TAP CHI HOA HQC T. 49(4) 441 -445 T H A N G 8 NAM 2011
NGHIEN CLFU SLf HAP PHU CHi (Pb^*) TREN CHITIN BI^N TJNH GHEP ACRYLONITRIN
B A N GPHU'aNG
P H A P C H I ^ UXA GAMMA Co-60
Tru-ong Thi Hanh', Nguyen Quoc Hien', Hk Thuc Huy^
'Trung tdm Nghien cuu vd Trien khai Cong ngh^ Buc xg, VAEC
^Tru&ng Dgi hgc Khoa hgc Ty nhien, DHQG TPHCM Den Toa soan 01-03-2011
Abstract
Partially deacetylated chitin was grafted with acrylonitril (Chi-g-PAN) by pre-irradiation method on Co-60 gamma source, and then was amidoximated by a reaction between hydroxylamine and cyano group. All studied samples were characterized using a number of analytical techniques, including scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The effect of pH and initial concentration of lead ions on the adsorbed capacity by amidoximated Chi-g-PAN (Chi-g-PAN/A) were also investigated. The adsorption kinetics was fit for Langmuir model, with correlation coefficient R^= 0.988. Adsorption capacity of Chi-g-PAN/A for lead ions was determined to be 0.286 mmol/g. The removal of lead ions fi-om the waste water of Dong Nai battery factory was also performed.
1. MCS DAU nhom chuc hip phu -NH2, -OH trong do cac nguyfn tir O va N con cap difn tu ty do co kha nang tao Sy 6 nhifm chi ra gay do su dung gia tang kim phiic ehelat vdi cac ion kim logi [3]. Sy khac nhau logi nay tir cupc each mgng cdng nghifp. Dgc tfnh df giua chitin va chitosan co dp deaxetyl khac nhau la dat mong, keo sgi da giiip ehi dxxoc lya chgn chf tgo kha nang hoa tan trong moi trudng axit. Bif n tfnh nhieu san pham cong nghifp, dgc bift trong san xuat chitin/chitosan nham hai muc dfch vira cai tifn dgc vu khf, xay dyng, diic tifn, chf tao pin.... Sy co mat tfnh hap phy vtra thay doi do hda tan trong moi cua ehi trong son da giiip cho son bfn mau, chdng trudng [4]. Sur dung ky thuat ghep biirc xg df hifn lai sy pha vd ciia hgp chat trong son va bong ldp. tfnh, nham dua thfm nhirng nhom chirc hap phy mdi Hang ngan tan son chi da dugc su dung d My, trudc dfn vat lifu goc, tang mat dg viing hap phu, thay ddi khi no bi cam vao nam 1978 [I]. Mdt lugng Idn chi pH dong thdi tang do chgn lgc hap phu [5].
ciing dugc tgo ra do ddt chay cac logi xang, diu. Trong cong trinh nay, chiing toi khao sat cac dgc Theo gidi khoa hgc, ham lupng chi trong mau cao trung vf cau tnic cua vat lifu chitin hifn tfnh ghep qua miic (250 micro gram/lit) cd the gay ton thuong aerylonitrin bing ky thugt biic xa va chuyfn boa nao bd, hf tifu hda, co quan sinh san, gay dau dg nhdm cyan (-CN) thanh nhom amidoxim day, thifu mau, eo giat va dgc bift nguy hiem doi (-C(NH2)=N-0H) tir cdng trinh trudc [6]. Danh gia vdi tre nhd, lam cham qua trinh phat trifn trf tuf. kha nang hip phy va trao doi ion vdi Pb^^ tir dung Mdi day, hang, tram tre em d tinh Quang Chau va djch Pb(N03)2. Dong thdi thu nghifm hip phu ion Giang To - Trung Qudc da hi nhifm chi do sinh song Pb^* cua vgt lifu tir nudc thai nha may Ic qui chi gin nha may san xuit pin [2]. Chi hifn huu trong Dong Nai cung dugc thyc hif n.
khong khf, dit va dang lo nggi nhat la tir cac nguon
nudc, thanh phin thiet yf u cho sy sdng cua sinh vat. 2. THI/C NGHIpM Hifn tgi, ciing da cd mgt sd phuong phap nhu sinh
hgc, trao doi ion, lgc, keo ty, difn phan... de xii ly 2.1. Xac dinh cac d^c trirng cua vat lifu chitin nudc thai cd kim logi ndi chung, dgc bift la chi. Tuy bien tinh
nhien, hip phu dugc danh gia la phuong phap cd
hifu qua de xu ly thai Idng, ngay ca khi nong dg kim Sy thay ddi hinh thai be mat cua vat lifu chitin logi rat thap. Mdt polyme sinh hgc dugc su dyng df bien tinh dugc thf hifn qua anh chyp SEM (Model tach kim logi tir nudc va nudc thai la chitin/chitosan. JSM-6480 LV, JEOL). Cac ket qua phan tfch nhift Sy CO mat mdt so lugng Idn nhdm ua nudc -OH cua DSC (Differential Scanning Calorimetry) va TGA don vi glueozit trong cau triic chitin/chitosan, cac (Thermogravimetric Analysis) dugc xac dinh tren
TCHH, T.49(4), 2011 may DTG-60, Shimadzu.
2.2. Hap phu Pb^* cua chitin bien tinh
Dgng hgc hip phy ciia vgt lifu chitin ghep da chuyfn hoa (Chi-g-PAN/A) duge khao sat theo phuang phap tmh. Khoang 3 g Chi-g-PAN/A dgng vay, kich thudc ~5 mm dugc lie vdi 200 ml dung djch Pb(N03)2, toe dp 80 vong/phiit, d cac nong dp Pb-' khac nhau tir 100 250 mg/l, trong khoang thdi gian 24 gid. Anh hudng cua pll den kha nang hap phy cung duge khao sat theo cac gia trj pll 1, 3, 5, 7 va 9 vdi cimg nong dg PbCNOO: 100 mg/l. Hip phy Pb'' tir nudc thai nha may ac qui chi Dong Nai ciing dugc danh gia. Ham lugng Pb'* dugc xac djnh bang pho phat xa nguy(:ii tir (ICP-AES Model Optimal 5300DV. USA)^
Dung lugng hap phy chi dugc xac djnh theo phuong trinh dang nhiet Langmuir [7]:
Nguyen Qudc Hien vd cgng su
Cc/Ye=l/Qb + Ce/Q (1) Vdi Cc: Nong dg ciia ion kim Igai trong dung djch
sau hip phy (mg/l), Ye: Nong dg cua ion kim logi da dugc hip phy (rng/g), Q: Dung lugng hip phy bao h6a (mg/g), b: Hing so Langmuir (1/mg).
3. KET QUA v A T H A O LUAN
3.1. Cac dSc trung cua vat lifu chitin bien tinh Chitin bien tinh ghep vdi aerylonitrin (Chi-g- PAN) trong cong trinh nay cd miire do ghep ~114%, vdi nong dg amidoxim thay the nhom cyan trfn Chi- g-PAN la 2,13 mmol/g [6]. Hinh 1 bieu thj qui trinh che tgo chitin amidoxim (Chi-g-PAN/A) tir chitin ghep aerylonitrin, bing cac gdc peoxit hogt hoa nho ky thugt chieu xg trudc trfn nguon gamma Co-60 trong dieu kifn cd oxi.
5 V > - 0 0 - < ^ _ H / - 0 ' < : H 3 ^ < : H - C M V o - C H ^ C H - c r
Cliitin Cliitinpeoxil
r>
> Chi-J-PAN M H , O H^ ^ Chi-g-PAN/A
LTinh 1: So do qui trinh chf tgo Chi-g-PAN/A
Anh SEM mo ta trgng thai bf mat cua cac mau chitin duge the hifn trong hinh 2, mau chitin dgng vay (a) eo be mat tron phang, tuy nhifn sau khi ghep AN bf mat mau da co sy thay doi dang ke vdi nhiing dudng nep go ghf (b). Neu xu ly bang NH2OH trfn sudn chitin se gan thfm nhirng nhom churc "ua
nudc" -OH, -NH2, cd sy "truong" rd rft cua mau, trong bf mgt chitin da chuyen hda nhu day hon (c).
Sy hap phu tgo phirc giira ion Pb'"^ va nhii-ng nhom chirc -OH, -NHj (Chi-g-PAN/A-Pb) da tgo lien ket trong mgng phan tOr lam cho hinh thai bf mat trong bang phang va ddng nhat hen (d).
. t • =4«...v i . , ^ ' , • ^%,v >.»* ,»A,? . \ '
LTinh 2: Anh SEM cua chitin (a); Chi-g-PAN (b); Chi-g-PAN/A (c); Chi-g-PAN/A-Pb (d)
TCHH, T.49(4), 2011
TGA
Nghien cuu sy hdp phu chi.
100.00-
50.0C • 92o8°C
0.00-
TGA
%
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o.oc-
0.00 100.00 200.00 300.00 400.00 500.00 600.00 000 100.00 200.00 300.00 400.00 500 00 600.00 Temp (C) Tomp i q
TGA TGA
%
lOO.OC-
o.oc-
SO.Oq- 86JS"C
%
100.0C-
0.00-
— 362.05'C
0.00 100.00 200.00 300.00 400.00 600.00 60000 100.00 200.00 300.00 400.00 500.00 600.00 Tomp IC]
Temp [C]
Hinh 3: G\kn do DSC, TGA cua (a) Chitin 25 kGy, (b) Chi-g-PAN, (c) Chi-g-PAN/A, va (d) Chi-g-PAN/A-Pb
Ket qua phan tich nhift cua cac mau chitin chifu xg tgi lieu 25 kGy (3a), chitin bien tinh ghep vdi AN (3b), roi chuyfn boa amidoxim (3c) va hap phu Pb^^
(3d) dugc trinh bay trong hinh 3. Dudng phan tfch nhift trgng lugng TGA cua mau chitin co ba giai dogn suy giam khdi lupng. Dau tien, d nhift dp dudi
100°C la do sy mat nudc, trong viing nhift dp 253°C den 328°C, sy mat 26% trpng lugng la do sy phan hiiy cau triic saeearit bao gom sy dehydrat boa vong saeaerit, depolyme hda, sy phan hiiy cac nhom acetyl, amin trong don vj cau triie cua chitin [8].
Cuoi cimg sy giam trgng lugng d vimg nhift do 334 406°C la sy pha hiiy cua chitin con lgi. Dudng DSC Clia chitin co ba dinh tda nhift (exo) tuong iing vdi nhift do 93°C chuyen hda thiiy tinh, sy pha buy cau true tinh thf ciia chitin thf hifn d dinh 352°C, mpt dinh vdi cudng dp rat thap d nhift dp 415°C do sy phan huy tiep phan tinh the ciia chitin. Sau khi thyc hifn phan iing ghep, dudng DSC cd thfm mpt dinh rpng d 535°C do anh hudng cua viing ghep den cau triic tinh thf eua chitin. Sau khi chuyen hoa nhom amin thanh amidoxim sy xuat hien hai nhom
"ua nudc" -NH2 va -OH trong amidoxim da lam cho nhift dp phan buy ciia chitin bien tfnh thap hon chitin ghep va co cudng dp dinh rat mgnh d 503''C.
Trong gian dh 4d, sy hap phy Pb^"" anh hudng nhieu den clu triic tinh thf, sy che dinh d viing tinh the thii hai CO le do sy pha vd cac lifn ket phoi tri trong viing 'bif n gidi" giira vimg vo djnh hinh va tinh the.
3.2. Khao sat kha nang hap phu Pb^* cua chitin bien tfnh
kim logi Pb^* dugc khao sat vdi cac gia trj pH = 1, 3, 5, 7 va 9, khi cho ciing mgt lugng Chi-g-PAN/A khoang 3 gam vao 200 ml dung dich muoi chi Pb(N03)2 ciing ndng do 100 mg/l. Ket qua trong hinh 4a cho thay dung lupng Pb "^ hap phy da tang dan theo pH, tgi cac difm pH = 7 va 9 lugng Pb^"^ da duge hap phy hoan toan. Nhiing nhdm -OH va -NH2 trong chitin (40% do deaxetyl) co vai tro ehinh trong phan ling lifn kft vdi kim logi. O pH thap, nhom -NH2 trong chitin hi proton hoa, ion kim logi phai canh tranh lifn kft vdi proton, trong qua trinh hap phy [7]:
Pb'" + R N H 2 ^ Pb(RNH2)' IT + RNH, -> RNH,"
(2) (3) Vi vgy, dung lupng hap phy chi cua Chi-g- PAN/A d mdi trudng axit thap hon bazo. Kft qua nay phil hgp vdi so lifu Y. H. Gad da cong bo khi cho hydrogel poly(2-acrylamido-2-metylpropran- sulfonic axit)/chitosan hap phu Cd'" va Cr^" [9].
Sy hip phy ciing mgt ion kim logi khong chi phy thugc vao pH ma cdn phy thudc vao dae trung hoa ly cua vat lifu. Dung lupng hap phy va trao doi ion tuong ling vdi so nhdm -OH va -NH2 hifn difn trfn chitin. Sau khi hifn tinh ghep roi chuyfn hoa, kha nang tach ion kim logi tir dung djch cua mau cao ban so vdi chitin chua hifn tfnh. Bang 1 so sanh kha nang hap phu Pb'" cua chitin va Chi-g-PAN/A trong nudc thai nha may ac qui chi Dong Nai, tgi ba vj tri khac nhau be dau ngudn (NMG), be da qua Ipc co (NMD) va be da xu ly (NMX). Ket qua cho thiy cac miu chitin bien tinh tach Pb'" tdt hon miu chua hifn tinh.
Anh hudng cua pH dfn qua trinh hip phu ion ^""8 ^am lugng Pb la 65,2 mg/l trong bf thai da 2+
TCHH, T.49(4), 2011 Nguyen Quoc Hien vd cgngsyc qua lgc co, Chi-g-PAN/A da hip phy Pb'"sgch, trong khi mau chitin ham lugng chi cdn lgi la 23,3 mg/l.
Bdng I: Hip phy Pb'" tir nudc thai nha may Ic qui chi Dong Nai ciia vgt lifu chitin va Chi-g-PAN/A
Vat lifu Chitin
Chi-g-PAN/A
Mau thu NMG NMD NMX NMG NMD NMX
pH 3 3 6-7
3 3 6-7
Nong dg Pb'" trudc hap phy, mg/l
137 65,2 0,48 137 65,2 0,48
Nong dg Pb'" sau hip phy, mg/l
56,7 23,3 0 35
0 0 Can bang hip phy Pb'" cua cae miu Chi-g-
PAN/A dugc khao sat trong viing nong dg cua dung djch muoi Pb(N03)2 tir 100 250 mg/l, sau 24 gid, trong moi trudng pH = 7. Ket qua cho thiy lugng chi hap phy da tang theo nong dg ban diu va dgt gia trj bao hoa tgi nong dg khoang 200 mg/l. Kha nang hip phy ion kim logi vdi dung lupng cao cua chitin bien tinh la do sy co mat cua mpt so lupng Idn nhdm ua nude cung nhu cau triic "linh hogt" ciia chudi polyme chitin, thich hgp cho sy tgo phiirc vdi ion kim logi [3].
Moi lifn hf giira dung lugng hap phu Q (mg/g) va nong do eua ion Pb'" sau khi hap phu dugc mo ta
bdi phuong trinh Langmuir [7]. Sy lya chgn nay la thich hgp vl do thj tuyen tinh va hf sd tuong quan R'
= 0,988. cac gia trj Q va b cd the xac djnh dua tren do thj bieu dien C/Ye theo Ce, theo do dung lugng hip phy eye dgi Q = 59,17 mg/g (hay Q = 0,286 mmol/g) va hf so b = 0,299 1/mg. Dung lugng hap phy ion Pb'" cua Chi-g-PAN/A la tuong duong vdi vat lifu chitosan hifn tfnh ghep copolyme ciia poly(acrylonitrin) Ifn chitosan khau mgeh vdi epyelorohydrine [10]. Difu nay chiirng to ring, vat lifu Chi-g-PAN/A eo nhieu tifm nang iimg dyng xir ly nude thai cdng nghifp, dgc bift la nudc thai nha may san xuat pin, ac qui.
120
60
•s. 50
^ E 40
^ 30
20 10
• •
•
• •
•
•
1.6
50 100 150 200 250 300 C.(mgfl)
y=0.0169x +0.0566 R= = 0.9881
20 40 60 80 Ce(mg/l)
LTmh 4: Hap phy Pb cua Chi-g-PAN/A: (a) Anh hudng cua pH den kha nang hap phy Pb' (b) Hip phy Pb'" theo nong dg, (c) Dgng hgc hap phy Langmuir
4. KET LUAN
Chitin amidoxim dugc che tgo tir sy chuyfn hda chitin ghep aerylonitrin bang phuong phap chieu xa trudc, bdi tac nhan hydroxylamin. Nhung dgc trung vf cau tnic cua vat lifu trudc va sau khi bien tinh qua anh chup SEM va phep phan tfch nhift, chung td qua trinh ghep va chuyen hda da thyc hifn thanh cdng, thuan lgi cho qua trinh hap phy.
Vimg pH toi uu cho sy hip phy Pb'" la pH ^ 7.
Dudng ding nhift hap phy thich hgp vdi phuong
trinh Langmuir va dung lugng hip phu dugc xac djnh vdi Q = 0,286 mmol/g. Thir nghifm hip phu Pb "tir nudc thai nha may Ic qui chi Dong Nai cung da dugc thyc hifn. Cdng trinh nay cung d p so lieu hiru ich ve sy tach Pb'" tir nudc thai cdng nghifp.
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TCHH, T.49(4), 2011
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Lien he: Nguyen Quoc Hien
Trung tam Nghifn ciiu va Trien khai Cdng nghf Biic xg, VAEC 202 A, dudng 11, phudng Linh Xuan, qugn Thii Diic
Thanh pho Hd Chf Minh
Email: hien7240238(^yahoa.eom.