TAP CHi H 6 A HQC T. 50(3) 273-277 T H A N G 6 N A M 2 0 I 2
TdNG HOP OXIT HdN HOP CeOj-MnjOj CAU TRUC NANO
VA O A N H G I A K H A N A N G H A P P H U C O A CHUNG D 6 I VdiASEN, AMONI, SAT, MANGAN
Luu Minh Dgi'\ Ddo Ng^c Nhi9m', Dutfng Thj Ljm^
' Vi^n Khoa hgc V^t lifu. Vi^n Khoa hgc vd Cdng ngh^ Vi?l Nam Wi^n Dfa ly, Vi^n Khoa hgc va Cdng nghf Vi^t Nam
Den Tda sogn 23-8-2010
Abstract
The nanostrutured mixed oxide CeOi-MniOj have been synlhesised at low temperature (SSO^C) by the combustion of gel prepared from polyvinyl alcohol (PVA), Ce(N0))4and Mn(N03)3, Ce02-Mn203 characterizations were examined by X-ray diffraction (XRD), scanning electron microscopy (SEM) and BET (Brunaure-Emmet-Teller) measurements.
The phase of CeOj-MnjOs with large specific surface area 65.3 m^/g was obtained at 350''C for 2 hours. The nanostructured CeOj-MujOj has been investigated for removing iron, manganese, arsenic and ammoniac from water The sorption characteristics of the nanostrutured Ce02-Mni03 for AS(V), NH4*, Fe(in), Mn(II) according to the langmuir isotherm. The sorption capacities of nanostrutured CeOi-MnjOs are 57 10 mg As(V)/g; 154.54 mg NH//g;
72.97 mg Fe(III)/g; 60.27 Mn(ll)/g.
Keywords: Nanostrutured Ce02-Mnj03 mixed oxide, polyvinyl alcohol, combustion method, removing iron, manganese, arsenic and ammoniac
I.MCJDAU
Hap phu la mQt ky thuat thich hg^ de xit ly amoni, asen, sat, mangan [1-5]. Vat lieu nano chua cac nguyen to dat hiem chua dugc nghien ciru nhieu.
Vat lieu oxit hon hpp Ce02-Mn203 co cau true nano dugc tong hgp a nhiet dg thap bang qua trinh dot chay gel ciia polyvinyl ancol vai muoi nitrat kim loai. Tinh chat dac trung cua Ce02-Mn203 dugc xac djnh biing phucmg phap nhilu xa tia X, phucmg phap hien vi dien tu quet va phuang phap hap phy vat ly.
Oxit h6n hgp Ce02-Mn203 vcri dien tich be mat rieng 65,3 mVg dugc t6ng hgp 0 350°C trong 2 gio.
Da tiSn hanh danh gia kha nang hap phy cua CeO:- MnjOj cau true nano doi voi amoni, asen, sat, mangan trong dung djch nuac theo mo hinh dang nhiet hSp phu Langmuir. Dung lugng hap phu c^c dai cua Ce02-Mn203 kich cau triic nano la 57,10 mg As(V)/g; 154,54 mg NH//g; 72,97 mg Fe(lll)/g;
60,27 Mn(II)/g.
2. THI/C NGHIEM 2.L Hoa chat, dung cu
Dung dich Ce(N03)4, Mn(N03)2, As(V), NH4OH, HNO3, Hzbj, polyvinyl ancol (PVA), Na2As05, AS2O3, Fe(N03)3 dung dich NaOH d6u c6 dp s^ich phi:r. .• !•
Coc chiu nhi?t 100 ml, 200 ml, binh dinh mirc 25 ml, 100 ml, 250 ml, 500 ml, 1000 ml, pipet, may khuay tir, may do hap thy quang, chen nung, tii say, 16 nung.
2.2. Phuong phap nghien ciru
De danh gia mpt s6 d?c trung ciia vat lieu da sii dung cac thiet bi hien dai: May Siemens D-5000 (CHLB Due) voi buc xa CuK^ buac song X - 1,5406 A; kinh hien vi di?n tir quet (SEM) JEOL- 5300 (Nhat Ban); may SA cua hang CUOLTER (My); may so mau quang hpc (Anh).
Nong dp Mn, Fe, NHi"^ dugc xac dinh bang phuang phap so mau a cac buoc song khac nhau:
Mn voi persulfate d buoc song }. = 525 nm; Fe bang phuang phap phenanthroline a buoc song X = 510 nm; NH4^ bang phuang phap phenol a buac song X.
= 640 nm. Ham lupng asen trong cac mau thi nghi?m dugc xac dinh tren may quang pho hap thu nguyen tit (AAS) ciia hang Shimadzu (Nhat Ban).
Danh gia kha nang hSp phu ciia vat lieu theo mo hinh dang nhiet hap phu Langmuir.
3. KET QUA v A T H A O LUAN 3.L Tong hop vat lieu CeOi~Mn203
Tong hgp vat lieu oxit hon hgp Ce02-Mn203 cau
TCHH, T. 50(3), 2012
tnic nano btag phuang phdp d6t chdy gel PVA theo quy trinh nhu sau: Dung djch mu6i nitrat d^t hiem, Mn(N03)2 duoc t90 gel v6i PVA tan trong nu6c 6 s e c vdi pH = 4 theo tJ 1§ moi kim lopi/PVA = 1:3.
Dung djch dugc khuiy tr^n vd gia nhi^t lifin tyc cho tdi khi mgt gel trong d6ng nh4t dugc hinh thdnh. Gel
Luu Minh Dgi vd cgng s\t dugc ldm gid trong tii sdy 6 120°C, sau d6 dugc nung 6 350°C trong 2 gid. Gidn d6 nhiSu xp tia X vd dnh SEM durgc dua ra 6 hinh I(a,b). Di?n tich b^
m&t dirge xdc djnh bftng phirong phdp BET c6 gid hi 65,3 mVg. .
Hinh 1(a): Gian do nhieu xa tia X Hinh 1(b): Anh SI M ciia Ce02-Mn;03
Vat lieu Ce02-Mn203 thu dugc la oxit hon hgp CO cau tnic nano vai nhieu khoang trong dong nhat.
3.2. Hap phu As(V)tren vat li|u CeOi-Mn203 cau true nano
3.2.1. Xdc dinh thdi gian dat cdn bdng hdp phu dot v&i As(V)
Xac dinh thai gian dat can bang hap phy: 0,05 g mau dugc dua vao binh tarn giac 250 ml chua 100 ml dung dich asen co nong dg 1 mg l\. Lay m;"ui phan tich theo thai gian den khi d^t can bang. KCM qua phan tich dugc chi ra a bang 1.
Qua bang 1, thdi gian d^t can bang hap phu ciia vat li?u CeOi-MniOj cau tnic nano doi vdi As(V) la 120 phut.
3 2 2 Ddnh gid khd ndng hap phy .-ist I) cua CeOr Sln:0:
Thi nghidm dugc li^n hanh nhu sau: 100 ml dung djch As(V) nong dp tir 1 mg/l den 200 mg/l (tir dung djch As(V) chuan) dugc khuay lien tuc vdi 0.05 g \%\ lii-u tren may khuSy tir. Sau 120 phiit tach hai pha va xac djnh nong dg As con l^i trong dung djch. Ket qua phan tich dugc dua ra trong bang 2.
Bang 1:
Thpi gian, phiit Nong dp AS con lai, mg/l
rhoi gian dat can 30 0,75
bang hip phy As(V) tren ciia CeOrMn20j 60
0.55
90 0,3
120 0.15
150 0,15
Nong dp As ban dau, mg/l
1,05 5,00 10,01 25,02
Bdng 2.
Nong dp As con lai, mg/l
0,15 2,10 5,60 15,50
Dung lupng hap phy As(V) tren Ce02-Mn203 Dung lupng hip
phy, mg/g 1,80 5,80 8,82 19,04
None dp As ban dau, mg/l
50,50 100,10 150,50 200,10
Nong dp As con lai, mg/l
34,50 75,50 122,50 171,00
Dung lupng hip phu, mg/g
32,00 49,20 56,00 58,20
TCHH, T. 50(3), 2012
Cac hdng so ddng nhi?t cua qud trinh hap phy As(V) tren v§t Ii?u CeOi-MuzOs cau true nano dugc xac djnh ti> ket qud hoi qui cdc s6 li?u thirc nghi?m tren phan mem tinh toan Table Curve. Ket qud xu 1^
dugc chi ra 6 hinh 2.
Hap phy As(V) tren v§t li$u Ce02-Mn203 cau tnic nano dugc m6 ta khd tot bdng mo hinh ddng nhi?t hap phy Langmuir vdi h? so hoi qui tuong irng 99,88%. Theo ket qud hoi qui cdc so li^u th^rc nghi?m tren phdn mem Table Curve dung lugng hap
TSng hgp oxit hon CeOrMnzOj...
phy cyc d^ii d6i vdi As(V) Id 57,10 mg/g, 3.3. H^p phv N H / trSn \%t lifu Ce02-Mn203 c^u true nano
0,05 g mlu dugc dua vdo binh tam gidc 250 ml chira 100 ml dung djch amoni cd nSng d$ xdc djnh, khudy trong 90 phiit (thdi gian d^t can bdng hap phy), sau dd xdc djnh nong dp amoni cdn I^i trong dung djch. Ket qud phan tich dugc dua ra d bang 3.
Hinh 2: Dudng dang nhiet hap phy As(V) tren vat li?u Ce02-Mn203 Bdng 3: Dung lugng hap phy N H / tren Ce02-Mn203 Ndng dp NHj^
ban dau, mg/l 1,00 8,70 43,50 87,00
N6ng dp NH4*
con lai, mg/l 0,12 2,05 12,87 31,94
Dung lupng hap phy, mg/g
1,76 13,30 61,26 110,12
Nong dp NH4*
ban dau, mg/l 135,02 174,05 252,50
N d n g d p N H / con lai, mg/l
61,76 99,92 175,20
Dung lupng hap phu, mg/g
146,48 148,16 154,60
Ket qua hoi qui cac s6 lieu thuc nghiem tren phdn mem tinh toan Table Curve dugc chi ra d hinh 3.
Theo ket qua hoi qui cac s6 lieu th^rc nghiem tren phdn mim Table Curve, dung lugng hdp phy CITC dai ddi vdi NH4'' la 154,54 (mg/g).
3.4. Hap phu Fe(HI) tren Ce02-Mn203 cau triic nano
Cac thi nehiem duac tien hanh tuang ty nhu doi
vdi asen. Ket qud dugc dua ra tren hinh 4.
Dung lugng hdp phu cue d^i doi vdi Fe(III) la 72,40 mg/g.
3.5. Hap phu Mn(n) tren CeOi-Mn203 cau triic
Cdc thi nghidm dugc ti6n hanh tuong tu nhu ddi vdi asen, thdi gian dat can bdng hdp phy la 60 phut.
Ket qua dugc dua ra tren hinh 5.
TCHH, T. 50(3), 2012 Lim Minh Bifi vd cgng sif Duong hap phu dano nhlst Lanngmulr NH4 cua vat llsu Co-Mn3S0
f*2-0 9BB37B22 OF A<JJ 1*2-0 B987BM3 Flt8tdEfr"3,224a»7l Fitol"1231 2004 Qmax-1G4B3S0S
e.0.03B64S7M
Hinh 3. Ducmg ding nhift hap phy amoni tren vit li?u Ce02-MnjOj
Duong dang nhiet hap phu Lanngmulr Fe cua vat lieu Cc-Mn 3 Ranks Eqn8137 FomiScql Ua.b.c.d)
r^2=099741769 DF Adj r^2=0.99397«2 FiiSidEiT=2-0368394 F s t a t = M M « i | Qmax=72.966837
Hinh 4: Dupng dang nhiet hap phy Fe(lll) tren vit lieu Ce02-Mn203
4. KET LUAN tao gel 80°C, pH = 4, ty le kim loai/PVA = 1/3, nung o 350°C trong 2 gicr.
Da tdng hpp oxit hdn hpp CeOi-MnjOj cau true Dung lupng hap phy cue dai cua oxit h6n hpp nano vcri di?n tich be mat rieng 65,31 mVg bing Ce-Mn co cau true nano doi voi As(V) la 57,10 phuang phap dot chiy gel PVA p dieu kifn: nhiet dp mg/g; amoni li 154,54 mg/g; dai vol Fe(III) la 72,97
mg/g vi Mn(ll) 60,27 mg/g.
276
TCHH, T. 50(3), 2012 Tdng hgp oxU hdn Ce02-Mn20s..
Duong dang nhiet hap phu Lanngmulr Mn cua vat Heu Ce-Mn 350 Rank20 Eqn8l36 FormSeqllJa.b.c)
[^2^.99226327 DP Adj r^2=0.9S646O72 PilSldEn=2.614TSM P)Uli:320.63393 QTnu-60.26T433
Hinh 5: Dudng ddng nhi?t hap phy Mn(Il) tren vdt li?u Ce02-Mn203 Dung lugng hap phy cyc d^ii doi vdi Mn(ll) Id 60,20 mg/g TAI L1$U THAM KHAO
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Lien he: Luu Minh Dai Vien Khoa hgc Vat lieu,
Vien Khoa hgc va Cong ngh? Viet Nam 18 Hoang Quoc Viet, Cau Gidy Ha Ngi.