Tieu ban: Moi tru&ng vd Ndng lugng ISBN: 978-604-913-013-7<br />
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CHE TAO vA iTNG DUNG NANO TiOj DE XLT LY CAC CHAT DOC<br />
HAI TRONG MOI TRUOfNG KHONG KHI 6 VIET NAM<br />
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Nguyin Thi Hue'. Tran Thi Duc^, Ma Thi Anh Thu^, Dinh thi Thiiy HSng'*<br />
'Vien C6ng nghe M6i truong; ^Vien Vat ly Lfng dimg va Thiit bi khoa hgc;<br />
Truong Cao dang Su pham Cao Bing; "^Truong Dai hgc Hang hai Hai Phong<br />
Email: nthue2003(^yahoo.com<br />
Tom tat:<br />
Lap phii Anatase Ti02/ AI2O3 dutyc chi tgo thdnh cdng khi sie dung hdn hop<br />
dung dich TTIP, AC AC, nude khie ion vd cdn. Lap phii TiOi/SiOs duac chi tgo cd hieu<br />
qua khi diing TBOT, cdn,^ nude khir ion vd DEA. Anatase Ti02 cd cdu true tinh thi tdt<br />
xudt hien a 550°C ddi vdi cd hai chdt mang. Tinh thi TiO: mgnh han khi diing<br />
dung dich sol B. Khi sie dung phuong phdp sol-gel, chiiu ddy lap Ti02 trin di<br />
bdng thgch anh khodng 0,4 um vd soi oxit nhdm Id 200nm trong khi su dimg<br />
phuang phdp phun phii^ Ti02 dgng huyen phii thu duac chiiu ddy la 3 um. Kit qud<br />
phdn tich trin SEM thdy rd su dong diu ciia lop anatase tren sai AI2O3 vd sir tdng<br />
chiiu ddy ciia lap Ti02 khi thay ddi thdnh phdn sol trong dung dich.<br />
Ti02/Al203 vd Ti02/Si02 cd cdu triic dgng nano xdp duac xem nhu vd gidi phdp tot doi vdi<br />
xie ly d nhiem khdng khi (dgc bid v&i cdc khi NO vd CO) phdt sinh tic cdc hogt ddng giao<br />
thdng Khi chiiu sdng bdng den UV/(nO/Al202;Ti02/Si02), cdc khi CO vd NO cd nong do 5<br />
ppm sau vdi gid biphdn hiiy hodn todn.<br />
Abstract:<br />
Anatase Ti02/Al203 layer has been successfully fabricated when using a mixed solution of<br />
TTIP, ACAC, demonized water and ethanol Ti02/Si02 layer fabrication effective when<br />
TBOT, ethanol demonized water and DEA are applied. Anatase Ti02 a fine crystalline<br />
structure found at 55(fC for both substrates. Ti02 crystal much finer when using sol B<br />
solution. When using the sol-gel method, the thickness ofTi02 layer is about 0.4 umfor quartz<br />
fibers and 200 nm for AW3 fiber while it is about 3 um f method of TiOi suspension by spray<br />
is applied. SEM results revealed the uniformity ofAnatase layer on AI2O3fibersand increase<br />
in the thickness ofTi02 layer by change ofsols composition.<br />
TiO/Al203 and Ti02/Si02 - soft nano structures, can be regarded as good solutions for the<br />
treatment of air pollution (particularly by NO and CO) resulted from traffic activities.<br />
Illuminated by UV/(Ti02/ AI2O3; Ti02/Si02), CO and NO of 5 ppm concentration are<br />
completely decomposed after several hours.<br />
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1. Md DAU<br />
Quang xuc tac tiari dioxit (Ti02) hien dang dugc tap trung nghien cuu nhu mgt trong<br />
nhirng c6ng nghe co trien vgng nhit dl giam thilu cac chit 6 nhiem trong m6i truang [1-3]. Ti02<br />
voi kich thuoc tirih thi nho co vai chuc nanomet, bin, co hieu ung xuc tac cao nen co kha<br />
nang xu ly cac chat 6 nhiem trong kh6ng khi tit va re ban so vai phuang phap hip phu khac.<br />
Ti02 CO kha nang phan hiiy hoan toan cac chit dgc hai din san p h i m v6 hai, chi phi'diu tir<br />
va van hanh thap, qua trinh oxy hoa dugc thuc hien trong dilu kien nhiet do va ap suit<br />
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Hgi nghi Khoa hgc ky niem 35 ndm Vien Khoa hgc vd Cong nghe Viet Nam - Hd Not 10/2010<br />
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binh thuang. Nguai ta khang dinh Ti02 la vat lieu quan trgng trong c6ng nghe lam sach<br />
kh6ng khi va nuoc nha vao nang lugng anb sang mat trai.<br />
Mang Ti02 phu len gach men, cac thiet bi ve sinh, kinh cua so co kha nang tu lam sach va<br />
diet khuan. Ti02 nano dugc cho la vat lieu quan trong trong c6ng nghe lam sach khong khi nha<br />
vao nang lugng anh sang mat trod. Viec su dung cac chat mang de tang kha nang xuc tac cho<br />
Ti02 la van de can thiet. Cac vat lieu nhu bong thach anh (Si02), sgi 6xit nhom kim loai (AI2O3)<br />
la nhirng vat lieu co dien tich be mat tiep xiic Ion, dac biet sgi AI2O3 co cau tnic tinh the, do ben<br />
CO hgc cao, kh6ng bi thay d6i trong qua trinh nhiet boa diing lam vat lieu phu Ti02 co trien<br />
vgng cao trong xu ly khi thai phat tan trong m6i truang [4-7]. Nhiing nghien ciiu mai nham<br />
hoan thien c6ng nghe va tao ra nhiing vat lieu da chuc nang mai voi boat tinh xiic tac manh, co<br />
do bam dinh t6t de xu li 6 nhiem moi truang kh6ng khi la ly do cua bai bao can nghien cim. Vi<br />
vay, muc tieu ciia bai bao nham tao lop phu Ti02 co cau tnic tinh the cao tren cac de mang khac<br />
nhau trong be th6ng mang loc cua thiet bi lam sach kh6ng khi, xir li miii hoi, cac chat doc<br />
hai,.. .trong m6i truong.<br />
Phuong phap sol- gel la mgt phuang phap t6ng hgp vat lieu hien dai, di tu vat lieu<br />
ban dau la cac alkoxide, nhung san pham cuoi ciing thu dugc thuong c6 chat lugng rat<br />
cao, do tu mgt tien chat (precusor) co the thuc hien d6ng thai hai qua trinh phan li (thuy<br />
phan) va ket tu (ngung tu) tao mach va luoi hoa. Do do sol - gel la mgt phuang phap to<br />
ra rat uu viet de t6ng hgp nhftng vat lieu co kich co nano hay nhftng mang sieu mong.<br />
Dieu che h6n hgp sol-gel vai ti le khac nhau ve thanh phan boa hgc de tao dugc lop phu<br />
Ti02 CO do bam dinh, dong deu tren be mat AI2O3 va Si02 x6p, nho min va co kha nang quang<br />
boa cao la van de can thiet phai nghien ciiu [8,9]. Cac dieu kien t6i uu trong qua trinh tao<br />
mang Ti02, thanh phan boa hgc cua dung dich nhiing phu da dugc kiem tra qua phuong phap<br />
nhilu xa tia X (XRD), quet vi dien tu va pb6 truyen qua (SEM).<br />
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2.THirC NGHIEM<br />
2.1. Hoa chat va thiet hi<br />
Hod chdt<br />
Cac dung dich titanium tetraizopropoxide Ci2H2804Ti (TTIP); tetrabutylortbotitanate<br />
Ti(OC4H9)4 (TBOT); ethanol CeHjOH (EtOH); acetbylacetone C5H8O2 (ACAC) va<br />
diethanolamine C4H11NO2 (DEA) diing dl dieu che dung dich sol-gel dugc mua tu hang<br />
Wako, Nhat ban. AI2O3 co duong kinh 0,1mm va dien tich be mat la 0.015 m^/g dugc mua tu<br />
hang Alus, Nhat Ban.<br />
Thiet bi<br />
Qua trinh xu ly nhiet dugc tiln hanh trong 16 co chuong trinh dieu khien nhiet do tu dong<br />
cua hangYamato, Nhat Ban. Ciu tnic tinh thi cua cac lop mang dugc xac dinh bang phuong<br />
phap nhieu xa tia X (Siemens D-5000). Hinh thai be mat va chieu day lop mang dugc quan<br />
sat boi qua trinh quet vi dien tu truyin qua SEM (Hitachi S-4800).<br />
2.2. Phuong phap thi nghiem<br />
Cbl tao vat lieu nano Ti02 bao gom 3 phin chinh: qua trinh pha che dung dich sol Ti02,<br />
nhiing phii vat lieu va qua trinh ii nhiet. Dung dich sol Ti02 dugc dieu che dua vao qua trinh<br />
thuy phan va ngung tu cua cac alkoxh titan. Mang mong Ti02 nano x6p dugc tao ra bang<br />
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Tiiu ban: Moi tru&ng vd Ndng lugng ISBN: 978-604-913-013<br />
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each lang dgng sol Ti02 len de mang. Qua trinh thuy phan va ngung tu tao mang Ti02 co the<br />
dugc m6 ta trong so d6 sau:<br />
t°<br />
Ti(0R)4 + H2O ^ HO - Ti(0R)3 + ROH<br />
Ti(0R)3(0H) + H2O t" ^ (H0)2 - Ti(0R)2 + ROH<br />
Ti(OR)2(OH)2 + H2O t"^ (H0)3 - Ti(OR) + ROH<br />
Ti(0R)(0H)3 +H2O .0 Ti(0H)4 + ROH<br />
'^-K<br />
Ca hai phan ling thuy phan va ngung tu deu tham gia vao sir bien d6i alkoxide thanh khung<br />
oxit, do do cau tnic hinh thai hgc cua cac oxit thu dugc phu thuoc rat nhieu vao kha nang<br />
phan ung cua hai phan ling nay. Ethanol dugc su dung trong nghien eftu nhu mgt dung m6i dl<br />
boa tan TTIP va TBOT [10].<br />
Dung dich sol dugc lang dgng len de mang la sgi AI2O3 hoac b6ng thach anh bang phuang<br />
phap nhiing phu hay phun de tao mang m6ng. Sgi AI2O3 hoac b6ng thach anh sau khi da tim<br />
phu sol Ti02 len tren be mat dugc de kh6 tu nhien 6 nhiet do phong. Tien hanh u nhiet 6 cac<br />
khoang thai gian khac nhau. Khi thieu kit duoi 400°C ton tai mgt phin Ti02 a dang v6 djnh<br />
hinh nhung tren 700°C se tao ra tinh thi Ti02 dang rutile co boat tinh thip. Mang dugc danh<br />
gia la t6t neu sau qua trinh u nhiet cau tnic tinh the cua mang chi co duy nhit anatase Ti02 vi<br />
thanh phan nay cho boat tinh quang xiic tac cao. Chilu day cua mang tang din theo sl lin<br />
nhiing-phu-u nhiet.<br />
Ngoai ra, co the tao mang Ti02 nano tu bgt Ti02 thuong mai P25-Degussa (Diic), bot<br />
Ti02- P25 CO kich thuac hat ca 25 nm va bl mat rieng la 55 mVg. Su dung phucmg phap nay<br />
CO the n h p dugc cac lop Ti02 c6 do day Ion hon. D I tao dugc lop phii Ti02 nano bam dinh<br />
t6t tren de mang ta co thi dua vao sol Ti02 mot lugng bgt nano Ti02 - P25 thich hgp. D I tach<br />
cac cum hat P25 thanh cac hat Ti02 rieng le, bin hgp sol Ti02 voi P25 dugc khuiy manh 6<br />
nhiet do phong, sau do rung sieu am cho din khi P25 phan tan diu thanh dung dich Ti02<br />
huyen phu mau trang sfta.<br />
3. KET QUA v A BIEN LUAN<br />
3.1. Dieu che cac dung dich sol-gel<br />
3.I.L Sol-gel diing cho vat lieu oxit nhom kim loai<br />
Hon hgp dung dich TTIP: ACAC: nuac cit: EtOH voi cac ti le moi khac nhau co thanh<br />
phin tuong duong la 2:1: 3: 20 va 2: 2: 3: 20 (tuong ung voi ky hieu la sol 1A va sol IB). D I<br />
tao dung dich a the ding nhat, sau khi pha cbl, cin khuiy trong khoang 5 gio. Dung dich culi<br />
ciing thu dugc kh6ng mau trong su6t va ding nhit.<br />
3.L2. Sol-gel diing cho vat lieu bong thach anh<br />
TBOT va DEA dugc boa tan trong EtOH, khuiy kT trong 3 gia a nhiet do phong. Them nuoc<br />
va EtOH tu tii vao dung dich nay va khuiy nhe. Thanh phin boa hgc ban diu cua sol dugc sir<br />
dungtiieoty le moi tuong ung: Ti(OC4H9)4: C2H5OH: H2O: NH(C2H40H)2 = 1:38:1:1.<br />
3.2. Qua trinh tao mang tren bong thach anh va soi oxit nhom<br />
Tgo mdng trin bdng thgch anh: Dli vai dl mang la b6ng thach anh, co 2 dung dich sol tim<br />
phu tren vat lieu nay. Cac dung dich sol nay dugc ling dgng len dl b6ng thach anh bing<br />
phuong phap phun tao mang m6ng. Sau do b6ng thach anh da tim phii sol Ti02 dugc dl kh6 a<br />
nhiet do phong khoang 7-8 gia roi thieu ket trong m6i truong kh6ng khi a 550°C trong 1 gia.<br />
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Tgo mdng trin spi oxit nhdm: Cac sgi AI2O3 dugc vo tron thanh timg biii nho dugc nhung<br />
vao dung dich da pha che. Cau true tinh the ciia mang khong chi phu thuoc vao qua trinh u<br />
nhiet va con phu thuoc vao thai gian nhung phu. Khao sat qua trinh nhiing trong khoang thoi<br />
gian 10, 20, 30, 60, 90 va 120 phiit. Ket qua nghien ciiu cho thiy, mang Ti02 phu tren cac sgi<br />
AI2O3 CO cau tnic tinh the anatase cao la nhirng mang dugc nhiing trong dung dich sol-gel<br />
trong thai gian 60 phiit [11]. Lop gel Ti02 dugc hinh thanh tren AI2O3 nha qua trinh lam kh6<br />
tu nhien 6 nhiet do phong trong thai gian khoang 1 ngay. Qua trinh xu ly nhiet dli vod mlu<br />
trong cac khoang nhiet do khac nhau tu 450, 500, 550 va 600°C da dugc khao sat. Cac gia tri<br />
nhiet do nay dugc gift trong cac khoang thoi gian ii khac nhau tu 1, 2, 3, 4,....10 h [12]. Qua<br />
khao sat, tai nhiet do cue dai 500°C gift trong 3 gia, the anatase deu c6 cau tnic tinh the chit<br />
lugng cao d6i voi ca hai loai dung dich sol-gel.<br />
3.3. Dac tinh cua mang TiOi qua Idem tra bang phuong phap XRD va SEM<br />
Phan tich tren XRD<br />
Ket qua phan tich tren XRD (hinhl) cho thay, be mat sgi AI2O3 co hinh dang g6 ghe nhu<br />
lap vay ca, do vay tao lop phu d6ng deu rat kh6 mac du dien tich tiep xuc Ion. Cac nghien cuu<br />
da chi ra, voi thai gian nhung trong cac dung dich sol lb, a dieu kien xu ly nhiet t6t nhat nhu<br />
da neu tren, lop anatase dugc hinh thanh rieng biet tren sgi AI2O3 co cau true tinh the dang<br />
cao (hinh 2) cua mau B t6t hon mau A. Ci vi tri goc 2theta = 25.27°, tuong ling voi A (101).<br />
Cac peak khac o vi 33.90° va 48.09° tuong duong voi A (004) and A (200)[13]. Gia tri do<br />
2.41 A° va 2.12A° la vi tri cua peak Al (200c) and Al (202c) [14]. Do ban chilu rgng cua cac<br />
peak thay rang, peak cua mau B c6 cuong do cao, ro net nhung rgng ban peak cua mau A.<br />
dieu do chung to rang tinh the Ti02 trong mau B co kich thuoc nho ban trong mau A. Nhu<br />
vay, mau B co boat tinh xiic tac t6t hon.<br />
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H.l: Sgi AI2O3 tru&c khi lam phu Ti02 H.2: Pho XRD ciia hai sol A (1) vd sol B (2)<br />
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Phdn tich tren SEM<br />
Do day mang dugc xac dinh bang phuong phap anpha hoac tinh tu kh6i lugng rieng, dien<br />
tich va trgng lugng. M6i lan phu, khi dung phuang phap sol - gel nhan dugc do day cua lap<br />
Ti02 tren b6ng thach anh co 0,4 um va ca 3 um vai mang tu bgt Ti02 - P25 va co 200 nm d6i<br />
voi vat lieu AI2O3. Chieu day lop mang tang len cung vai s6 lan lap lai cua qua trinh tao<br />
nhung - phu va xu ly nhiet. Chieu day ciia lop Ti02 trong mau A tang tu 140 nm den 200 nm<br />
trong mau B. Dieu nay lien quan den van de khi tang lugng ACAC trong dung dich sol-gel,<br />
chieu day lop anatase dugc tang len ro ret. Do co nhom C = O trong cau tnic phan tu nen<br />
ACAC CO kha nang tao phuc manh vai cac nguyen t6 khac, dac biet la kim loai chuyen tiep de<br />
tao ra hon hgp dan xuat alkoxide. Nhftng dan xuat nay rat ben, vi the alkoxide kim loai kh6ng<br />
bi thuy phan hoan toan tao ra hydroxide kim loai ket tiia anh buong den chat lugng (do dong<br />
deu, kich thuoc hat, do truyen qua) cua vat lieu che tao dugc. Mat khac khi tang lugng ACAC<br />
trong thanh phan s6 moi phan tu, se lam kha nang chuyen hoa Ti02 dang hiru co ve Ti02 v6<br />
CO trong gel nhieu hon.<br />
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223<br />
Tieu ban: Moi tru&ng vd Ndng lugng ISBN: 978-604-913-013-7<br />
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Hinh 3 a,b la ph6 SEM cua anatase Ti02 bam tren be mat AI2O3 cua mau A va B tuong<br />
img. Nhin vao ph6 ta thay tinh the Ti02 cua mau B c6 kich thuac nho ding diu so vaitinhthi<br />
Ti02 trong mau A. Hinh 4 la pho SEM cua mau b6ng thach anh dugc tim phu huyin phu Ti02.<br />
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H 3a: Pho SEM cua Anatase H.3b: Phd SEM ciia H. 4: Pho SEM cita bong H. 5: Do ddy ca 1 um ciia lap<br />
Ti02 khi sic dung sol A AnataseTi02 l£k . . . -(b)<br />
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