Hoi nghi Khoa hoc ky' niem 35 ndm Vien Khoa hoc vd Cong nghe Viet Nam - Hd Noi 10/2010
TONG HOfP OXIT HON HOP KICH THlTOC NANOMET HE LA(Ce)- Mn VA DANH GIA KHA NANG HAP PHU CUA CHUNG DOI V 6 l
AIMONI, ASEN, SAT, IMANGAN
'LUU Minh Dai, 'Dao Ngoc Nhiem, 'Pham Ngoc Chuc,^Duong Thi Lim
'Vien Khoa hoc Vat lieu, ^ Vien Dia ly 18 - hoang Quoc Viet, Cau Giay, Ha Noi
Email: dnnhiem05(g)vaboo.com Tom tat:
Hdp phu la mdt ky thuat thich hap de xie ly amoni, asen, sdt, mangan [1-5]. Vat lieu nano chica cdc nguyen td ddt hiem chua duoc nghien cim nhieu. Vdt lieu d xit hdn hap kich thudc nanomet LaMnOs, Ce02-Mn203 duac tdng hgp a nhid do thdp bdng qud trinh ddt chdy gel ciia polyvinyl ancol vdi muoi nitrat kim logi.
Tinh chdt dgc trung cita LaMnOs, Ce02-Mn203 duac xdc dinh bdng phuang phdp nhieu xg tia X, phuang phdp hien vi dien tie qud vd phuang phdp hdp phu vdt ly LaMnOs dan pha cd kich thudc hgt trung binh < 50nm vdi dien tich be mat rieng 27,6 m^/g duac nung a 600"C trong 2 gid vd d xit hdn hap Ce02-Mn20s vdi dien tich be mat rieng 65,3 m^/g duac nung a 350 C trong 2 gid.
Dd tien hdnh ddnh gid khd ndng hdp phu cita LaMnOs, Ce02-Mn203 kich thudc nanomet ddi vdi amoni, asen, sdt, mangan trong dung dich nude. Ddnh gid khd ndng hdp phu cua LaMnOs, Ce02-Mn20s kich thudc nanomet ddi vdi amoni, asen, sdt, mangan theo md hinh ddng nhid hdp phu Langmuir. Dung luang hdp phu cue dgi cua LaMnOs kich thudc nanomet Id 52.48 mg As (III) /g; 56.08 mg As(V) /g;
104,88 mg Fe (III) /g; 98.09 mg Mn(II) /g; 87.5Img NH//g vd dung luang hdp phu cue dgi cua Ce02-Mn203 kich thudc nanomet la 7,09 mg As(V)/g; 154,54 mg
NH//g; 72,45 mg Fe(III)/g; 60.27Mn(II)/g Abstract:
LaMnOs, mixed oxide Ce02-Mn20s have been synthesised at low temperature by the combustion of gel prepared from polyvinyl alcohol (PVA), La(NOs)s, Ce(N03)4 and Mn(N0s)s- LaMnOs, Ce02-Mn20s characterizations were examined by X-ray diffraction (XRD), scanning electron microscopy (SEM) and BET (Brunaure-Emmet- Teller) measurements. The single phase LaMnOs with average primary size < 50 nm, specific surface area 27.6 m^/g was obtained at 600"C in 2h and Ce02-Mn203 with large specific surface area 65,3 m^/g was obtained at 35(fC in 2h.
The nanosized LaMnOs <^nd Ce02-Mn20s have been investigated for removing iron, manganese, arsenic and ammoniac from water. The sorption characteristic of nanosized LaMnOs and Ce02-Mn203 for AS(III), AS(V), Fe(III), Mn(II), NHf is according to the langmuir isotherm. The sorption capacities of nanosized LaMnOs are 52.48 mg/g for As (III); 56.08 mg/g for As(V); 104,88 mg/g for Fe (III);
98.09 mg/g for Mn(II); 87.51 mg/g for NH/and the sorption capacities of nanosized Ce02-Mn20s are 57,09 mg As(V)/g; 72,45 mg Fe(III)/g; 60,27Mn(II)/g;
154,54 mgNHf/g
Tieu ban: Moi tru&ng vd Ndng luang ISBN: 978-604-913-013-7
L THI/C NGHIEM LI Hoa chat, dung cu
Dung dich La(N03)3, Ce(N03)4, Mn(N03)2, As(III), As(V), NH4OH, HNO3, H2O2, Polyvinyl ancol (PVA), Na2As05, AS2O3, Fe(N03)3 dung dich NaOH dIu co do sach phan tich.
C6c chiu nhiet 100ml, 200ml, binh dinh mirc 25ml, 100ml, 250ml, 500ml, 1000ml, pipet, may khuay tir, may do hap thu quang, chen nung, tu say, 16 nung.
L2 Phuong phap nghien cuu
De danh gia mot so dac tnmg ciia vat lieu da sir dung mot so thiet bi hien dai: May Siemens D-5000(CHLB Diic) vai burc xa CuKa buac song X.=l,5406 A*'; kinh hien vi dien tir quet (SEM) JEOL - 5300 (Nhat Ban); may SA cua hang CUOLTER (My); may so mau quang hgc (Anh).
Nong do Mn, Fe, NH4"^ dugc xac dinh bang phuang phap so mau a cac buac song khac nhau: Mn voi persulfate a buoc song A,=525nm; Fe bang phuang phap phenanthroline a buoc song }^=510nm; NH4'^ bang phuong phap phenol a buoc song ^=640nm. Ham lugng asen trong cac mau thi nghiem dugc xac dinh tren may quang pho hap thu nguyen tir (AAS) cua hang Shimadzu (Nhat Ban) de xac dinh.
Danh gia kha nang hap phu ciia vat lieu theo mo hinh dang nhiet hap phu Langmuir.
2. KET QUA VA THAO LUAN 2.1 Tong hop vat lieu perovskit LaMnOa, Ce02-Mn203
Tong hgp vat lieu oxit hon hgp perovskit kich thuoc nanomet bang phuang phap dot chay gel PVA theo quy trinh nhu sau: Dung dich muoi nitrat dat hiem, Mn(N03)2 duoc tao gel voi PVA tan trong nuoc a 80°C vai pH =4 theo ty le moi kim loai/PVA =1:3. Dung dich dugc khuay trgn va gia nhiet lien tiac cho toi khi mot gel trong dong nhat dugc hinh thanh. Gel dugc lam gia trong tu say o 120°C, sau do dugc nung a 600°C trong 2 gia doi vai vat lieu LaMn03 va 350°C doi vai vat lieu Ce02-Mn203. Gian do nhilu xa tia X va anh SEM dugc dua ra a hinh l(a,b),2(a,b). Dien tich be mat dugc xac dinh bang phuang phap BET co gia tri 27.6m^/g doi vai vat lieu LaMn03 va 65,3m'^/g doi vai vat lieu Ce02-Mn203.
Vat lieu LaMn03 thu dugc don pha, co kich thuoc dong nhat < 30nm.
ul-
4.^__—i_ii. KL _. JJHoi nghi Khoa hoc ky niem 35 ndm Vien Khoa hoc vd Cong nghe Viet Nam - Hd Noi 10/2010
Hinh 1 (a): Gian dl nhieu xa tia X ' Hinh 1 (b): Hinh SEM cua LaMn03 Vat lieu Ce02- Mn203 thu dugc co cau tnic nano voi nhieu khoang trong dong nhat.
2.2 Nghien cuu kha nang sir dung LaMnOj kich thudc nanomet de hap phu sat, mangan, asen va amoni
Thoi gian dat can bang hap phu cua vat lieu LaMn03 doi vol Fe, Mn dugc xac dinh la 60 phut cua As la 150 phiit va ciia amoni la 120 phiit. De danh gia kha nang hap phu cua vat lieu chiing toi sir dung mo binh dang nhiet Langmuir [6].
2.2.1 H&p phu As a) Hdp phu As^^
Ket qua nghien cuu hap phu As(V) tren vat lieu LaMn03 dugc dua ra trong bang 1 v"
dugc the hien tren duang cong hap phu tren hinh 3:
Bdng I: Dung luang hdp phu As(V) ciia vdt lieu LaMnOs Ndng do ddu C, (mg/l)
1.05 10.00 25.05 50.15 100.05 1500.15
200.00
Ndng do eudi Cf(mg/l) 0.01
5.75 15.25 32.15 74.45 122.55 172.45
Dung luang hdp phu q (mg/g) 1.98
8.50 19.65 35.89 51.1 54.98 55.10
Tieu ban: Moi tru&ng vd Ndng lugng ISBN: 978-604-913-013-7
ng
= •
pph
1
^
Q 60-
50-
20-
10
D u o n g d ^ o g n h i e t h a p p b u l a n g m u i r q = Q m a x . b . C f / ( U b . C n
r"2=0.99874538 DF .\djr'2=0.99749il77 KilSldfc:rr=0.9JI595792 Fslal=1592.1l21 Qmax = 56.08
b = 0.031
SO IIW I'W N 6 n g d p A s ( V ) con lai C r { r a g / ' l )
- 5 0
-« s s- -.w g-
a
.. 1-
c - 10
_i)
Hinh 3: Duong ddng nhid hdp phu As(V) cua vdt lieu LaMnOs Dung lugng hap phu cue dai doi vai As ^ la Qmax=56.08mg/g.
b) Hdp phu As ^
Tuong tu nhu nghien cuu hap phu As (V), cac ket qua hap phia As (III) cho thay gia tri dung lugng hap phu cue dai doi vol As^^ la Qmax =52.48mg/g.
2.2.2 Hdp phu NH/: Da tien hanh hap phu amoni tren LaMnOs^ ket qua dung lugng hap phu cue dai doi voi NH4"^ la: Qmax=87.51mg/g.
r ? 1 r r r r
2.2.3 Hdp phu Fe : Ket qua nghien cuu hap phu Fe(III) cho thay, dung lugng hap phu cue dai doi vai Fe ^ la 104,88mg/g.
r -J I ' r r r
2.2.4 Hdp phu Mn : Ket qua nghien cuu hap phu Fe(III) cho thay, dung lugng hap phu cue dai doi vai Fe ^ la 98,09 mg/g.
2.3 Nghien cuu kha nang sir dung Ce02-Mn203 kich thuoc nanomet de hap phu sat, mangan, asen va amoni
2.3.1 Bdnh gid kha ndng hdp phu As(V) cua vat lieu Ce02 - Mn203
Thi nghiem dugc tien hanh nhu sau: 100ml dung dich nong do tir lmg/1 din 200 mg/1 pha tir dung dich As(V) chuan dugc khuay lien tuc voi 0.05g mau tren may khudy tir. Sau 120 phiit lay mau ra xac dinh nong do As con lai. Ket qua dugc dua ra trong hinh 4.
Hoi nghj Khoa hoc ky' niem 35 ndm Vien Khoa hoc vd Cong nghe Viet Nam - Hd Not 10/2010
Dung lugng hap phia cue dai Qmax = 57.09 (mg/g)
2.3.2 Hap phu NH/ cua vat lieu Ce02-Mn20s kich thu&c nanomet theo mo hinh ddng nhiet hap phu Lanngmuir
Thi nghiem dugc tien hanh nhu sau: 100ml dung dich nIng do tir lmg/1 din 200 mg/1 pha tir dung dich NH4'' 1000 nig/1 dugc khuay lien tuc vai 0.05g mlu tren may khuay tir. Sau 90 phut lay mau ra xac djnh nIng do NH4"^ con lai va kit qua thi hien a hinh 5.
b
1 7 5 -
1 5 0 -
125-
100-
7 5 -
5 0 -
2 5 -
0
Duong hap phu dang nhiet Lanngmuir NH4 cua vat lieu Ce-l\/ln350
r"2=0.99837822 DF Adj r«2=0.99675643 FitStdErT=3.2242971 Fslat=1231.2094 Q m a x =154.53565
c=0.039845756
• „ . — •
3 50 100 150
Of
175
150
•125
•100
a
•75
•SO
2 5 n 200
LTinh 5: Dudng ddng nhid hdp phu amoni tren vdt lieu Ce02-Mn20s Dung lugng hap phu cue dai Qmax = 154.5 (mg/g).
2.3.3 Hdp phu Fe : Ket qua nghien cuu hap phu Fe(III) cho thay dung lugng hap phu cue j+
dai doi voi Fe *' la 72,4mg/g.
2.3.4 Hdp phu Mn^^: Ket qua nghien cuu hap phu Fe(III) cho thay dung lugng hap phu cue dai doi voi Fe ^ la 60,2 mg/g.
3. KET LUAN
Da tong hgp oxit hon hgp be dat hiem mangan co kich thuac nanomet (<50nm), voi dien tich bl mat rieng Ion (27,60m^/g doi voi LaMn03, 65,31m^/g doi voi Ce02-Mn203) bang phuang phap dot chay gel PVA a dieu kien: Nhiet do tao gel 80*^0, pH = 4, ty le kim loai/PVA = 1/3, nung o 350*^0 (dli vol Ce02-Mn203), 600"C (doi voi LaMn03) trong 2 gia.
Da nghien cuu ung dung vat lieu LaMn03 kich thuoc nanomet va vat lieu oxit hon hgp Ce-Mn CO cdu triic nano de hap phu As(III), As(V), Fe(III), Mn(II) va NH4^ xac dinh dugc:
- Dung lugng hap phu cue dai cua vat lieu LaMn03 kich thuac nanomet tuan thii theo mo hinh hdp phu ddng nhiet Langmuir doi vol As(III); As(V); Fe(III); Mn(II); NH4'^
ldn lugt la 52,48; 56,08; 104,88; 98,09; 87,51mg/g.
- Dung lugng hap phu cue dai cua oxit bon hgp Ce-Mn co cau triic nano doi vol As(V);
Fe(III); Mn(II); amoni, ldn lugt la 57,09; 72,40; 60,20; 154,5mg/g.
Tiiu ban: Moi tru&ng vd Ndng lugng ISBN: 978-604-913-013-7
LOfI CAM ON
Tap thi tac gia chan thanh cam on Ban tl chiic Hgi nghi Khoa hgc 35 nam Vien Khoa hgc va Cong nghe Viet Nam da cong bl bao cao trong tuyIn tap bao cao cua Hgi nghi.
TAX LIEU THAM KHAO
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2. Pham Van Lam, Phan Thi Nggc Bich, Dao QuIc Huong, "Chi tgo, khdo sdt cdc ddc trung vd hieu icng hdp phu asen ciia vdt lieu oxit sdt tir kich thudc nano "; Tap chi Hoa hgc, T45, s6 2 - 2007, Tr. 11 - 15.
3. Le Ba Thuan va cong sir, "Removov arsenic from water using rare earth based materials", Journal of Chemitry, vol- 46(2A)- 2008,, pp 459-462.
4. Chang Y.Y., Kim K.S., Jung J.H., Yang J.K., Lee S.M., "Application of iron - coated sand and manganese - coated sand on the treatment of both As(III) and As(V) ", Water Science & Technology, Vol 55 No 1 - 2 (2007), PP 6 9 - 7 5 .
5. Dinesh Mohan, Charles U. Pittman Jr., "Arsenic removal from water/ wastewater using adsorbents", A critical review. Department of Chemistry, Mississippi State University, Mississippi State, MS 39762, USA, (2007).
