TAP CHI HOA HOC T 49(4) 489 493 THANG 8 NAM 2011 ANH HU''''6''''NG CUA MOT S6 Y^U T 6 D^N QUA TRJNH XU'''' LY CONGO D6 B A N G PHU''''aNG PHAP FENTON DIEN HOA Pham Thi Minh'''', Nguyen Thj Le Hien^ Dinh Thj Mai Than[.]
Trang 1TAP CHI HOA HOC T 49(4) 489-493 THANG 8 NAM 2011
ANH HÚ6'NG CUA MOT S6 Y^U T 6 D ^ N QUA TRJNH XÚ LY CONGO D6
Pham Thi Minh', Nguyen Thj Le Hien^ Dinh Thj Mai Thanh', Thai Hoang'
Vi^n Ky thudt nhiqt d&i ~ Vi^n Khoa hgc vd Cdng ngh? Viqt Nam
^Chi nhdnh Vien Ddu khi Viet Nam - Trung tdm Ifng dung vd Chuyen giao cdng nghe
Den Tda soan 17-6-2011
Abstract
This paper presents results electro catalysis ability by redox reaction create H2O2 of Carbon (C), C/Ppy, C/Ppy(oxit) materials and influence of nature of cathodic material, current density, concentration ratio between red Congo and iron (II) ion on red Congo treatment by electro-Fenton process The results showed in axit environment pH = 3 C/Ppy(oxit) electrode had the highest removal efficiencỵ The decrease of red congo concentration in treatment process was determined by UV-vis spectra method and COD indicator The prelimilary data indicated that using Ppy/CU| sMni 5O4 cathodic electrode, at 1 mA/cm^ density, ratio CcR/CFế^= 0.25 mM/1 mM, the disintegrating efficiency of red Congo reached'over 70% after 7-hour treatment with current efficiency over 100%
ỊMQDAU
Trong nhifng nam gan day, vifc nghifn eiiu xu ly
nudc thai chiia cac hgp chat tgo mau hg azo (congo đ,
methyl da cam, metyl đ ) dang dugc nhifu nha khoa
hpc frong va ngoai nudc quan tam nghifn cuụ Fenton
difn hoa la mdt gong eac phuong phap oxi boa tifn
tien cho phep oxi boa khdng chgn Ige eae hgp chat hiru
CO đc hai khd phan buy dang duge ap dyng rdng rai
gong xir ly nude thaị
Trong phan iing Fenton difn hda, H2O2 dxxqc
sinh ra bang each khu hai electron cua oxi trfn
mpt sd difn cue nhu cacbon kfnh, graphit, difn
cue khuech tan khị [1 3]
O2 + 2e + 2H2O -^ 2H2O2 (1)
H2O2 hinh thanh tac dyng vdi mdt lugng nhd chat
xiic tac Fê"" dugc thfm vao frong dung djeh tao thanh
gdc OH* ed kha nang oxi hda hau hft cae hgp chat hum
CO (RH) theo phan iing sau:
Fê + H2O2 + H ^ ^ O H ' + Fê^ + H20 (2)
Fê^ + H2O2 ^ Fê^ + H02* + H^ (3)
OH* + R H ^ R * + H 2 0 (4)
Hifu suat khoang boa eae hgp chat hiru co phy
thude vao chf do difn boa, ban chat ciia eac chat d
nhiem, pH eua dung djch va dae bift la vat lifu difn
cue andt va eatdt Cae nghifn ciru trudc day cua
chiing tdi da chi ra ring hifu irng Fenton difn hda
cho phep khoang hda hoan toan eac hgp chat mau
tdng hgp nhu metyl da cam, metyl đ vdi hifu suit
đng cao trfn difn cgc eatdt nen cacbon phu
compozit Ppy(oxit) Trong khudn khd bai bao nay, chiing tdi nghifn cuu khao sat anh hudng cua ban chat vat lifu eatdt, mat dp đng ap dat, ndng do congo đ dfn qua trinh xu ly congo đ bang hifu ung Fenton difn hoạ
2 DIEU KIEN THI/C NGHIEM Qua trinh tdng hgp mang polyme dan trfn difn cgc cacbon (C) dugc thgc hien trong binh difn hda
hf ba difn cgc vdi difn cgc lam vifc la cacbon dgng hinh try, xung quanh phu epoxy sao cho dien tfch lam vifc khdng đi bang 5 cm^; difn cgc đi la ludi platin va difn cgc so sanh la ealomen bao hda KCl tren thiet bj Autolab (Ha Lan) dgt tgi Vifn Ky thuat nhift đi, trong dung djch KCl 0,5 M chiia pyrrol 0,1 M ed va khdng ed oxit Cui_5Mni_504 tdn tgi dudi dgng huyfn phii trong dung djeh nhd khuay tir
Kha nang xiie tac difn hda ciia cae ldp phu polyme dan duge danh gia bang phuomg phap difn the dirng trong 50 ml dung djch Na2S04 0,05 M d
pH = 3, cd va khdng sye oxị Trong phep do nay, difn thf duge ap dgt tir difn thf mgeh hd vf phfa catot vdi bude nhay thf 100 mV, thdi gian cua mdi budc nhay thf dugc ap dgt trong khoang 1000s
Qua trinh xir ly congo đ duge thue hifn trong
hf hai difn cgc bing phuomg phap đng ap dgt (galvonostatie) vdi eae mat dp đng la 1; 5; 10 mA/cm^ trong dung djch Na2S04 0,1 M, pH = 3 chiia Fê"^ 1 mM, ndng dp congo đ (C32H2206N6Na2S2) la 0,5 mM; 0,25 mM va 0,125
mM, duge sye khi oxi vdi tde do 0,5 l/phut
Su suy giam ndng do congo do trong qua trinh
489
Trang 2TCHH, T 49(4), 2011 Dinh Thi Mai Thanh vd cgngsu
xir ly dugc nghien cum bing phd UV-vis tren thiet bj
UV-speetrometer, Citra 40-My, tgi Vifn Ky thugt
nhift ddi Hifu suit phan buy duge tinh theo cdng
thiic [4]:
il( %)
=-A., - A
.100%
Trong dd: i]: I lifu suit phan huy (%); AQ: cudng dg
hip thy tgi thdi diem ban diu; A,: eudng dg hip thy
tgi thdi diem t
Sg phan huy congo dd trong qua trinh xir ly
dugc xac djnh thdng qua nhu clu oxi hda hgc
(COD), xac djnh bing each sir dyng lugng du ehat
oxi hda mgnh K2Cr207 vdi xuc tac Ag2S04 Lugng
K2Cr207 ban diu va lugng du sau khi oxi hda hoan
toan cac hgp chat hiru co dugc chuan dg bang muoi
Morh vdi chi thj diphetylamin
Hifu suit ddng difn cua qua trinh xir ly (H)
dugc tinh theo cdng thire [5]:
H(%)
Vdi: AcoD - Dg bi^n thifn chi so COD (^1), V Thf tfch dung djch difn phan (1), F Hing so Faraday, Q Difn tfch qua binh (C)
cac hda chit sir dyng trong nghien ciru nay deu
cd dg tinh khiet cao (PA)
3 KET QUA VA T H A O LUAN
3.1 Kha ndng xiic tac difn hoa cua mang Ppy(oxit) cho phan irng khir oxi tao hidro peoxit tren difn cgc catot graphit
Ket qua do kha nang xiic tae difn hda ciia ba loai vgt lifu difn cgc C; C/Ppy va C/Ppy(oxit) dugc bifu dien tren hinh 1 Tir do thj cd thf nhgn thay mat dp ddng eatdt cua difn cgc C/Ppy(oxit) ludn dgt gia trj cao nhat Dieu do chirng td kha nang xuc tac cho qua trinh khir oxi hda tan tgo H2O2 cua difn cue C/Ppy(oxit) la Idn nhit va md ra kha nang irng dung vat lifu difn cgc nay trong xir If mdi trudng bang phuong phap Fenton difn hda
-0.8
E
0
0 0
0 2
0 4
0 6
0 8
-•—
•
•
— • — • — •
^ •
— • — • • s
- - - • — ^ ^ ' " " ' ^
—•—c
— • — C / P p y
- A - C / P p y ( C u , 5 M n , , 0 , )
1 1 •
E(V/SCE)
Kmh 1: Mat do ddng catot tgi cae difn the ap dgt trong dung djeh pH = 3
3.2 Anh hirdng ciia vat lieu catot
3.2.1 Ket qud do pho UV-Vis
Sg suy giam ndng do va bien thifn hifu suit
phan hiiy congo dd 0,25 mM trong qua trinh xOr ly
nhd hifu ling Fenton difn hda d\xcsc bieu dien tren
eac hinh 2 va3
Phd UV-vis Clia congo dd tgi pH = 3 trude khi
xur ly duge dae trung bdi mdt dai phd trong viing
nhin thay vdi cgc dgi hap thy d 560 nm Doi vdi ca
ba logi difn cgc tgi mat do ddng 5 mA/em^, cudng
do pic tgi 560nm deu giam dan theo thdi gian xii ly
tuomg limg vdi sg phan hiiy clu triic -N=N- din tai lam giam dan ndng dg congo dd trong dung dich difn phan
Ket qua xac djnh sg bifn thifn hifu suit phan hiiy Congo dd cho thiy: Sau 7 gid difn phan hieu suit phan hiiy dgt 32% doi vdi difn cgc C; 42% dfi vdi difn cgc C/Ppy va 65% doi vdi difn cue C/Ppy(Cui,5Mni,504) Dieu nay khing djnh qua trinh xir ly Congo dd 0,25 mM nhd hifu iing Fenton dien hda sii dyng difn cgc C/Ppy (Cui.jMn 1,504) d mat do ddng 5 mA/cm^ cho hifu suit cao hon ca do kha nang xiic tac tot cua loai difn cue nay ddi vdi qua trinh khu oxi hda tan tao H262
490
Trang 3TCHH, T 49(4), 2011 Anh hu&ng cua mgt so yeu td den
- T - c
—•—C/Ppy
—• —C/Ppy(oxit)
200,0 300,0
Congo nJ
I I I I I I I I I I I I I I I
6000 7000 800.0
t(h)
LTinh 2: Phd UV-vis cua congo dd theo LTinh 3: Bien thifn hifu suit phan hiiy congo dd 0,25 mM
thdi gian phan hiiy tgi mat dp ddng
5mA/cm", trfn difn cgc catot C/Ppy((oxit)
3.2.2 Ket qud xdc djnh COD
Bfn cgnh ket qua thu duge bing phuomg phap do
UV-vis, dung djch congo dd sau difn phan cdn dugc
dem phan tich COD df xac djnh do suy giam chi so
COD theo thdi gian xir ly va bien thien hifu suat
ddng difn khoang hda congo dd (hinh 3, 4) Ddi vdi
ca ba trudng hgp su dung difn cgc eatdt C; C/Ppy;
C/Ppy(oxit), do suy giam COD deu tang din theo
thdi gian difn phan Sau 7 gid xu ly do suy giam
COD dgt 180 dom vj COD ddi vdi trudmg hgp su
dung difn cue eatdt C; 210 don vj COD ddi vdi
trudng hgp dimg difn cgc eatdt C/Ppy va 240 dom vj
COD ddi vdi trudng hgp diing difn cue eatdt la
theo thdi gian tgi mat do ddng ap dgt 5 mA/cm
C/Ppy(oxit) Mgt lin nira khang djnh rang tgi eiing mdt thdi difm gia trj difn lugng Q nhu nhau nhung khi sir dung difn cgc eatdt la C/Ppy(oxit) vdi tfnh nang xuc tae tdt cho qua trinh khir oxi hda tan tgo H2O2 da lam tang toe dp cua qua trinh oxi hda congo
dd do dd lam cho dp suy giam COD cao hon so vdi khi sii dyng difn cgc C va C/Ppy KSt qua xae djnh hifu suat ddng difn khoang hda congo dd eung cho thiy khi sir dyng difn cgc C/Ppy(oxit) trong qua trinh difn phan tgi nhung thdi difm ban dau sau
1 gid difn phan hifu suit ddng dgt 130%) cao hon so vdi trudng hgp su dyng difn cue C/Ppy vdi hifu suat ddng 104%) va cao hon nhieu so vdi khi sii dyng difn cue C vdi hifu suit ddng ehi 65%)
250
(a)
150
120
l '
- A - C
— • — C/Ppy
—•—C/Ppy(oxit)
4
t(h)
(b)
LTinh 4: Do suy giam COD (a) va hifu suit ddng (b) trong qua trinh
phan hiiy congo dd 0,25 mM theo thdi gian tgi mat dg ddng ap dat 5 mA/cm
3.3 Anh hirdng cua mat do dong
Anh hudng eiia mat do ddng dfn qua trinh xu ly
difn hda congo dd dugc chi ra tren cac hinh 5 va 6
Ket qua cho thiy tgi mat do ddng 1 mA/cm^ d cac
thdi diem khac nhau khi cd ciing gia tri difn lugng Q
chuyen qua hifu suit phan buy va do suy giam COD ludn dgt gia trj eao hon so vdi trudng hgp difn phan
tgi mat do ddng 5; 10 mA/cml 6 gia trj difn lugng
Q = 2 A.h/1 hifu suit phan hiiy tgi cae mat do ddng 1 mA/cm^; 5 mA/cm^; 10 mA/cm^ dgt eae gia trj lin lugt la: 75%; 42% va 34%; do suy giam COD eung
Trang 4TCHH, T 49(4), 2011
giam din theo trgt tg: 280 don vj COD (d
ImA/cm^); 240 don vj COD (d 5 mA/cm^); 210 don
vjCOD(dl0mA/em^)
Ben canh do tai nhung thdi diem ban dau cua
qua trinh difn phan, hifu suit ddng difn phan hiiy
dat gia trj kha cao duge ly giai la do cd sg tham gia
eiia hifu irng Fenton difn hda nen xay ra nhieu qua
trinh ddng thdi nhu: oxi hda trgc tiep congo dd trfn
dien cgc andt, oxi hda gian tiep congo dd trfn difn
cue eatdt nhd cae tac nhan oxi hda mgnh gay ra,
Mat khac eac qua trinh xay ra tren be mgt difn cgc
tao ra cac tac nhan oxi hda mgnh cd kha nang oxi
hda hoan toan congo dd va cae hgp chat trung gian
dan den hifu suit ddng difn dgt gia trj rat eao, dae
biet trong trudmg hgp sir dung dien cue eatdt la
C/Ppy(oxit) d mat dp ddng 1 mA/em^ hifu suat ddng
dat gia trj kha cao tdi 157,6% khi Q = 0,25 A.h/1
Dinh Thi Mai Thanh vd cgngsy
3.4 Anh hu-dng ciia nong dg congo do
Ket qua phan tfch pho UV-Vis va xac djnh COD trong qui trinh xu If congo dd d cac ndng dg khac nhau, tgi mgt dg ddng 1 mA/cm^ trong dung djch Na2S04 0,1 M, pH = 3 chira Fe^^ 1 mM dugc bifu dien trfn hinh 7 va 8 Tir do thj cd the thiy ring vdi eiing ham lugng ion Fe^"^ trong dung djeh difn phan, khi nong dg congo dd giam din (tir 0,5 mM den 0,125mM) hifu suit phan buy tuong img tang din Tuy nhien hifu suit ddng difn phan buy congo do 0.25mM dgt gia trj cao nhat 157,6%) so vdi hai trudng hgp nong dg 0,5 mM (78,8%) va 0,125 mM (52,5%) sau I gid difn phan Dieu nay chirng td rang ti If ve nong dg giifa congo dd va ion Fe^^ cd vai trd quyet djnh den hifu suit cua qua trinh xir ly congo dd Theo
dd ti If giira nong dg congo dd va nong dg ion Fe^^ bing 0,25:1 se cho hifu qua xir ly cao hon ca
80
-•— 1 mA/cm
-•— 5 mA/cm
-A— 10 mA/cm'
LTinh 5: Bifn thien hifu suat phan huy congo dd
0,25mM theo dien lugng Q, sir dung difn cgc
catot C/Ppy(oxit)
Hinh 6: Dg suy giam COD va bifn thien hifu suat
ddng difn phan hiiy congo dd 0,25 mM theo Q tren
catot C/Ppy(oxit)
45
30
15 •—O.SmM
-•—0.25mM
-A-0.125mM
A
•
A
^A • ^A
-4 t(h)
120-^
•
80-
4
0-*
•^,
• ^
^~~"A
U
^^«
~ ^ B —
• ^
• —
^ • ~
— A
— •
-—•— O.SmM
—•— 0.25mM
—A—0.i25mM
4 t(h)
LTinh 7: Bien thien hifu suat phan buy congo dd
theo thdi gian tgi mat do ddng 1 mA/em^ tren catot
C/Ppy(oxit)
LTinh 8: Su bifn thien hifu suit ddng difn phan
buy congo do theo thdi gian, tai mat dg ddng
1 mA/cm^ tren catot C/Ppy(oxit)
AQ'-)
Trang 5TCHH, T 49(4), 2011
4 KET LUAN
Khing djnh duge kha nang xiic tae tot cua mang
compozit Ppy(oxit) doi vdi qua trinh khii oxi hda tan
tgo H2O2 lam tang dang ke hifu qua frong xir ly
nudc thai bang hifu dng Fenton difn hda
cac ket qua thu dugc cho thay hifu ung Fenton
difn hoa cd kha nang phan hiiy hifu qua congo do
ndng do 0,25 mM tgi mgt dg ddng 1 mA/cm trfn
difn cgc eatdt C/Ppy(oxit) trong dung djch Na2S04,
pH = 3 cd mat ion Fe^^ 1 mM dugc sye khf oxi Q
difu kifn nay sau 35 gid xu ly, hifu suat phan hiiy
congo dd dgt 75%o Cac kft qua xac djnh COD cho
thay theo thdi gian difn phan COD giam din, sau 7
gid difn phan chi so COD da suy giam tir 320 mg/l
xudng cdn 40 mg/l dam bao du tifu chuin thai ra
mdi gudng hoge sir dyng trong tudi tifu, frong trgt
Hifu suit ddng difn tuomg ung rit ldm, dgt gia trj
Anh hu&ng ciia mgt sd yeu td din
157,6%) sau 1 gid xir ly
TAI LIEU THAM KHAO
1 D A Pozzo, L D Palma, C Merli, E Petrucci J Appl Electrochem., 35, 413 (2005)
2 A A Gallegos, P Pletcher Electrochim Acta 44 (1998)853
3 Z M Qiang, J H Chang, C P Huang Water Res.,
36, 85 (2002)
4 Minghua Zhou, Qinghong Yu, Lecheng Lei, Geoff Barton Separation and Purification Technology, 57,
380 - 387 (2007)
5 Nguyen Hong Thai Nghien ciiu tong hgp difn cue mang compozit tren ca sd polyme dan difn va oxit phijc hgp nhim umg dung nhu difn cgc xiic tac dien h6a xu ly m6i trudng, Luan vSn thac sT h6a hpc, Trudng DHSP Ha Npi (2007)
Lien he: Dinh Thi Mai Thanh
Vifn Ky thugt Nhift ddi
Vifn Khoa hgc va Cdng nghf Vift Nam
18 Hoang Quoc Vift, Clu Giiy, Ha Ndi
493