MSEPCTBiHcoNG NGHE
SI. 'il 35
S l - i ^^
ZEOLIT Tir TRO THAN BAY: TONG HOP VA OAC TRl/NG
ZEOLITES FROM FLY ASH; SYNTHESIS AND CHARACTERIZATION
Nguyen Thi Hong Hanh, Nguyen Thi Thanh Mai
Tom tat
Tro than bay duoc xiJ ly thuy nhiet bang dung dich NaOH 3,SM. Trong qua trinh tU ly cac tinh the zeolit il duoc hlnh thanh, mot so dac tinh ciia tro bay thay doi dang ke: Dien tich be mat rieng, kha nang trao doi cation, khoi lUffng rieng, dien tich be mat vi lo, the tich vi lo.., Dien tkh be mat rieng tang tif 8,12m'.g-' (Ie'n45,8m^g-', Kha nang trao ddi cation tang tLr21mmol/100g den 300mmol/100g.,. Bay la mot phuong phap dOn giin va hieu qui d l c3i thien boat tinh cua tro than bay.
Abstract
Coal fly ash was modified by hydrothemial treatment with 3.5M NaOH. During the modification the zeolites v/ere synthesized. The modification activated the fly ash significantly with respect to specific surface area (SSA), cation exchange capacity (CEC), density, surface area of micro-hole,.. SSA increased fiom 8.12m^g-' to 4 5 , 8 m V ' CEC rose from 21mmol/100g to 300mmol/100g... This is a simple and effective method to improve the activity of coal fly ash
ThS Nguyen Thi Hong Hanh,
Khoa lai nguyen v^ Moi tnfdng, TrUimg M hoc Nong nghidp Ha Noi TS. Nguyen Thi Thanh Mai
Khoa Cdng nghe H6a tiocTnfcing^ai iioc Cong nghiep Ha Noi Email:,
Ngay nhan bai: 25/0S/2013 Ngiy chSp nhan dang: 05/08/2013
l . D A T V A N O i
Theo Lyer va Stanmore (1995), tro bay la cac hat rSn, khong bi dot chay va dLfac thoi ra cung vdi khi 16 trong cac 16 dot dung than la nhien lieu.
Thanh phan chili yeu cCia tro bay: SiOj (40 - 65%), A\p^ (20 - 40%), va mot so cac oxit khac co ham luang nh6 han nha: Fep^ (5 - 10%), CaO, MgO, Na^O, KjO, (VlnO, TiOj.,.. Ngoai ra con mpt sd nguyen to cf dang vet nhif: As, Cd, Zn, Cu, Se, Cr...
Thanh phan khoang hpc cua tro bay gom: Quartz (SiO^), Mulit (2SiO^ -i- 3AiPj) va dang v6 dinh hlnh. Co the xem tro bay nha la nhom silicat v6 djnh hinh va co chu'a tap chat. Cac loai tro
bay cd dp mjn cao. Kich thudc hat tCf 1 - lOOum, trung binh20|im.
Theo Lyer va Scott (2001) hang nam, mpt Icfpng ldn tro bay dufpc tao ra tLf qua trinh dot chay nhien lieu than da hay than bot, dac biet la cac nha may nhiet dien - nai tieu thu mpt lupng Idn than da. Nam 2000 tong lupng tro bay tren the gidi la 460 trieu tan/nam. 6 nUdc ta, lupng tro bay cung tuong doi ldn va no dupc xem nhu mot trong nhCfng tac nhan gay 6 nhiem moi trUdng. 6 cac nha may nhiet dien ham lupng SiOj trong khong khi cao anh hudng nghiem trpng den sUc khoe cua con ngudi mac du da dUoc han che bang cac bien phap nhU gian phun
nUdc, thiet bj hut bui tinh dien.
Julia (1998), Andres (1997), Querol, Plana (1997) trong thUc te chi c6 khoang 10 - 20% luong tro bay duoc tai sir dung trong cac s^n pham xay dung thdng thudng nhU: Lam phu gia cho xi mang, c h i t lieu cho be tong nhe, c l i tao dat bien, co djnh cac nguyen to doc hai... gop phan lam giam lupng tro bay thai ra moi trudng. d Anh, lupng tro bay sinh ra hang nam khoing 10 trieu tan va dupc sCf dung lai khoing 1 tri&u tan. d Australia, thai ra 8 trieu t^n va sa dung lai 1 tri^u tan. d My (1990) thai ra khoang 50 trieu tan va sii dung lai khoang 10 trieu tan. 6 Viet Nam, trfi lupng tro bay d mpt s6 nha may nhiet dien: Uong Bi 2 - 2,1 tri&u tan; Phi Lai 3,8 • 4,8 trieu tan; Thai Nguyen 1 -1,2 trieu tan; Viet Tri 0,9 - 1 trieu tan; Cac nha may khac 2,3 - 3 trieu tan. Nhu vay mac du da dUpc thu hoi va stf dung nhUng lUpng tro bay t h l i ra van I6n han rat nhieu so vdi khoi lUpng t l i si^
dung. Luang tro bay ton trCt lai lam Inh hudng ldn den moi trUdng song ciii con ngudi, gay ra nhUng ganh n?nc Idn ve kinh te va mdi trUdng. Di^u na) da thuc day cac nha nghien cUu tin kiem cac phuang p h i p sil dung tro ba;
vao cac muc dich khac nhu che tao v^
lieu mdi, vat lieu hap phu va xut ly m£
trudng, xCr ly ric t h l i va Ung dung ci tao dat trong ndng nghiep. Trong de ti n i y chung toi nghien cUu chuydn hoa
54,TapdiiKHOAHOC&CONGNGHE. So 1 8 . 2 0 1 3
SClENCETECHNOLOGYl
tro than bay thanh vat lieu zeolit 2. V A T L I E U V A PHl/ONG P H A P NGHISN cau
Tro b a y d U p c lay v e t U b d Ipc t i n h
^ e n n h a m a y n h i e t d i e n PhS L a i . D u n g sang ray lay t r o b a y c o c d h a t n h o h a n 45Mm. Sau d o c h o 3 0 0 g t r o b a y v a o b i n h c a u . T h e m v a o 7 0 0 m l d u n g d j c h N a O H . L i p s i n h h a n h o i l u u , n h i e t ke, O u n h 6 i l u u d 8 0 - g C C . Loc, rUa h 6 n h o p d u n g d j c h chUa t r o b a y d e n p H = 8. Say k h o .
- K h I o s a t I n h h U d n g c u a n o n g d p NaOH d e n h i e u q u i c h u y e n h d a z e o l i t , t h d i g i a n g i a h o a 2 4 g i d .
N o n g d d d u n g d j c h N a O H 1,5IV1
2 M 2,5IV1
3IV1 3 , 5 M 4IV1
Bang I.Thanh phan khoi lifong ciia tro bay is nha may nhiet dien nhiet dien Pha Lai Thanh phan
Ham luang [%) SiOi 40,41
AtO, 13,77
CaO 1,85
Fe;0, 7,30
MgO 1,40
NaiO 0,36
LOI- 28,1
- KhIo sat anh hudng cua thdi gian gia hoa den hi#u q u i chuyen hoa zeolit, nong dp NaOH 3,5IV1.
Thdi gian chuyen hda Ki hieu mau
12 gid Zeolit-12G 18 gid Zeolit-18G 24 gid Zeolit-24G 30 gid Zeolit-30G
hai nudc khoing ISgid, dem can xac djnh khoi lupng m^. Lupng nudc hap thu (%) dupc tinh theo cong thdc;
m^^(%) = (m^-m,).100/mO Tien hanh xle dinh dien tich be mat rieng, dien tich be mat vi Id, the tich vi Id tren may Autosorb-2, Phong thi nghiem Hoa dau - Khoa Hoa - Dai hpc Khoa hpcTUnhien-Ha Npi.
Xac djnh kha nang trao ddi cation (CEC - Cation Exchange Capacity) b i n g phuang phap amoni axetat.
KhIo sat thanh phan va cau true tinh the cua Zeolit b i n g phuong phap nhieu xa Rang hen tren may D8 Advanced (Buker-DUc) vdi ong phat xa tia X b i n g ddng, bUdc sdng Ka
^ 1,5406A'', gdc quet 29, tdc dd quet 0,20/s.
Ki hieu mau Zeolit-l,5M Zeolit-2M Zeolit-2,5IVl
Zeolit-3IVl Zeolit-3,5M
Zeolit-4M
So sanh sUthay doi khdi lUpng rieng cua tro bay trudc va sau khi xU ly thuy nhiet vdi NaOH: Lay mot lUpng the tich chinh xac (V) vat lieu tro bay chua xU ly.
Can xle dinh khdi lupng m,. Lay chinh xac V the tich tro bay sau xCf ly NaOH.
Can xle djnh khoi lUpng m^. TU m,, V tfnh dupe khoi lupng rieng eua vat lieu chUa xU ly(d,),TUmj,V tinh dupe khoi luong rieng cua vat lieu da xU ly (d^). So s i n h d , vad^.
Khi nang hap thu nUdc:Ti^n h l n h can mo gam zeolit cho vao coc chiu nhi^t, say chan khdng d 160-180°C khoing 6gid, de ngupi ve nhiet dd phdng, dem can xac djnh khoi lupng m . Bat mau vao binh kin cd bao h o i
Chup anh tren kinh hien vi dien tU quet (SEM) tren may SEM-JEOL-JSIVl 541OLV (Nhat) - tai Khoa Vat ly - TrUdng Oai hpc Khoa hoc TU nhien- Ha Npi.
B.KeTQUAVATHAOLUAN 3.1 Thanh phan hoa hoc cua tro bay
BSng 2, Ket qua xac dinh mgt so thong so vat ly
Thanh phan hda hpc eua mau tro bay nha may nhiet dien Phi Lai dung trong nghien cUu dUOc phan tich va dua ra trong b i n g 1.
*Lost of Ignite (LOI): Thanh phan khoi luang bj mat di khi nung
NhUvay, thanh phan chu yeu cCia tro bay la eac oxit SiO^ va AI^O^, la cae thanh phan oxit cau true nen zeolite. Vdi ty le SiOj/AiPj = 3, phu hpp lam nguyen lieu dau cho qua trinh tong hap zeolite.
3.2. Ket quci xac cTmh mot so thong so vat ly cua tro than bay va cac mau zeolit.
Tii ket q u i thu 6MC (bang 2) cho thay, nong dp NaOH 3,5M va thdi gian xd ly 24 gid cho hieu qua ehuyen hoa tot nhat, Tro bay sau khi xd Ij? b i n g kiem (cac mau zeolite) ed khoi lupng ri^ng g i i m khoang 1,57 lan so vdi tro bay chua xd ly, dien tich be mat Idn hOn 5,64 lan, cd sU xuat hien cac vi 16, Bieu nay cd the g i l i thich ia do sU hoa tan cua mpt sd oxit kim loai va do sU djnh hinh khung cau true tao cac vi 16, lam tang dien tich be mat rieng va g i i m khdi luong rieng, Bong thdi cic vi 16 eung la yeu td quyet dinh tdi ket q u i eija qua trinh hap phu.
Vat lieu Tto than bay Zeolit-l,SM Zcolit-2M Zeolit-2,SM Zeolit-3M Zeolit-3,5M Zealit-4M Zen!it-12G Zeolit-18G Zrollt'24G Zeollt'SOG
Khoi li/ong rieng (g/cm') 0,77 0,68 0,52 0,50 0,49 0,49 0,49 0,71 0,63 0,49 0,49
Dien tich be mat rieng
ImVgl 8,12 8,80 10,06 25,71 36,16 4S,80 4«,10 12,61 35,24 46,20 46,13
Dien ti'ch be matviio
(mVgl 0,00 0,08 0,75 1,03 1,27 1,78 1,78 0,61 1,03 1,78 1,77
Thetith viio (ral/g) 0,0000 0,0000 0,0002 0,0003 0,0005 0,0006 0,0006 0,0001 0,0003 0,0006 0,0006
CEC (mmot/lOOg)
21,23 22,41 75,63 151,53 268,62 300,56 310,04 60,92 204,59 321,64 325,16
c A I Q o n i 3 . Tsn^i'i/ur^Aunrfi.rhMCKinuC c c
EEaEHCONGNGHE.
"^tia ^ 'iLv 'uj
Hinh 1, Gian 66 nhi^u xa tia X cua tro bay (mau ZeTH2) va mau Zeolit-3,5M (mau ZeTHI 2)
Hinh a; Tro bay Hinh b: Zeolit -3,5M Hinh 2, Hinh anh chup tren kinh hien vi 3ien til quet cua tro bay (a) va Zeolit-3,5M [b)
Bang 3, Ket qua xac dmh luong nudc hap phu STT Khoi luong
mau dem hap phu (mO)
Khoi lugng coc va mautnrdchapphu
( m i l
Khoi luong coc va mau sau hap phu
(m2)
Luung nudc hap phu(%)
Tro bay 1
2 3
0,8655 0,9143 0,8346
18,8913 18,8758 18,8719
18,9481 18,9352 18,9265
6,5644 6,4998 6,5397 Zeoiit-3,5M
1 2 3
0,7521 0,9672 1,0365
21,9757 22,8523 22,1368
22,0957 23,0073 23,3041
15,9553 16,0355 16,1425
3.3. Phan tich dac trumg cau true cua tro bay va m l u Zeolit-3,5M bang phUtfng phap nhieu xa Rtfnghen
Ket q u i ghi mau nhieu xa Ranghen cua than tro bay trudc va sau xU ly NaOH cua nha may nhiet dien Pha lai.
Phuang phap nhieu xa Rdnghen eho phep p h i n loai cac dang cau true tinh the Zeolit, phat hien tinh the pha tap va danh g i l mUc dd ket tinh. Phd do nhan
duoc cho thay ngay ca trong mau trudc khi xis ly kiem dang tinh the da ton tai ben canh cau true v6 dinh hlnh. Sau xU ly kiem va nhiet pha tinh the mdi dupc hinh thanh va cho eac pic mdi cd cUdng dd manh hon (gpi la qua trinh ket tinh thuyf nhiet tao mam va gia hoa). Theo ket q u i phan tich, pha tinh the mdi hinh thanh la dang Natri aluminium silicate hydrat vdi t^ le SiO/MjOj = 2,5.
NhUvay san pham tao thanh la cac hap chat zeolit.
Gian do nhieu xa tia X (hinh 1)chD tha'y, thanh p h i n tinh the trong san pham kha phUc tap, tro bay trLfdc khi ly kiem chi co quartz va haloysitecoo lai la cac dang vd dinh hlnh, tro ba) sau xU ly kiem cd rat nhieu loai tinl the va zeolit dupc hinh thanh. Thee Lyer (1995, 2001), Woolard (2000), tn bay trUdc xd iy kiem co cau tao tiS cSi nguyen to Si va AI d dang lien ketbi dien vdi 6 nguyen tU oxi. CJ trang tha nay tro bay cd kha nang trao doi catioi (CEC) thap va phu thupc vao pH, pi cang cao thi CEC cang cao va ngUOclj Tuy nhien, d pH cao thi da so cac kir loai nang deu ket tua do vay khi nan hap phu va Ung dung eua tro bay chu xLflycon han che.
Be khac phuc han che nay, tro b;
dupc xd ly bang NaOH 3,5IV1 d nhietd cao, tU 80 - gCC. Ket qua la lam thayd cau true cO ban cua zeolit tU cau tn b i t dien thanh cau true tU dien [SiO [AlOJ - vdi dang eau true nay zeolit ti thanh cd nhieu uu diem: chuyen trang thai tro than v6 dinh hinh thai zeolit tinh thi. zeolit tao thanh co C cao va khdng phu thudc vao pH.
3.4. Ket qua chup hinh I n h tr kinh hien vi d^ i - qugt
Hlnh I n h k^t qua chup tren kl h i l n VI dien tUquet (SEM) dp phong
5 6 Tap dii KHOA HOC & CONG NGH| • So 1 8 . 2 0 1 3
SClENCETECHNOLOGYl
Phuong trtnh hS'p phu dang nhift Langmuir (Zn^"^) q = qmat Ka C^Cl+Ka Cf)
Cf(mg/1) Hlnh 3.
^5000 lan cua mau zeolit tdng hpp thay jtrong mau cd cic pha tinh the dupc tao jthanh, kich thudc hat khoing 0,5pm i(hlnh2).
, Nhu vay b i n g phuang phap ket itinh thuy nhiet da thu dupe san pham zeolit tU tro than bay cd cau true tinh ,thl, CO su xuat hien eac vi 16, tang dien iti'eh b l mat rieng.
3.5. Ket qua xac dinh iUtfng midc hap phu trong tro bay va zeolit (bang 3}
IVIau zeolite-3,5IVl ddpc hinh thanh CO cau true tinh the, cd dien tich be mat rieng Idn, the tich vi Id Idn nen cd kha nang hap phu mot lUpng nudc Idn hOn so vdi cic mau tro bay. Day la cO sd eua qua trinh hap phu va trao doi ion eCia cicvat lieu zeolit.
3.6. Khao sat k h i nang hS'p phu kem cua zeolite
Mo hinh hap phu dang nhiet Langmuir kha phu hpp vdi ket qua thi nghiem, cd the sCf dung de khIo sat k h i nang hap phu ion kim loai phu zeolit. He sd hoi quy cCia md hinh hap phu vdi kem 11 0,989. Ket qua da cho
tha'y zeolit cd k h i nang hap phu tuang ddi Idn, tai trpng hap phu cue dai q^^^ - 16,13mg/g vdi kem (hlnh 3).
4. K^T L U A N V A Kl^N NGHj - Hieu qua cua qua trinh chuyen hda tot nhat d dieu kien nong do dung dich NaOH 3,5M, thdi gian ehuyen hda 24 gid,
- Mau zeolit tdng hop dUOc cd dien tich be mat rieng khoing 45,8m^.g"', dien tich be mat vi 16 khoing 1,78mVg, k h i nang trao doi caction khoing 300 mmol/IOOg. Cd kha nang hap thu tdt nudc (16%), hapthu kem (16,13mg/g).
Phin bien khoa hoc: TS. Vii Minh Tan
TAI LIEU THAM KHAO
[1]. Bao cao tong ket hoi nghi cong doan nha may Nhiet diln Pha Lai, 2009.
[2]. R,S. lyer and B.R. Stanmore; Surface area of fiyashes; Cement and concrete Research, Vol. 25, No.
7,pp 1403-1405,1995
[3]. RS.Lyer, J.A. Scott; Powet station flyash - A review of value-add utilization outside of the contruction industry; Resources, Coservation and recycling31(2001)pp, 217-228.
[4j. Julia Ayala. et; Asturian flyash as a heavy metals removal material; Fuel, Vol. 77 , No. 11, pp 1147-1154,1998.
[5]. Tose. (1/1. Andres, Roberto Juan; A fest method for recyding flyash' Microwave- Assisted zeolit synthesis;
Enviran. Sci.Technol 1997 31, pp 2527- 2533.
[6]. Xavier Querol, flecia plana; Synthesis of Na- Zeolite from flyash; Fuel, Vol. 16, No. 8, pp 793-799,1997.
[7]. CD Woolard, K. Petms and M. vander Horst, The use ofa modified flyash as an adsorbent for lead,;
ISSN 0378- 4738; Water SA Vol. 26, No. 4 October 2000.
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