TAP c m KHOA HQC - BAI HQC BONG NAI, SO 01 - 2016 ISSN 2354-1482 NGHIEN c u t ) KHA NANG LOAI BO CHI KHOI DUNG DICH NU*6C BCtt VAT LIEU NANO MANGAN DIOXIT: NGHIEN CUtJ
CAC MO HINH p m TUYEN TINH
ThS. Binh Van Phuc*
PGS.TS. Le Ngpe Chung^
SV. L^i Thi Le Xuan' PGS.TS. Nguyin Ngoc Tuan"*
TOMTAT
Trong nghien cieu ndy, vdt lieu nano gamma — Mn02 dugc dung ldm chdt hdp phu di logi bd ion Pb^* tir dung dieh nu&c. Cdc yiu td dnh hudng din khd ndng hdp phu cda vdt lieu nhupH, thai gian hdp phu vd ndng dp ban ddu cua Pb (II) da duac khdo sdt. Du lieu thuc nghiim da duac phdn tich b&i 3 phuang Pinh hdp phu ddng nhiet phi tuyin la: Langmuir, Freundlich va Sips. Kit qud nghiin cuu cho thdy, dung luang hdp phu tdi da duac tinh tir md hinh ddng nhi^t phi tuyin Langmuir la 197.64 mg/g & 297K vd pH = 4,0. He s6 tuang quan R^ linh tie phuang trinh Sips (R
=0.9635) cao han so v&i hi sd tuang quan R^ tinh tir phuang Pinh Langmuir (R
=0.9623) vd Freundlich ((R^ =0.8593) cho thdy, qud trinh hdp phu tudn theo ddng th&i cd hai md hinh Langmuir vd Freundlich.
Twkhda: chi, hdp phu, md hinh ddng nhiet, gamma-Mn02- 1. Dat van de
Chi la kim loai nang dugc sir dyng rfing rai trong nhieu nganh cfing nghifip quan trpng nhu pin, san xudt va in an cac chat mau, nhien lieu, vat lieu nhifip anh va san xudt thufic nfi. Chi la mgt trong ba kun loai nang dpc hai nhat, cfi thfi la nguyen nhan gay ra nhifiu vdn dfi vfi siic khfie, dac biet cfi thfi gay ra tir vong cho con ngufii (xem thfim [1]).
Cfi rdt nhieu phuong phap dS dugc ap dung d^ loai bfi ion chi (II) tir cac vung nufic bi fi nhifim nhu kfit tua hfia hpc, hdp phy va trao dfii ion, cflng nghe mang va dung dung moi ehifit. Hdp phu dugc coi la mfit trong nhimg phuong phap hieu qua nhdt va ddy hiia hen dfi loai bfi lugng vfit cac ion kim lo^i nang vi hieu qua lam giau cao va dfi dang trong giai doan t^ch.
Gdn day, tinh chdt hdp phu cua cac oxit kim loai cfi cau true nano da dugc ap dung cho xir ly fl nhifim mfli trufing bfii vi chung cfi dien tich bfi mat lon va cfi nhieu nguyfin tii khong bao hoa trfin be mat lam tam hap phy, do dfi lam tang kha nang hap phy dfli vfii cac ion kim loai manh. Oxit mangan co cdu true nano da thu hiit su chu y 'Truimg D^i hoc D6ng Nai.
frudng Dai hpc Dk L?t.
^Tnrimg Dai hoc D6ng Nai.
Vifin Nghien ciiu Hat nhSn Di L^t.
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TAP CHJ KHOA HQC - BAI HOC BONG NAI, SO 01 - 2016 ISSN 2354-1482 ngiy cang nhifiu vi iing dung cua nfi trong nhieu linh vuc khac nhau nhu trong san xudt pin, chat xiic tac, va vat lieu hap phy.
Trong nghifin ciru nay, chiing tfii da sii dyng v^t lieu gamma-NfoOz cau tnic nano (y - MnOj) iam vat heu hdp phy dfi loai bfi ion Pb (D) tir dung dich nudc. Kha nang hdp phu cua vat heu MnOi va hifiu sudt loai bo ion Pb (II) tir dung dich nufic dupc danh gia bdng each sii dyng ba mfi hmh ddng nhiet FreundHch, Langmuir va Sips.
2. Hfia chdt, thiet bi, dung cu va phuong phap nghien ciru 2.1. Hda chdt
Cac hfia chdt sir dung dfiu thuoc loai cfi dp sach phan tich (PA)
- Axit nitric HN03(d=l,35g/mI) nflng dfl 65%, PA, Merck, Natri hidroxit NaOH, PA, Merck.
- Chi nitrat Pb(N03)2, PA, Merck va mau chuan don va da nguyen tfl (multi - elements standard for AAS), cua hSng Merck.
- V|it lieu hdp phu gamma - MnOj cau tnic nano dugc tfing hgp tai Vifin Nghifin cim Mfii trufing, trufing Dai hpc Da Lat, Viet Nam.
2.2. Dung cft
- cac dung cu thliy tinh: cfic, binh tam gidc, binh dinh miic, pipet, micropipet cac loai 1-25^1, 50 pi, lOOfil, 500 ^I, 1000 (ti cua cfing hoa Lifin bang Diic.
- cac ong nghiem Polyetylen (P.E) dung mlu
- May quang phfl hap thy nguyfin hi AA - 7000 cua hang Shimazu, san xudt tai Nhat Ban, trong dfi, dfin Cathode rSng iing vfii nguyen tfl Pb hdp thy o buoc song X
= 283.3 nm.
- Can phan tich cfi dfl chinh xac 10"'^ gram, san xudt tai Thyy Sy - Tii sdy SheLab cua Vuong Quoc Anh
- May khudy tit da difim cfi kifim soat nhifit dfl (Model Kika R5) - May li tam (Germany)
- May do pH (Mi-150 Romania)
- May quang phfl hdp thy nguyen tii AA - 7000 (Shimadzu, Nhat Ban) 2.3. Phwffngpkdp ngkien ciru
- Hap phy tmh: 50 ml dung dich Pb^^ dugc cho vao Bacher cfi chiia 0.1 gam vat lieu hap phy. Cac yfiu tfi anh hufing dfin qua trinh hdp phu ldn lugt dugc khao sat:
thfii gian hdp phy (20 -^ 240 phut), pH ciia dung dich (2-^6) va nflng dfi ddu ciia dung dich Pb^"" (100^500 mg/1) Cac tin nghifim dugc tifin hanh fi nhi?t dp phfing (24 ± 1 C), hfin hpp hdp phy dugc ldc bdng may ldc voi tfle dfi 240 vfing/phiit.
- Hon hgp thu dugc sau qua trinh hdp phy dugc ly tam fi 5500 rpm de cho cac hat Mn02 tao mang va kfit dinh voi nhau, sau dfi Ipc tdch cdn than ldy dich Ipc bdng bfl lgc PTEE. May quang phfi hdp phu nguyen tii AA - 7000 dugc sii dung dfi xac dinh nflng dp cua ion kim loai truo'c va sau qua trinh hdp phy.
- Kha nang hdp phu duoc tinh theo cfing thiic sau:
q,-.(2.Z£s)L (1)
m 66
TAP CHI KHOA HQC - BAI HQC BONGNAI, SO 01 - 2016 ISSN 2354-1482 Trong dfi, qe la dung lugng ion kim loai bi hdp phy (mg/g) tai thfii diem can bang; Co va Ce la nfing dp chi tai thfii diem ban ddu ban dau va thoi diem can bang (mg/L); V la the tich cua dung dich (L) va m la khfli lugng c^a vat lifiu hdp phu sii dung (g).
3. Ket qua va thao luan
3.1. Thupc tinh cua vdt liiu kdp pku Y-Mn02
cau tnic va thuflc tinh be mat cua vat lieu MnOi dugc phan tich bdng nhilu xa tia X (XRD), SEM va BET. Ket qua phan tich cho thay MnOi cdu tnic nano gamma, kich tiiufic khoang 10 - 18 nm va dien tich bfi m^t BET la khoang 65 m^/g (xem tiiem [2-3])-
Hinh 1. Nhieu xa tia X cua vat lifiu (a) va anh SEM cua vat lieu (b) Bang 1. Kfit qua phSn tich B.E.T and B.J.H
y - MnOi
Pore size BJH Adsorption
417.8 A
BJH Desorption
340.2 A
Surface Area BET
Surfece 65.00 mVg
BJH Adsorption cumulative surface area
71.04 m'/g
S.60 •
i"«•
^ 20
0 5
p H (a) 3.2. Cdc yiu t6 dnh hu-dng din qud
trinh hdp phtf
3.2.1. Anh hudmg cita pH pH la mOt trong nhfing yeu to anh huong true ti6p dSn kha nang hap phu cac ion kim l o ^ nang. Anh huong cua pH dfa kha nang h i p phu Pb^* dugc biiu diln qua hinh la. K6t qua cho thay, khi pH cua dung dich tang ISn tit 2 din 6, kha
nang hSp phu Chi (II) cung tang len va dat dSn bao hoa tai pH = 4. Vi Iy do nay, gia tri pH t6i uu dugc chon la pH = 4.0. Kha nang h i p phu cac ion Pb^ * khi pH tSng c6 the dugc giai thich ring, g pH cao hon, bg mat vat lieu hSp phu dugc dS proton hoa.
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(b)
d o dfi t a o difiu kifin t h u a n l g i c h o q u a t r i n h h a p p h u c a t i o n k i m l o a i . T u y n h i e n , tai p H
> 6.0, P b (II) t a o kfit t u a P b ( 0 H ) 2 , d o dfi k h a n a n g h a p p h y s e g i a m xufing.
3.2.2. Anh hu&ng cua thai gian hdp phy Mfii q u a n h e g i u a thfii g i a n h a p p h y v a k h a n a n g h d p p h y Pb^^ ciia v^t l i e u y- M n O i d u g c thfi h i e n t r o n g h i n h 2 b . Tir ket q u a t h u d u g c , rS r a n g la k h a n a n g h a p p h y i o n Pb^"^ t a n g k h i t h o i g i a n tiep xiic t a n g l e n . K h a n a n g h d p p h u ion Pb^^ ciia v a t l i e u y- M n O a d a t c a n b d n g t r o n g thfii g i a n 8 0 p h u t v o i 9 2 , 4 7 % P b ^ ^ h i h d p p h y .
3.3. Nghiin cdn kdppkff dang nkiit Cac mfi hinh hdp phy dang nhifit la cdc mfl hinh todn hgc dfi mfl ta sy phan bfi giua chdt bi hap phu (pha long) vk chat hap phu (pha rdn), dya tren gia dinh rang lien quan den su khfing dfing nhdt/dfing nhat cua bfi mat ran va kha nang tuong tac giiia cac chat bi hdp phy. Trong nghifin ciiu rmy, dil lifiu thyc nghifim dugc phan tich bang ba mfi hinh phi tuy^n Langmuir, Freundlich va Sips (xem thfim [4]).
3.2.1. Md hinh hdp phu ddng nhiet Langmuir [7-16]
Langmuir gia dinh rdng: bfi mat cua vat lieu la dong nhat va sy hdp phy trfin bfi mat v£it lieu la don lfip, khflng cfi su tuong tac giOa cac phan tii chdt hi hdp phy. Mfl hinh dufing dang nhiet Langmuir dugc dimg dfi dy doan kha nang hap phy toi da tao thanh dem Ififp trfin bfi mat vat lieu.
Dfl till bifiu thi mfii lifin h? giiia qe (mg/g) voi nflng do can bdng Ce (mg/L) ciia Pb "^ dupc the hien trong hinh 3 a va cdc
0 100 , 200 300 Thdi gian t i ^ xuc (jfixiiX) Hinh 2. Anh huong ciia pH va thfii gian dfin kha nang hap phy cua y- Mn02
2ZS.0 IBS.O
% iD5.a tiSO
(a)
- • - E x p e m n e i i t —•-LMigmmi ID 40 . ^ «0 SD
Ce(m(/l! IDD
160
B
40
(b)
- • - E x p e n m e n t - • - F r e i m d i i e h
Hinh 3. Dfl thi dang phi tuyin tinh cua mo hinh Langmuir (a);Freundlich (b) va Sips (c)
TAP CHI KHOA HOC - BAI HOC D 6 N G NAI, SO 01 - 2016 ISSN 2354-1482 thfing sfi dufing dang nhiet phi tuyfin tinh, qm, KL va he sfl tuong quan R^ dugc thfi Men trong Bang 2.
Ket qua tfnh toan cho thdy, kha nSng hdp phii toi da trfin hk mat vat lieu cua Pb "^
la 197.64 mg/1. Gia tri cao cua hfi s6 tuong quan R^ (R^ = 0,9623) cho thdy su tiifing nhat cao gifla cac gia tri thyc nghifim voi mo hinh.
3.2.2. Mo kinh hdp phu ddng nhiet Freundlich
Mfi hinh ddng nhiet Freundlich dugc lua chgn dfi danh gia cuong do hap phy Clia chdt bi hdp phy tren bfi mat vat lifiu hdp thy. Mfi hinh ddng nhifit Freundlich (Freundlich (1906)) la mgt phuong hrinh thuc nghiem dya trfin su hdp phu trfin bfi mat khflng dong nhdt ciia vat lifiu.
Dfl thi cua phuong trinh hap phy ddng nhifit Freundlich dugc bieu thi trong hinh 3b va cac thflng sfl ciia duong ddng nhifit dugc thfi hifin trong bang 2. Gia tri 1/n tinh toan dugc la 0,0643 < 1 khdng dinh tinh khong dflng nhat cua bfi mat chat hap phy, dfing thfii dy dodn dugc lien kfit giiia chdt hdp phu va chat bi hap phu la hen ket yeu.
3.2.3. Mo hinh hdp phu ddng nhiit Sips Mfi Mnh ddng nMet Sips la m^t mfi hinh 3 tham so, ket hgp giiia mfl hinh ddng nhifit Langmuir va mo hinh dkn% nMet Freundlich. De tim c ^ gia tri Ks, tts va Ps cua phuong trinh chiing tfii sir dyng chiic nang Solver - Add in cua phdn mfim Excel. Dfl thi cua mfl Mnh ddng nMet Sips va cac thfing sfi Clia mfi hinh dugc thfi Men trong Mnh 3c va bang 2.
Tir kfit qua tinh toan, voi he sfl tuong quan (R^ = 0.9635) ciia mfl hinh dang nMet Sips cao hon so voi h? so tuong quan R^ dugc tinh tir hai mfi Mnh Langmuk va Freundlich cho thdy, su hdp phu ion Pb^"" trfin bfi mat v$t lieu gamma - MnOj tuan theo dong thoi ca hai mfl Mnh Langmuir va Freundlich.
Kfit qua ph&i tich thflng kfi cOng cho thdy, gia tri RMSE (Root mean square error) va CM-square Test (x^) tinh tut mfl hinh Sips < Langmuir < Freundlich khang ding rang du lieu thuc nghifim phu hgp voi mfl Mnh Sips hon mfl Mnh Langmuir va mfi Mnh Freundlich.
Bang 2. Cac thfing sfi cua 3 mfl Mnh pM tuyfin Langmuir, Freundlich va Sips
Mfl hinh
Langmuir
Freundlich
Sips
DangpM tuyen
' 1+KL.C.
q,= Kp.Cj*
Thong so mo
h i n h KL q-Cmg/B)
RMSE R'
x'
1/n Kp RMSE
R=
x'
K.
OL.
P.
RMSE R' l'
2.0038 179.64 3.8824 0.9623 0.3878 0.0643 138.55 7.4986 0.8593 1.5258 333.28 1.8689 1.1754 3.8181 0.9635 0.3620
TAP CHI KHOA HQC - BAI HQC BONG NAI. SO 01 - 2016 ISSN 2354-1482 4. Ket Iuan
Kfit qua ngMfin ciiu cho thdy, y - MnOi cdu tnic nano cfi thfi dugc su' dung dfi loai bfi Pb (II) trong nuoc thai. Du lieu thuc ngMem da dugc mfi ta bfii ba mo Mnh ddng nhifit: Langmuu, Freundlich, Sips, trong dfi mfl hinh Sips mfi ta tot nhat voi he sfl tuong quan cao (R^ = 0.9635). Dung lugng hdp phu tfli da tinh dugc tir mfl hmh Langmuir la 197.64 mg/g fi 297K, pH 4,0 voi tiifii gian tidp xiic la 80 phiit.
TAI LIEU THAM KHAO
1. Lipmg Deng, Yingying Su, Hua Su, Xinting Wang, Xiaobin Zhu, Sorption and desorption of lead (II) firom wastewater by green algae Cladophora fascicularis.
Journal of Hazardous Materials,U3 (2007), 220-225.
2. Chung N. Le, Phuc V. Dmh, Sorption of Lead (II), Cobalt (II) and Copper (II) ions from aqueous solutions by nanostructured gamma-Mn02, NMEC Proceedings, The second international workshop on nano materials for energy conversion, Ho CM Minh City Nov. 17-19 (2014), 21-33.
3. Dinh Van Phuc, Le Ngoc Chung, Equilibrium Isotherm Studies of Sorption of Pb(II), Co(II) and Cu(II) from aqueous solution onto manganese dioxide (y-Mn02) nanostmcture, Vietiiam Malaysia International Chemical Congress (VMICC 2014), Hanoi Vietnam Nov. 7-9(2014), page 167.
4. K.Y. Foo, B.H. Hameed, Insights mto the modelmg of adsorption isotherm systems. Chemical Engineering Journal, Vo\. 156 (2010), 2-10.
INVESTIGATION OF REMOVAL OF LEAD FROM AQUEOUS SOLUTION BYGAMMA - M n 0 2 NANO MATERIAL: NON-LINEAR MODELS STUDY
In this study, gamma - Mn02 wa,? used as an adsorbent lo remove Pb^'*^ ion from aqueous solution. The influences ofpH, adsorption time as well as Lead (II)
initial concentration were investigated. Experimental data was analysized using three non - linear isotherm models: Langmuir, Freundlich and Sips. Results showed the maximum capacity calculated from non-linear Langmuir model was 197.65 mg/g at 297K and pH = 4.0. Because the corelation coefficent R^ value calculated from Sips model (R^ =0.9635) was higher than R^ values from Langmuir (R^ =0.9623) and Freundlich ((R^ =0.8593) one, it showed that the adsorption followed both Langmuir and Freundlich models.
Key words: Lead, adsorption, isotherm model, gamma - Mn02.
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