TAP CHI HOA HOC T. 49(3)347-351 THANG 6 NAM 201
T 6 N G
Hgp VAT LIEU MAO QUAN TRUNG BJNH SBA-15 CHLrA NHOM THIOL (-SH) VA HOAT TJNH HAP PHU ION Pb^*
TRONG DUNG DjCH NU'OC
Hoang Van Diic', Nguyen Thj Anh Thu', Pham Duy Thmh", Dang Tuyet Phuong\ Nguyen Huu Phii' Trucrng Dgi hc)c Sir phgm - Dgi hoc Hue
' Trucrng PHTH Td I an On - Khdnh Hda
"' I Vc'" Hod Hpe-1 'ien Khoa hpe vd Cdng nghe/ I 'ic''! Nam Ddn Tda soan 23-12-2010
Abstract
Mesoporous thiol-functionalized SBA-15 silicas (HS-SBA-15) have been directly synthesized by co-condensation of tetraethyl orthosilicate (TEOS) and 3-mercaptopropyllrimethoxysilane (MPTMS) with triblock copolymer P123 as- stmcture-directing agent under hydrothermal condition. The sample was characterized by EDX. IR and N^ adsorption- desorption measurement. The sorption behaviors of Pb" on the sample were studied. Freundlich isotherm was found to describe the sorption data better than Langmuir isotherm and pseudo second order kinetic model could fit the rate equation of that Pb"~ad sorption on HS-SBA-15 solid.
MO DAU 2. THUC NGHIEM
O nhiem kim loai nang la mdt van de mdi trudng phd bien va dang la mdi quan tam cua nhieu qudc gia tren the gidi v i cac ion kim loai nang tan trong nudc cd the dugc tich luy dan trong chudi thirc an va vi vay trd thanh mdt yeu td nguy hiem den siic khoe con ngudi. Viec nghien ciru tim ra cac pbuong phap loai bo va thu hdi kim loai nang tir cac ngudn nudc dang thu hiit su quan tam cua nhieu nha khoa hgc.
Nhieu phuang phap khac nhau dugc su dung de xu ly nudc thai chira kim loai nang da dugc cdng bd trong nhiing nam gan day nhu: su khu. su ket tua, ddng ket tua. tham thau ngugc, trao ddi ion, dien phan. hap phu.... Trong cac phuang phap dd hap phu la mdt trong nhirng phuong phap bieu qua va kinh te nhat nen dugc su dung rdng rai trong xu li nudc thai. Nhieu loai chat hap phu khac nhau cung da dugc sir dung de hap phu cac ion kim loai nang nhu: than boat tinh, zeolit, khoang set...[l]. Va gan day vat lieu silica mao quan trung binh (MQTB) (HMS, MCM-41...) dugc bien tinh vdi cac tac nhan khac nhau dugc sir dung ngay cang tang nhu la mdt chat hap phu trong xii' li nudc thai vi cd do chgn lgc cao ddi vdi cac ion kim loai, dac biet la khi bien tinh be mat ciia cac vat lieu nay bang cac nhdm chirc huu ca thich hgp [2].
Trong bao bai bao nay, vat lieu MQTB SBA-15 bien tinh vdi nhdm thiol (-SH) da dugc thuc hien bang phuang phap tryc tiep. Tinh chat hap phu cua vat lieu SBA-15 biSn tinh ddi vdi ion Pb"^ trong dung djch nudc ciing da dugc khao sat.
Vat lieu SBA-15 bien tinh bang nhdm thiol dugc tdng hgp bang phuang phap thuy nhiet true tiep tuong tu nhu tdng hgp SBA-15 [3] tir cac hda chat ban dau la: tetraetyl orthosilicate (TEOS).
3-mercaptopropyltrimethoxysilane (MPTMS). chat dinh hudng cau true (DHCT) P123 (pluronic) E02()P07oE02i) va axit HCl. Qui trinh dugc md ta nhu sau: 2g P123 dugc hda tan vao 75 ml HCl 2 M den dung dich trong sudt. Tiep theo 4.5 g TEOS dugc them vao dung dich va khuay manh o 40"C.
Sau 30 phut, 0,693 g MPTMS dugc them vao hon hgp va tiep tuc khuay manh trong 2 gid, rdi khuay nhe trong 24 gid'. Sau dd hdn hgp sol-gel dugc lam gia a 100"C trong 24 gid. Ket tua dugc lgc, rua va sav' 0' 70"C trong 24 gid. Sau dd, ket tua dugc soxblet trong etanol 72 gid de loai bo chat DHCT.
San pham dugc ki hieu la: HS-SBA-15.
cac phuong phap dac trung mau tdng hgp:
Dudng dang nhiet hap phu-kbu hap phu N; dugc do o' 77K tren thiet bi Ommisorp-100. Phd hdng ngoai (IR) trong viing tir 4000 400 cm"' dugc ghi tren mav IR-Prestige-21(Shimadzu) va phan tich nang lugng tan xa tia X (EDX) dugc ghi tren mav JED- 2300, JEOL.
Tinh chat hap phu cua mau HS-SBA-15 dugc khao sat qua su hap phu ion Pb"' trong dung dich nudc. Ndng do Pb'~ dugc phan tich bang phuong phap Von-Ampe hda tan anot vdi ky thuat ghi ddng xung vi phan (DP) diing dien cue giot thuy ngan treo (HMDE).
TCHH.T. 49(3). 2011 Hodng Vdn Dire va cdngsu
3, KET QUA VA THAO LUAN
1
Ket qua phan tich nguyc-n td bang I.DX cho thay su tdn tai cua ciic nhdm thiol trong vat lieu bicn tinh vdi tl le mol MPTMS TLOS =^).124. Ti le mol MPTMS/TEOS danh giii biing phuong phap phan tich nguyen id thap ban so vdi ti lc dd o' trong bdn hgp ban dau (0.1 74). dieu nay cd lc do mill mdt phan nhdm SH khi xu li soxhlcl. Tuv nhicn. lugng MPTMS vao trong mang cau tnic vat lieu SBA-15 trong nghien ciru cua chimg ldi cimg tirong tir nhu ket qua cua cac liic gia khac [1.4].
Sir tdn lai cua nhdm thiol con dirge khiing dinh them bang phd IR. Phd FT-IR cua man IIS-SBA-15 dugc ghi lir 400 den 4()()(i cm ' va dugc trinh bay IT hinh I. Mdl dao ddng veu dugc quan sal o 2571 cm ' dugc qui cbo dao ddng bien dang cua nhdm Sl I [5].
Cim triic MQTB iral tu cua vai lieu llS-SHA-15 dugc nghien ciru bang dang nhicl hap phu va khu hap phu N:. Hinh 2 trinh bav dang nhiet hap phu va khu hap phu N: cua mau HS-SBA-15 va cua SBA-
15. Nhan thav' rang, tat ca cac duong dang nhiet thu dugc cua mau HS-SBA-15 cung nhu SBA-15 deu thudc loai /L theo phan loai lUPAC [6]. hinh dang cua cluing dac trung boi su hap phu da ldp ciing vdi
su ngung tu mao quan trung binh. Do ddc dang nhiet cd khuynh hudng chuyen ve cac gia tri ap suat tuong ddi thap ban khi chuyen tii' SBA-15 qua mau HS- SBA-15 cho thay dudng kinh mao quan cua mau IIS-SBA-15 nho ban cua SBA-15. Cac dac trung xdp tinh loan tii' dang nhiet hap phu va giai hap nita cho thay, dic'n tich be mat giam tir 587 xudng 543 nr/g cung vdi sir giam the tich Id xdp 0.65 den 0,58 cmVg, duong kinh mao quan giam tir 64.2 den 50.2 A cimg su tang thanh mao quan tir 57.8 den 74.7 A khi c() mat cua cac nhdm thiol trong tudng mao quan. Sir thay ddi the tich mao quan. kich thudc mao quan va chicu day tuirng mao quan cd the dugc giai thich nhu sau. Cac nhdm mcthoxy cua MPTMS co the ngirng lu ddng thiri voi TLOS dc hinh thanh nen mang ciiu triic vd ccr. cac chudi mcrcaptopropyl co the tuong tac vdi cac nhdm ua nudc cua chat DHCT P123 bang cac lic'n ket hidro va tao nen cau triic dugc sap xep trat tu. Khi loai bo chat DHCT. cac chudi mcrcaptopropyl co the tai sap xep de hinh thanh cac nhdm chirc huu co vuon ra tir tudng vo ca vao trong cac kenh mao quan. ket qua la mdt phan khdng gian ben trong cac mao quan da bi chiem.
ddng thdi gia tang dan chieu day tuong mao quan [7].
1 I
So song (cm ')
Hinh 1: Phd FT-IR cua mau HS-SBA-15 tdng hgp
Kha nang hap phu ion Pb'" tii' dung dich nudc cua mlu HS-SBA-15 tdng hgp dugc danh giii trong dieu kien sau; nhiet do 3 0 T ; pH dung djch 5.5; ciic dung dich Pb"' ndng do khac nhau tii' 30 den 110 mg/l dugc pha tii' mudi Pb(CH,,COO):.H:0; the tich dung dich Pb"" lay cho moi lln thi nghiem (V) la
150 ml; khdi lugng chit hip phu (HS-SBA-15) moi lan thi nghiem la: m = 0,05 g. Dung lugng hip phu (DLHP) (q,) dugc tinh theo cdng thirc sau:
d, =
(C^^-C,)V m
Trong dd: G, va C, la ndng do ion kim loai ban dau va tai thdi diem t. mg/l.
Hinh 3 trinh bay DLHP theo thdi gian vdi cac ndng do ion Pb"' ban dau khac nhau (30 110 mg/l).
Ket qua cho thay rang, DLHP tang khi ndng do ban dau cua Pb"' tang len va qua trinh hip phu xay ra nhanh o trong khoang 20 phut diu tien (dat khoang
TCHH, T. 49(3), 2011
hon 90% so vdi DLHP luc can blng), sau dd qua trinh xay ra cham lai va dat can blng khoang tii' phut 4(). Tdc dg hap phu xay ra nhanh cung cho thiy su tiep can de dang ciia cac ion Pb"" vdi cac nhdm -SH, hay ndi each khac nd cung gian tilp cbo thiy sd lugng nhdm -SH. su phan bo nhdm -SH tren hk mat cung nhu su ddng nhat cac kenh mao quan cua vat lieu HS-SBA-15 la rit cao.
Ddng hgc hap phu la mdt bd thdng sd quan trgng trong viec ap dung cac qua trinh bap phu vao xu ly nudc, boi vi ddng hgc hap phu cd the dugc su dung de du doan tdc do tach loai chat d nhiem khoi dung dich nudc trong thiet ke cdng trinh xir lv nudc blng
Tdng hpp vdt lieu mao qudn...
phuong phap hap phu. Tuy nhien, cac tham sd ddng hgc thuc (intrinsic adsorptive parameters) rat khd xac dinh, vi qua trinh hap phu kha phiic tap, bj anh hudng nhieu yeu td: khuech tan, ban chat cau true xdp, thanh phan hda hgc ciia chat hap phu,.... Do dd, hien nay ngudi ta thudng irng dung cac phuong trinh ddng hgc hinh thirc de xac djnh cac hang sd tdc do bieu kien. Trong phim nay, hai md hinh ddng hgc thudng dugc sir dung nhat de nghien cii'u ddng hgc cua sir hap phu kim loai da dugc sii' dung, dd la:
phuong trinh ddng hgc bieu kien bac nhat (the pseudo-first order) va phuong trinh ddng hgc bieu kien bac hai (the pseudo-second order) [5, 8].
.^••••,•«•>«"'
Hinh 2: Dudng dang nhiet hap phu-kbu hap phu N^ cua SBA-15 v a n "BA-15
120 100 80
60
40
= 20 C
- .^0 mg/l - 5 0 mg/l - 80 mg/l - llOmg/1
20 40 60 80
1 (phut)
100 120
Hinh 3: Dung lugng bap phu theo thdi gian d cac ndng do Pb~" khac nhau
Phuang trinh ddng hgc bieu kien bac nhat dang tuyen tinh dugc bieu dien dudi dang:
\n(q^-q,) = \n{qj-kj (1) Phuang trinh ddng hgc bieu kien bac hai dang tuyen tinh dugc bieu dien dudi dang:
+ • (2)
q, k._q; q^.
Trong dd: q^.: la DLHP tai thdi diem can bang, mg/g;
q,: la DLHP tai thdi diem t. mg/g; k\: la hang sd tdc do hap phu bieu kien bac nhat (phut'); k^- la hang sd tdc do hap phu bieu kien bac hai (g/mg.phiit).
Hdi qui tuyen tinh cac gia tri (qc-qO vdi t theo phuang trinh (1) ddi vdi md binh bieu kien bac nhat, va cac gia tri (1/qt) vdi t theo phuong trinh (2) cua md hinh bieu kien bac 2. Tii' cac gia tri do ddc va doan cat vdi true tung cua cac dudng tuyen tinh ta tinh dugc cac hang sd ddng hgc k\ va ki. Muc do tuyen tinh cua cac gia tri thuc nghiem theo md hinh dugc danh gia blng he sd tin cay Pr Ket qua cac tham sd ddng hgc va blng sd tin cay dugc trinh bay
o bang 1. Nhan thay rang cac he sd tin cay ciia md hinh bieu kien bac hai Idn ban nhieu so vdi bac nhat va gan vdi dan vi. Ket qua nay cho thay, md hinh ddng bgc bieu kien bac hai md ta tdt ban qua trinh hap phu so vdi md hinh bieu kien bac nhat. Ket qua nay ciing phii hgp vdi cdng trinh nghien cim su hap phu ion kim loai Ien vat lieu HS-MCM-4I [5].
Trong nghien ciiu nay, hai md hinh dang nhiet hap phu phd bien nhat la md hinh dang nhiet Langmuir va Freundlich ciing da dugc sir dung de nghien cuu dang nhiet hap phu.
Phuang trinh dang nhiet Langmuir dang tuyen tinh nhu sau [8]:
<?. = d,
"\ + K^C,. hay — - — 1 d. + -
1,n ^idn
c.
(3)Phuong trinh dang nhiet Freundlich dang tuyen tinh nhu sau [9]:
d. = K,Cl
I H hay In q^, = In AT^, + - In C, (4) nTrong dd: q,, la DLHP tai thdi diem can bang (mg/g);
q,„ la DLHP cue dai (mg/g); Ce la ndng do chit bi hap phu tai thdi diem can bang (mg/l); KL la hang sd
T C H H . T . 49(3), 2011 Hodng Van Dire vd cdng su hip phu Langmuir (l/mg) dac trung cbo ai luc cua Langmuir. va In^e vdi InC, ddi vdi md hinh tam hip phu; A'/ (1/g) va \/n la ciic blng so Freudlich. Tir cac gia tri do ddc va do^n cat cua true Freundlich. ^'-"''S ^^ ^'"h ^'•'d'; cac gia tri tham sd cua phuong
Hdi qui tuyen tinh l/(/, vdi 1/C, doi vdi md binh trinh ddng hgc. Ket qua trinh bay o bang 2.
Bang I: Mdt so tham sd cua phuang trinh ddng hgc bieu kien. hap phu Pb" tren HS-SBA-15
Ndng do. mg/l
30 50 80 110
1
R-
0.S20 0.(i43 0,867 0.S02
Ddng
phiit ' 0.037 0.030 0.020 0,019
hoc bac 1
mg/g 16.54 14.57 16,54 13.65
dLr
mg/g 57.17 66,5 1 87,41 107.66
R-
o.oox
0.999 0.999 0.999
Ddng hgc bac 2 A-2 X10"-^
g/mg.phiit 5.78 6.77 5.50 5.40
^'..cxp.
mg/g 58,82 71.43 90.91 111,11
2
" c . e x p '
mg/g 57.17 66.51 87.41 107.66 (/' : gia trj DLFIP ciin bang linh theo phuong trinh dong hyc: cp ^^
none do can hanu.
gia tri DLHP can bang tinh lu ndng dp dau va
Bang 2: Cac Dang nhiet
Langmuir Freundlich
gii 1 tri tham sd cua phuong trinh dang q,,! (mg/g) Kl hoac Kf
111,11 0.1233 29,0495
nhiel Langmuir va Freudlich R"^
0.831
3.380S 0.929 Tir ket qua bang 2 cho thay rang, dang nhiet
Freundich cd he sd tin cay cao R" = 0.929 va cao ban so vdi he sd tin cay R" = 0.831 cua dang nhiet Langmuir. Do dd, cd the cho rang qua trinh bap phu ion Pb'^ tren HS-SBA-15 tuan theo dang nhiet Freundich tdt ban dang nhiet Langmuir. Ket qua nav Cling tuong tu ket qua cua Lam va cdng su [9] khi su dung vat lieu HS-MCM-41 de hap phu vimg. Ket qua bang 2 cung cho thay do hap phu dat giii tri cao la I l l m g / g o 3 0 T . So vdi cac chat hap phu khac nhu cao lanh (do hap phu: 31.75 m g g [10]) hav bentonite (do hap phu: 30 mg,g [II]) thi HS-SBA-
15 cd dung lugng hap phu vugt trdi. Tir cac kel qua tren cd the bieu dien kha nang hap phu ion Pb" cua vat lieu HS-SBA-15 theo phuong trinh sau:
q =29.0495.C ''""'^ =29, WArC;"'"''
4. KET LUAN
Vat lieu SBA-15 bien tinh blng nhdm thiol da dugc tdng hgp thanh cdng bang phuong phap ddng triing ngung. Ket qua dac trung cho thiy ring mau tdng hgp van duy tri dugc clu triic luc lang hai chi^u trat tu, kich thudc mao quan ddng deu. Tu\ nhien gia tri ciia cac tham sd dac trung cho clu triic vat lieu cd thay ddi so vdi SBA-15 khi cd mat cua cac nhdm thiol trong mau. Cu the la khi cd mat cua cac
nhdm thiol thi dien tich be mat (SHIT) ^a kich thudc mao quan (dp) giam. chicu dav thanb mao quan (t«) tang. Vat lieu HS-SBA-15 the hien kha nang hap phu nit lot ddi v oi ion Pb"' Do hap phu dat gia tri cao. Su hap phu xay ra theo md hinh Freundlich. toe do hap phu tuan theo phucmg trinh ddng hgc phan irng bac 2 bieu kien. Tir cac ket qua dd. cd the thay rang, vat lieu HS-SB.A-L^ la viit lieu cd trien vong trong hiip phu de xu ly va thu hdi kim loai nang (Pb) trong nudc.
TAI LIEL TH.WI KH.AO
1. .1. ,\guado. J. M. .Arsuaga. and .\. Arencibia. Ind.
Eng, e hem. Res.. 44. 3665 36^1 (2005).
2. A. Bibby. and L. Mercier. Chem. Mater.. 14. 1591- 15')-(2002).
3. D. Zhao. Q, Huo. J. Feng, B. F Chmelka and G. D.
Stucky. J. Am. Chem. Soc.. 120. 6024 - 6036 (1998).
4. L. M. \ a n g . V J. Wang. G. S. Luo. \'. V. Dai.
Micropor. Mesopor. Mater., 84, 275-282. 2005.
5. .\. Liang. Y. Xu. G. Sun. L. Wang. Y. Sun. X. Qin.
Colloids and Surfaces A: Physicochem. Eng.
Aspects. 349. 61 -68(2009),
6. Nguyen Hiru Phii, Giao trinh hap phu va xuc tac tren be mat vat lieu vo co mao quan. Nxb. Khoa hpc va Kv thuat Ha Npi (1998).
TCHH.T. 49(3), 2011 Tdng hpp vdl lieu mao quan...
7. Q. Wei, Z. Nie. Y Hao. Z. Chen. J. Zou. W. Wang.
Mater. Letters, 59, 3611 3615 (2005).
8. L.-G. Yan, X.-Q. Shan, B. Wen. S. Zhang. Joumal of Colloid and Interface Science, 308. 11 19 (2007), 9. K. F. Lam. C. M, Fong, K. L. "leung. G. Mckay.
Chem. Eng. J.. 145. 185 195 (2008).
10. A, Sari. M. Tuzen. D. Citak. M. Soylak. J. Hazard.
Mater.. 149. 283-291 (2007).
U . S . Wang. Y. Dong. M. He. L. Chen. X. Yu. Applied Clay Science 43. 164- 171 (2009).
Lien Ige: Hoang Van Diic Khoa Hda hgc.
Trudng Dai hgc Su pham Hue. 34 Le Lgi - Tp. Hue Email: vanduchoaniK^/ vahoo.com.
