TAPCHIHOAHQC T.51(6) 731-735 THANG 12 NAM 2013
NGHIEN CU'U KHA NANG HAP PHU ASEN(III) VA ASEN(V) TREN ZrOz KiCH THU'aC NANOMET
D a o N g o c N h i e m " ' , T r i n T r u n g K i e n ^ D u o n g T h i L i m ^ N g u y e n T r o n g U y l n ^ Vien Khoa hoc Vdl lieu, Vien Hdn ldm Khoa hgc vd Cdng nghe Viet Nam
'Khoa Hoa hgc. Truang Dgi hgc Khoa hgc Tu nhien, DHQGHN Viin Dia Ly. Vien Hdn ldm Khoa hgc vd Cong nghe Viet Nam
Dgn T d a soan 3-6-2013
A b s t r a c t
Nanosized Zr02 has been sythesized at low temperature (600 "C) by the combustion of mixture from polyvinyl alcohol (PVA) and zirconyl nitrate. The smgle phase Zr02 has average primary size < 50 nm. The adsorbtion charactenstics of the nanosized Zr02 for arsemc(III) and arsemc(V) are according to the Langmuir Isotherm. Time to reach equilibrium adsorption of As(III) and As(V) on the nanosized Zr02 is 120 minutes. The adsorbtion capacities of nanosized Zr02 are 65.44 mg As(III)/g and 68,83 mg As(V)/g.
Keywords: Nanosized Zr02, removing arsenic(III) and arsenic(V), Langmuir Isotherm.
1. M O DAU
Quang zirconia d Viet N a m kha phd bien va cd trii lugng ldn nam trong cat sa khoang ven biSn mien trung va Quang Ninh [1]. Zirconia d d n g vai trd quan trgng trong thanh phan ciia cac bdt mau gdm va Imh kien dien tir [1-3]. Nhii'ng vat lieu chira zircon cd tac dung lam tang kha n a n g chju mai mdn va d u g c sir dung rpng rai trong cac n g a n h san xuat vat lieu chiu Ilia nhu: gach g d m , ndi nau kim loai, thiet bi lpc,...Ngoai ra, n h d kha n a n g chju luc tdt va dp ben cao cua gdm zirconia nen nd d u g c sir dung lam khudn ep, thiet bi nghien, Idp Idt g d m , d u n g cu cat, mat van, dng dan h u d n g , . . . [3].
Mat khac, Zr02 ket h g p vdi mdt sd oxit khac cdn dugc irng dung lam chat xiic tac, lam dien c u e , kinh quang hgc [ 2 - 4 ] . . . . D a c biet, gan day, ZrOi kich thudc micromet va n a n o m e t cdn d u g c nghien ciiu, ling dung lam vat lieu xii ly mdi t r u d n g bi d nhiem day trien vgng [5-9].
Trong nghien ciru nay, chiing tdi sir d u n g ZrO^
kich thudc nanomet d u g c tdng h g p bang p h u a n g phap ddt chay gel polivynyl ancol ( P V A ) d nhi?t dg thap de hap phu asen tir mdi t r u d n g n u d c . 2.THUC NGHIEM
2.1. H o a c h a t v ^ t h i e t bi
Axit nitric H N O j , H2O2, N H 4 O H , As(III) va
As(V) deu cd dp sach phan tich va Zr02 ki'ch t h u d c nano d u g c c h e tao theo tai Heu [8, 9].
2.2. Dieu kien t h i n g h i e m va p h u o n g p h a p n g h i e n Cliu
Thi nghiem h i p phu d u g c tien hanh nhu sau. 100 mt dung dich asen cd n d n g dp t u o n g iing khuay lien tuc tren may khuay tir d nhiet dp 25 "C vdi 0,05 g ZrOi kich thudc nanomet trong binh tam giac 250 ml. Ly t a m lay dung dich trong va xac dinh ndng d o asen cdn lai trong dung djch tren may AAS-6800, Shimadzu (Nhat Ban).
Danh gia kha nang hap phu asen tir dung dich theo md hinh hap phu dang nhiet Langmuir. Dung lugng hap phu c u e dai va hang sd dang nhiet d u g c xac djnh bang p h u o n g phap hdi quy. Mdi tucmg quan cac sd lieu t h u c nghiem giua ndng do asen cdn lai trong dung dich (Cf, mg/I) theo dung lugng hap phu bao h d a (q, mg/g) d u g c xii ly tren phan mkn\
tinh toan Table Curves.
D u d n g dang nhiet bap phu Langmuir d u g c ap d u n g thanh cdng vao nhieu qua trinh hap phu cac chat d nhiem va d u g c sir d u n g rgng rai nhat trong viec md ta qua trinh hap phu cac chat tan tir dung dich theo p h u a n g trinh Langmuir cd d?tng:
\-\-bxCf Trong dd:
TCHH,T 51(6), 2013
Qrmx: Dung lugng hap phu cue dai tren be mat don Idp, mg/g,
q: Dung lugng hip phu, mg/g,
b: Hing sd ding nhiet ciia phuang trinh, dm^/mg,
Cr: Ndng do asen cdn lai trong dung dich, mg/1.
3 KET QUA THAO LUAN
3.L Tdng hgp ZrOj kich thudc nanomet 0 nghien ciiu [8, 9] da tdng hop Zr02 don pha (hinh !), ciu triic dang lap phuang vdi kich thudc ddng nhat < 50 nm (hinh 2) bing phuong phap ddt chay gel trong dieu kien: pH = 1, ty le Zr'^^/PVA = 1/3, nhiet do tao SOT, nung d dOOT trong 2 gid.
Ddo Nggc Nhi?m vd cdng sir
Hinh I' Gian dd nhieu xa tia X ciia Zr02 [8, 9]
Hinh 2: Anh SEM ciia Zr02 [8, 9]
Trong nghien ciru nay, se nghien ciiu danh gia kha hap phu asen bang Zr02 kich thudc nanomet tdng hgp bing phuang phap dot chay gel polyvinyl ancol (PVA).
3.2. Nghien cihi kha nang hap phu asen tren ZrO, kich thvdc nanomet
3.2.1. Anh hudng cua thdi gian t&i hieu sudt hdp phu asen tren ZrO:
Cac thi nghiem dugc tien hanh nhu sau: 100 ml the tich dung djch asen(III) cd ndng dd 1 mg/1 khuiy lien tuc tren may khuay tir d nhiet do 25°C vdi 0,05 g ZrOi trong binh tam giac 250 ml. Ly tam lay dung dich va xac dinh ndng do asen cdn lai trong dung dich tren may AAS-6800, Shimadzu (Nhat Ban). Ket qua nghien ciiu dugc dua ra trong bang 1, hinh 3.
J /; Hieu suat hap phu asen(in) theo thdi gian tren Zr02 Nong do asen(III)
ban dau C„ mg/1 1,00 1,00 1,00 1,00 1,00 1,00 1,00
Thoi gian t, min 0 30 60 90 120 150 180
Nong do asen(III) lai C',, mg/1
1,00 0,80 0,35 0,20 0,05 0,01 0,01
Hieu suat hap phu H, %
0 20 65 80 95 99 99 Tir ket qua phan tich bang 1 va hinh 3, thay rang
thdi gian hap phu anh hudng Idn den hieu suat hap phu asen(lll) ciia Zr02 kich thudc nanomet. Qua trinh hap phu xay ra nhanh trong 90 phiit dau vdi hieu suat 80% va gan nhu dat can bang d 120 phiit.
Ddi vdl As(V), chiing tdi ciing thu dugc cac ket qua tuong tu. Vi vay, 120 phiit dugc lay la thdi gian dat can bang cho ca As(in) va As(V). Ket qua nghien ciru anh hudng cua thdi gian dat can bang hap phu den hieu suat hap phu ciia chiing tdi tuong duong vdi cac nghien cuu [5, 6].
3 2 2. Xdc dinh dung lugng hdp phu asen Trong cac thi nghiem hap phu dugc tien hanh nhir sau: Ndng do ban dau ciia asen tir 1 m^l den 200 mg/1 dugc khuiy lien tuc vdi 0,05 g Zr02 tren may khuiy tir. Khi qua trinh hap phu dat can biiig, lay mau de xac djnh ndng dp asen. Cac hang sd dang nhiet ciia qua trinh hap phu asen tren vat lieu ZiO:
dugc xac dinh tir ket qua hdi qui cac sd lieu th\rc nghiem bang phan mem tinh toan Table Curve. Cac ket qua nghien cun ve hap phu asen trudc va sau khi dat can bang hap phu dugc phan tich ghi Iai d bang 2.
TCHH, T. 51(6), 2013 Nghien ciru khd nang hap phu..
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^ 1
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c 08
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< 04 Ol 02
^ 0
--
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\ -
0 50 100 150 Thd-i gian hdp phu t (phut)
-
200
Hinh 3: Bieu dien ndng do asen(III) cdn lai theo thdi gian hip phu Bdng 2- Dung lugng hip phu ciia Zr02 ddi vdi As(ni) va As(V) Nong do asen ban diiu
C„ mg/I 1 10 25 50 100 150 200
Nong do asen eon lai Cf, mg/I D6i voi As(III)
0,05 5,55 14,45 30,35 72,15 117,95 167,85
Doi vcri As(V) 0,05 5,20 13,95 30,05 70,85 115,95 165,85
Dung lirgng hap phu asen q, mg/g D6i voi As{in)
1,90 8,90 21,10 39,30 55,70 64,10 64,30
DSi voi As(V) 1,90 9,60 22,10 39,90 58,30 68,10 68,30 Tir ket qua bang 2 tinh dugc dung lugng hap phu (Cf, mg/1) theo dung lugng hap phu bao hoa (q, bao hoa ciia ZrOj d cac ndng do asen khac nhau. Tir mg/g) xac djnh dugc dung lugng hap phu cue dai cac ket qua hoi quy mdi tuong quan cac sd lieu thuc (Qmax, rng/g) va hang sd dang nhiet. Kel qua tinh nghiem giii'a ndng do asen cdn lai trong dung dich toan thuc nghiem dugc ghi lai d hinh 4 (a,b).
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l>ji^S i ] ^ g nhipi hJp phu Langmuir q ^ Q m u h . C I X l t b C f l
hMnt d^ A I (IH) OK III a (mlJI)
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Hinh 4a: Dudng ding nhiet hap phy As(III) tren Zr02
TCHH, T. 51(6). 2013 ijao nggc ivrii^iri cu f^yi's "¥
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I>i>ang d i n g nhiCt h ^ phu L i a g m i i r q = QniJi.b.CMH*,Cn
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N6ng do As (V) cjn lai Cf < i n ^ )
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/fi«/i '#6.- Dudng dang nhiet hap phu As(V) tren ZrO:
Hinh 4(a,b) bieu dien dudng hap phu dang nhiet Langmuir ddi vdi As(IlI) va As(V) ciia ZrOi dugc tdng hgp bang phuang phap ddt chay gel d nhiet dp thap. Ket qua nghien ciiu cho thay qua trinh hap phu asen bang ZrO: dugc md ta kha tdt theo md hinh dang nhiet hap phu Langmuir vdi he sd hdi qui > 99
%. Dung lugng bap phu cue dai (Qmax) tinh theo md hinh Langmuir ciia Zr02 ddi vdi As(III) la 65,44
mg/g, As(V) ia 69,83 mg/g. Ket qua nghien ciiu nay tuang duong vdi nghien ciiu [5, 6]. Theo nghien ciiu ciia T. Balaji va cac cdng su [6], cac tac gia da che tao dugc vat lieu ZrO: mang tren nhua vdng cang axit lysin diaxetic (Zr-LDA) va ciing dua ra gia thuyet ca che hap phu asen cua vat lieu Zr-LDA theo md hinh trao ddi phdi tu nhu hinh 5 (a,b).
//Y/y
o
o
HjAsO^
O
^ N - Z r ^ H z A s O j
Hinh 5a. Co che hap phu voi As(III) eOa vat lieu Zr-LDA [6]
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^ N - Z r < r X
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| ^ ^ , ^ d l X . H ,
o
^ N - 2 r ^ - H 2 A s O : N^^l^^oi^ + X H y<y^ ^
O ^ Hinh 5b: Ca che hip phu vdi As(V) ciia vat lieu Zr-LDA [6]
Vat lieu nay cung dugc nghien ciru tai sinh bing each riia giai bing dung djch NaOH I M. Sau 6 lin hap phu, giai hap khdng thay sir xuit hien cua ion Zr''"' trong dung djch. Dieu nay chiing td Zr""^ mang tren nhua rat ben, hau nhu khdng rua trdi trong qua trinh sir dung. Day cung la ca sd dk chiing tdi dinh hudng cho cac nghien ciiu tiep theo nhu: Nghien ciru chpn chat mang phii hgp de ch6 tao vat Heu hip phu chiia ZrO: kich thudc nanomet.
4. KET LUAN
Da khao sat thdi gian dat can bing hip phu ciia ZrO: dugc tdng hgp bang phuang phap dot chay gel d nhiet do thap den hieu suat hap phu asen. Thin gian dat can bing hap phu As(III) va As(V) tren Zr02 la 120 phiit.
Da nghien ciiu, danh gia kha nang hip phy asen tren ZrO: ket qua cho thay: Dung lugng hip phu circ dai ciia vat lieu Zr02 kich thudc nanomet dugc tong
r H H , T . 51(6). 2 0 1 3
igp bang p h u a n g p h a p ddt c h a y gel d nhiet d o thap ldi vdi A s ( n i ) va A s ( V ) l i n lugt la Q^^x = 65,44 ng/g va 69,83 m g / g .
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Nghien cuu khd nang hap phu...
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Lien hi: D a o Ngoc N h i e m Vien K h o a hgc vat lieu,
Vien Han lam K h o a h p c va C d n g n g h e Viet N a m 18 H o a n g Q u d c Viet, Cau G i a y , Ha Npi Email: n h i e m d n @ i m s . v a s t . a c . v n Dien thoai: 0 4 6 6 7 4 7 8 1 6 .