcular siz of absorbat. Th linar lin of Langmuir uation fittd wll into th xprimntal data as shown in Figs. 5 and / /C Fig. 5: Linar Langmuir isothrm of F (II) sorption on SD / /C Fig. 6: Linar Langmuir isothrm of F (II) sorption on SDC 226

5 AJSTD Vol. 23 Issu 3 Th linar Frundlich uation can b xprssd by [3] Log 1 ( logc ) = + log K f (2) whr th slop of th graph rprsntd by 1/n and log K f is shows th intrcption of th graph on th Y-axis. Th valu of K f indicats th adsorption capacity and th constant n rfrs to th mpirical constant rlatd to th strngth bonding btwn F and th sawdust. Th linar lin of Frundlich uation fittd linarly into th xprimntal data as shown in Figs. 7 and 8. n Log C Log Fig. 7: Linar Frundlich isothrm of F (II) sorption on SD Log C Log Fig. 8: Linar Frundlich isothrm of F (II) sorption on SDC All th rlatd paramtrs of th linar Langmuir and Frudlich uations for F on sawdust in auous solutions ar summarizd in Tabls 1 and 2. A comparison is also bing mad btwn th thr isothrms plottd in Figs. 9 and 10. As shown by Tabl 1, th Langmuir and th Frudlich isothrms wr satisfactory fittd to th xprimnt data as indicatd by thir corrlation cofficints. Th Langmuir isothrm shows a bttr fit of adsorption data as compard to that of th Frudlich isothrm. It can b concludd that th chmical absorption or 227

6 H.B. Snin, t al Rol of sawdust in th rmoval of iron from auous solution chmisorption and physical absorption or physisorption procsss wr th main mchanisms of adsorption that occurrd btwn th sawdust and iron. It is du to th formation of a chmical bond btwn th absorbing molculs and th surfac of th sawdust. Th rsults also show that th chmisorptions procss is mor dominant as compard to physisorption (mg/g) Exprimnt Frundlich Langmuir C (mg/l) Fig. 9: Fitting of Langmuir and Frundlich isothrm into th xprimnt data for SD Tabl 1: Langmuir adsorption uation for SD and SDC Langmuir isothrms Untratd sawdust (SD) Tratd sawdust (SDC) Langmuir uation C = C C = C Constant a (mg/g) Constant b (L/mg) R Tabl 2: Frundlich adsorption uations for both SD and SDC Frundlich isothrms Untratd sawdust (SD) Tratd sawdust (SDC) Frundlich uation =.0138C 0 = C Adsorption capacity, k f n, constant R

7 AJSTD Vol. 23 Issu (mg/g) (mg/g) Exprimnt Langmuir Frundlich C C (mg/l) Fig. 10: Fitting of Langmuir and Frundlich isothrm into th xprimnt data for SDC 4. CONCLUSIONS Th rsults of th invstigation hav shown that sawdust was found to b a promising absorbnt for th rmoval of iron from auous solutions. Th tratd sawdust has mor capability in rmoving iron as compard to that of untratd or th natural sawdust. Adsorption of th iron is dpndnt on th initial concntrations of absorbnt and th sorbat. Th Langmuir isothrm was found wll fittd into th xprimntal data as compard to that of th Frudlich isothrm in thir adsorption procsss. Basd on this finding, th chmisorption and physisorption wr th main mchanisms of adsorption that occurrd btwn iron and th sawdust. Adsorption mchanisms studis rvald that th chmisorptions procss givs a significant contribution as compard to that of physisorption. ACKNOWLEDGEMENT W gratfully thank Mr. Asmadi Ali of Dpartmnt of Enginring Scinc, KUSTEM for his valuabl suggstion about mthod for th rmoval of iron in auos solution. W would lik to acknowldg th financial support from KUSTEM. REFERENCES 1. Shukla, S.S., Yu, L.J., Dorris, K.L., and Shukla, A. (2005), Rmoval of nickl from auous solutions by sawdust, J. Haz. Mat., vol. 121, pp Yu, B., Zhang, Y., Shukla, A., Shukla, S.S., and Dorris, K.L. (2001), Th rmoval of lad from auous solutions by sawdust adsorption, J. Haz. Mat., vol. 84, pp Őzacar M. and Sngil, I.A. (2005), Adsorption of mtal complx dys from auous solution by pin sawdust, Biorsour Tchnol., vol. 96, no. 7, pp Ajmal, M., Khan, A.H., Ahmad, S., and Ahmad, A. (1998), Rol of sawdust in th rmoval of coppr (II) from industrial wasts, Wat. Rs., vol. 32, no. 10, pp Shukla, A., Zhang, Y.H., Duby, P., Margrav, J.L., and Shukla, S.S. (2003), Th rol of sawdust in th rmoval of unwantd matrials from watr, J. Haz. Mat., vol. 95, pp