KH NNG DEHYDRAT HA V DECACBOXYL HA CA ACID CITRIC

NGHIN CU NG DNG MN CA V BNG VI PH THI T CY TRM BNG VNG TRONG X L MT S KIM LOI NNG TRONG NC THIAPPLIED RESEARCH on heavy metal removal in treatment wastewater by using sawdust AND WASTE SILK-COTTON of Acacia auriculiformis A. Cunn. ex BenthPhm Thnh Qun, Nguyn Thng ng, Tng Thanh DanhTrng i Hc Bch Khoa HQG HCM

Abstract: The lignocellulose material is activated by citric acid, which can adsorb heavy metals in wastewater as effectively as Zeolit. In this article, sawdust and waste silk-cotton of Acacia Auriculiformis A.Cunn.Ex Benth from Long An are selected to study. Materials are activated by acid citric by soaking 24h in the acid, then dried and activated in 3h at 120oC, all residual acid was removed by water. Adsoprtion and ion exchange process of the materials were studied with the simulated solution contained Fe3+ and Ni2+ in different conditions. Results showed that materials activated by citric acid are able to adsorb Fe3+ of the simulated solutions are very good, above 90%. In addition, lignocelluloses of Acacia Auriculiformis A.Cunn. Ex Benth and waste silk-cotton also showed the selective effect of some other cation when tested on ion Fe, Cu, Ni in wastewater.1. GII THIUHin nay nhm ngnh cng ngh thng tin, in in t ang pht trin rt mnh trn phm vi ton cu, chng ta khng th ph nhn loi ngi v ang hng li rt nhiu t n nhng vic sn xut, ti ch cc linh kin in t trn cc bo mch trong cc thit b hin i sinh ra mt lng ng k nc thi rt c hi, cha hm lng rt cao cc ion kim loi nng. Chi ph x l nc thi cho nhm ngnh ngh ny rt tn km, do vy vic nghin cu bin tnh cc ph phm nng nghip r tin x l cc ion kim loi nng l vic lm thit thc v c nhiu ngha i vi mt nc nng nghip, ang pht trin nh nc ta [1,2,3,4]. Thi gian gn y acid citric c s dng lm tc nhn ester ha Cellulose (xem hnh 1). J.Sweeny (2006) dng acid citric hot ha g Aspen [5], Wayne E.Marshall (2006) dng acid citric hot ha v u nnh u nhn thy mt s gia tng ng k kh nng tch loi cc ion kim loi tan trong nc [6,7]. So vi cc bin php bin tnh cellulose trc , phng php s dng acid citric c nhiu u im nh iu kin phn ng n gin, tc nhn acid khng c hi, gi thnh khng cao. Phng php ny c nhiu tc gi khc ng dng rt hiu qu cho cc ph phm nng nghip nh x da, bng vi, tru [8,9]... l cc loi vt liu xp d dng cho acid citric ngm vo bn trong. Cn i vi mt s g cng, bin php ny c hiu qu khng cao [10].

Hnh 1. Ester ha cellulose bng acid citric2. NGUYN LIU V PHNG PHP2.1 Nguyn liu v ha cht Ha cht dng trong th nghim l Ni(NO3)2.6H2O, FeCl3.6H2O, nha cationit ca Anh, acid citric ca Shanou Xilong( Trung Quc) v nc ct mt ln. Cc ha cht c pha trong nc ct to cc dung dch c nng xc nh v khng qua x l g thm. Bng vi ph phm, mn ca t cy trm bng vng c s dng trong nghin cu ny.2.2 Qui trnh bin tnh vt liu lignocellulose

Bng vi ph phm, mn ca sau khi loi tp cht c hc c ngm vi dung dch acid citric 250g/l trong thi gian 01 ngy acid citric thm u v su vo bn trong cc x si. Sau lc ly vt liu em phi kh n m nh hn 20% ri hot ha 120oC-130oC trong 2-6 gi. Vt liu sau khi hot ha c ra sch acid d bng nc ct, sau phi kh t nhin ri bo qun trong cc bao plastic.2.3 Thit b nghin cuQu trnh bin tnh vt liu lignocellulose s dng t sy ca phng th nghim B mn Ha v c Khoa K thut Ha hc, i hc Bch khoa TP. HCM. Cc dung dch m phng v nc thi c cho qua ct c chiu cao H= 220mm, ng knh D = 45mm. Mu dung dch sau khi i qua ct m hnh em phn tch trn my ph hp thu nguyn t (AAS) SHIMADZU AA 6300 ti phng Ha phn tch i hc Khoa hc t nhin TP.HCM xc nh nng ion Fe, Cu, Ni. Ring i vi dung dch m phng Fe3+ c o trn my quang ph hp thu Vis ca phng th nghim B mn Ha hu c Khoa K thut Ha hc, i hc Bch khoa TP. HCM.3. KT QU V THO LUN:3.1 Kho st thi gian v nhit phn ng i vi bng vi

Tin hnh x l mu theo nh quy trnh trong mc 2.2, kho st thi gian phn ng ln lt l 2h, 3h, 4h, 5h, 6h ti cc nhit l 120 oC, 130oC. Sau khi ra xong, lc ly sn phm em i phi kh n m ph hp ri tin hnh chun ngc xc nh cc thng s ti u, t chn ra iu kin phn ng ti u. Kt qu thu c nh trong bng 1. Kt qu kho st cho thy khi tng nhit th lng NaOH tiu tn cho 1g bng vi gim,iu ny l do nhit cao, phn ng ester ha tip hai nhm COOH cn li ca acid citric nn lm gim s lng cc nhm acid t do. Bng 1: th tch dung dch NaOH 0,2 N dng chun 1g bng vi bit tnh

Thi gian (h)23456

V (ml)/g 120 oC9,059,66(*)8,857,96

V (ml)/g 130 oC8,92(*)9,518,707,63

(*)-Gi tr khng ph hp nn b loiLng NaOH tiu tn cho 1g bng vi t cc i ti nhit 120 oC trong 3 gi. Do , nhit 120oC c chn kho st i vi mn ca. Ngoi ra, bng vi cng c kho st bin tnh bng cch gia nhit bnh cu cha bng vi v dung dch acid citric bo ha ti nhit si, tuy nhin kt qu cho thy hiu qu khng tt nh cch bng vi c bin tnh bng cch tm acid citric ri sy. 3.2 Kho st thi gian v nhit phn ng i vi mn ca:Cng ging nh bng vi , i vi mn ca th lng NaOH 0,2N tiu tn cho 1g mn ca l ln nht t 5,66 ml khi kho st nhit 120oC trong 3 gi.Bng 2: th tch dung dch NaOH 0,2 N dng chun 1g mn ca bit tnh

Thi gian (h)23456

V (ml)/g

120 oC5,005,665,395,134,76

Kt qu cho thy lng NaOH 0,2N tiu tn cho 1 g bng vi bin tnh l 9,66 ml gn gp i so vi 1 g mn ca cng iu kin bin tnh (5,66 ml). Nh vy c th thy acid citric bin tnh bng vi hiu qu hn mn ca. Ngoi ra, mn ca loi lignin trc khi bin tnh cng c kho st tuy nhin, kt qu thu c cho thy khng hiu qu hn so vi mn ca cha loi lignin.3.3 Kho st dung lng v hiu sut x l:

Sau khi bin tnh bng vi v mn ca, kh nng hp ph v trao i ion ca vt liu i vi ion Fe3+ c kho st nh sau:

- Cho vo 5 cc, mi cc 250 ml dung dch cha ion Fe3+ vi nng 200 ppm

- Cho tip vo mi cc khi lng vt liu ln lt l 1g, 2g, 3g, 4g, 5g .

- Tin hnh khuy trn u, sau cho qu trnh t n cn bng trong 6 gi. Lc ly dung dch ri em i hp thu xc nh nng ion Fe3+ trong dung dch sau khi hp ph v trao i ion. Da vo nng ion Fe3+ sau lc s nh gi c dung lng v hiu sut x l ion Fe3+ ca vt liu.Kt qu kho st cho thy bng vi bin tnh c kh nng x l ion Fe3+ rt tt, t hiu sut 70-90% (bng 3).Bng 3 : Dung lng v hiu sut x l ion Fe3+ ca bng vi bin tnh

Khi lng (g)1,17702,27663,27824,45655,5275

m (%)10,75

C ban u (ppm)200

C cui (ppm)54,826,923,723,217,9

Dung lng mg/g34,621,315,111,19,2

Hiu sut (%)7286888891

Kho st trn cho thy khi tng khi lng bng vi t 1,1770 n 5,5275g th hiu sut x l tng ln t 72 n 91%. t c hiu sut x l cao th dung lng lm vic ca bng vi bin tnh gim.3.4 Hiu sut x l tng ion Fe3+ v Ni2+ trong dung dch m phngDung dch cha ion Fe3+ vi nng 200 ppm v dung dch cha ion Ni2+ vi nng 200 ppm c s dng lm dung dch m phng nh gi hiu sut x l ion Fe3+, Ni2+ ca vt liu lignocellulose bin tnh. Kt qu v hiu sut x l ion Fe3+ ca bng vi, mn ca bin tnh v nha cationit c lit k trong cc bng 4.Bng 4. Hiu sut x l ion Fe ca bng vi, mn ca v nha cationitCation cn x l Fe3+Ni2+

Khi lng vt liu (g)12

Tc lc (ml/p) 5

Th tch lc (ml)300

Nng trc lc (ppm)200

Bng viCppm, sau lc4,071,5

Hiu sut (%)98,064,3

Mn caCppm, sau lc39,97,.2

Hiu sut (%)80,161,4

Nha CationitCppm, sau lc7,470,2

Hiu sut (%)96,399,9

Kt qu cho thy, khi lng vt liu l 12g, tc lc 5 ml/p, th tch lc 300 ml, nng trc lc l 200ppm th bng vi bin tnh cho hiu sut x l ion Fe3+ tt nht 98,0%, k n l nha cationit 96,3% v thp nht l mn ca 80,1%. Cn i vi ion Ni2+, nha cationit cho hiu sut x l tt nht 99,9%, k n l bng vi 64,3% v thp nht l mn ca 61,4%.Da vo kt qu phn tch th mn ca, bng vi bin tnh x l ion Fe3+ rt tt nhng i vi ion Ni2+ th hiu sut khng tt lm..3.5 Hiu sut x l cc ion Fe, Ni v Cu trong nc thi ngnh ra bo mch in tKt qu phn tch hm lng cc kim loi nng v hiu sut x l cho tng kim loi nng ca cc vt liu khc nhau c lit k trong bng 5.Bng 5. Hiu sut x l cc ion Fe , Ni v Cu trong nc thiCation cn x lFe3+Ni2+Cu2+

Khi lng vt liu(g)20

Tc lc(ml/p) 5

Th tch lc(ml)250

Nng trc lc(ppm)2932523056

Bng viCppm, sau lc215135.31273

Hiu sut(%)26,6432,1258,34

Mn caCppm, sau lc253029,11528

Hiu sut(%)13,7144,0450,0

Nha CationitCppm, sau lc19,60,621,6

Hiu sut(%)99,5298,8599,29

Kt qu cho thy hiu sut x l ca mn ca, bng vi bin tnh tng theo th t t Fe3+, Ni2+ n Cu2+. i vi bng vi bin tnh th cc gi tr ln lt l 26,64%, 32,12% v 58,34%; cn mn ca bin tnh th cc gi tr ny ln lt l 13,71%, 44,04% v 50,0%. Cc hiu sut x l c gi tr khng cao l do nng ca cc ion kim loi nng cn tng i ln so vi khi lng vt liu s dng l 20g; v dung lng lm vic ca mn ca, bng vi bin tnh ch khong 40 mg/g. Khi x l tng ion kim loi th hiu sut x l ion Fe3+ ca mn ca, bng vi bin tnh tt hn so vi ion Ni2+. Nhng khi x l nc thi th hiu sut x l ion Ni2+ tt hn ion Fe3+, iu ny c th l do nng ca ion Ni2+ l 52 ppm b hn nhiu so vi nng ion Fe l 2932 ppm v trong mu nc thi kho st ion Fe tn ti hai dng ion Fe2+ v ion Fe3+. Hiu sut x l ca nha cationit rt cao khong 99% cho c ba ion kim loi nng kho st; v dung lng lm vic ca nha cationit cao hn nhiu so vi mn ca, bng vi bin tnh. kim tra xem nu nc thi c nng cc ion kim loi nng thp hn th hiu sut x l cho tng ion c cao hn khng; ta tin hnh pha long nc thi ban u 4 ln, ri tin hnh th nghim tng t nh trn. Kt qu hiu sut x l cc ion Fe v Cu trong nc thi c lit k trong bng 6.Bng 6. Hiu sut x l cc ion Fe v Cu trong nc thiCation cn x lFeCu

Khi lng vt liu(g), 20

Tc lc(ml/p) 5

Th tch lc(ml)250

H s pha long4

Nng trc lc(ppm)733764

Bng viCppm, sau lc82,7179,3

Hiu sut(%)88,7276,53

Mn caCppm, sau lc352,4308,0

Hiu sut(%)51,9259,69

Sau khi pha long (nng ca ion Fe v ion Cu cn li ln lt l 733 ppm v 764 ppm), nghin cu cho thy bng vi v mn ca bin tnh u c kh nng x l cc ion kim loi kh tt. Hiu sut x l ca bng vi bin tnh i vi ion Fe tng t 26,64% ln 88,72%, ion Cu tng t 58,34% ln 76,53%. Cn hiu sut x l ca mn ca bin tnh i vi ion Fe tng t 13,71% ln 51,92%, ion Cu tng t 50,0% ln 59,69%.

Kt qu thu c cho thy bng vi bin tnh c kh nng x l cc ion Fe, Cu tt hn so vi mn ca bin tnh. 4. KT LUN :Kt qu chy dung dch m phng v nc thi cho thy, bng vi bin tnh c kh nng hp v trao i ion tt hn mn ca bin tnh. iu ny l do cu trc ca bng vi xp v t lignin hn nn acid citric d dng thm u v su hn, dn n acid citric bin tnh bng vi hiu qu hn mn ca. Dung lng lm vic ca mn ca, bng vi bin tnh ch khong 40mg/g nn nu nc thi c hm lng kim loi nng cao th ta phi s dng mt khi lng vt liu nhiu hn so vi nha cationit nu mun t c hiu sut cao.Bng vi bin tnh c hiu sut x l kh tt i vi cc ion Fe, Cu (88.72% i vi ion Fe v 76.53% i vi ion Cu). Kt qu ny cho thy bng vi bin tnh hon ton c th thay th nha cationit x l nc thi c hi.TI LIU THAM KHO[1] N. A. Adesola Babarinde1, J. Oyebamiji.Babalola and R. Adebowale Sanni, Biosorption of lead ions from aqueous solution by maize leaf , Ibadan, Nigeria (2006).

[2] James S. Han, Stormwater filtration of toxic heavy metal ions using lignocellulosic materials selection process, fiberization, chemical modification, and mat formation, U.S. Department of Agriculture, Forest Service. U.S.A (1999).

[3] J.C Igwe , E.C.Nwokennaya and A.A. Abia, The role of pH in heavy metal detoxification by biosorption from aqueous solutions containing chelating agents, P.M.B 2000 Uturu, Abia State Nigeria (2005).

[4] Jame W.Patterson, Industrial Wastewater Treatment Technology, second edition, Butterworth Heinemann, Boston London Singapore Sedney Toronto Wellington (1985).

[5]. James D. Mc Sweeny, Roger M. Rowell, Soo-Hong Min, Effect of Citric Acid Modification of Aspen Wood on Sorption of Copper Ion, Journal of Natural Fibers, Vol. 3(1) (2006).

[6]. Wayne E. Marshall, Dual-functional ion exchange resins from agricultural by-products , US United States Patent 7098327 (2007)[7] Wayne E. Marshall et al, Enhanced Metal Adsorption by Soybean Hulls Modified with Citric Acid, Bioresource Technology, vol. 69, pp. 263-268 (1999).

[8] Nasim Ahmad Khan, Shaliza Ibrahim and Piarapakaran, Elimination of Heavy Metals from Wastewater Using Agricultural Wastes as Adsorbent, Malaysian Journal of Science 23: 43 51 (2004).

[9] L Thanh Hng, Phm Thnh Qun, L Minh Tm, Nguyn Xun Thm, Nghin cu kh nng hp ph v trao i ion ca x da v v tru bin tnh, Hi ngh khoa hc cng ngh ln th 10 (2007).

[10] Phm Thnh Qun, Tng Thanh Danh, Nguyn Vit c, Nghin cu kh nng x l kim loi nng ca mn ca cy trm bng vng bng phng php hp ph v trao i ion, Tp ch Ha hc, Tr. 714-718 (2009). Lin h tc gi:

Tng Thanh Danh, Khoa Ha, Trng HBK TPHCM

268 L Thng Kit, Q.10, TPHCM

Email. tongdanh@hcmut.edu.vnDi ng: 0933-833-681

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