Xử lý Congo đỏ bằng phương pháp Fenton điện hóa

Hoi nghi Khoa hoc ky niem 35 nam Vien Khoa hoc va Cong nghe Viet Nam - Ha Noi 10/2010<br /> <br /> <br /> Xtr LY CONGO DO BANG PHlTONG PHAP FENTON DIEN HOA<br /> <br /> Pham Thi Minh'. Nguyin Thj Le Hiln^ Dinh Thi Mai Thanh^<br /> 'Truong CD Cong dong HN; ^Chi nhanh Vien Dau khi VN; V i e n Ky thuat nhiet doi<br /> Email: minhcdcd73(2)vahoo.com.vn<br /> Tom tat.<br /> Congo do la mdt hgp chdt azo dien hinh dang duoc sic dung rdng rai trong cdng<br /> nghiep nhudm. Ddy Id hop chdt rdt ddc ddi vdi sire khoe con ngudi vd mdi truang<br /> sinh thdi, nd de hod tan trong nude vd khd bi phdn huy bdng phuang phdp sinh hoc.<br /> Fenton dien hod la mdt trong cdc phuong phdp oxy hod tien tien cho phep oxy hod<br /> khdng chon loc cdc hap chdt hiru ca ddc hgi khd phdn huy dang duac cdc nhd khoa<br /> hoc trong vd ngodi nude quan tdm nghien cuu. Trong khudn khd bdi bdo ndy, chung<br /> tdi nghien ciru khdo sdt dnh hudng cita bdn chdt vdt lieu catot den qud trinh xir ly<br /> congo dd bdng hieu irng Fenton dien hod. Su suy gidm ndng do cua congo dd trong<br /> qud trinh xic ly duoc xdc dinh nhd cdc phuang phdp phd UV-Vis vd phdn tich COD.<br /> Kd qud khdo sdt ban ddu cho thdy sic dung dien cue catdt Ppy/CuijMni 5O4 cho hieu<br /> sudt phdn hiiy congo dd dgt khodng /OVo sau 7h xir ly vdi hieu sudt ddng tren 100%.<br /> Abstract.<br /> Red Congo is a typical azo compound having been used the most widely in<br /> dyeing industry. This compound is very toxic to human health and eeo-<br /> environment. It is easy to be dissolved in water and difficult to be disintegrated by<br /> biological method. Eledro-Fenton is one of mordern oxidation methods which<br /> allow oxidizing toxic organic compounds non-seleetively being studied by<br /> domestic and international scientists. In this article, we investigate and survey the<br /> impact of the nature of cathodic material to Congo treatment by eledro-Fenton<br /> method. The decrease of red congo concentration in treatment process is<br /> determined by UV-vis spectra method and COD indicator. Initial result showed<br /> that using Ppy/CuijMn/jO^ cathodic catot for red congo disintegrating efficiency<br /> reached around 70%) after 7h treatment with current efficiency of over 100% .<br /> <br /> l.MdDAU<br /> Congo do (C32H2206N6Na2S2) la mot hgp chat azo dien hinh dang dugc sir dung rgng rai trong<br /> cong nghiep nhugm. Day la hgp chat rat doc doi voi siic khoe con nguod va moi truang sinh thai,<br /> no de hoa tan trong nuoc va kh6 bi phan buy bang phuang phap sinh hgc. Fenton dien boa la mot<br /> trong cac phuang phap oxy boa tien tien cho phep oxy boa khong chgn lgc cac hgp chat hiru co<br /> doc hai kho phan buy dang dugc cac nha khoa hgc trong va ngoai nuoc quan tam nghien cim.<br /> Trong khuon khi bai bao nay chung toi se trinh bay mot so ket qua xir ly congo do bang hieu<br /> ling Fenton dien hoa sir dung dien cue cacbon co phu mang Ppy va Ppy/Cu!,5Mni,504<br /> (Ppy/oxit) o mat do dong ap dat 5 mA/cm^ trong dung dich Na2S04 0,05M, Fe^"^ ImM, nIng<br /> do congo do ban ddu 0,25mM, co sue khi oxy voi toe do 0,5 l/pbiit. Ket qua dugc so sanh vai<br /> truang hgp sir dung dien cue cacbon graphit khong phu mang polime din.<br /> Trong phan ling Fenton dien boa, H2O2 dugc sinh ra bang each khir hai electron ciia<br /> oxy tren mot s6 dien cue nhu cacbon kinh, graphit, dien cue khuech tan khi... [1-3]<br /> O2 + 2e + 2H2O -^ 2H2O2 (1)<br /> <br /> 103<br />  Tiiu ban: Moi tru&ng vd Ndng lugng ISBN: 978-604-913-013-7<br /> <br /> H2O2 hinh thanh tac dung vai mot lugng nho chat xiic tac Fe ^ dugc them vao trong dung dich<br /> tao thanh goc OH* co kha nang oxy boa hau bet cac hgp chat hiju ca (RH) theo phan ling sau:<br /> Fe^ + H2O2 + H^ -> OH* + Fe^* + H2O (2)<br /> Fe^^ + H2O2 -^ Fe^^ + H02* + H^ (3)<br /> OH* + RH ^ R* + H2O (4)<br /> Sir suy giam nong do ciia congo do va hieu suat ciia qua trinh khoang boa dugc xac dinh<br /> thong qua sir phan tich COD va phi UV-vis trong qua trinh xir ly.<br /> <br /> 2. DIEU KIEN THI/C NGHIEM<br /> Cac nghien cuu dien boa dugc thuc hien trong binh dien boa he ba dien cue vai dien cue<br /> lam viec la cacbon co va khong phu mang Ppy va Ppy/oxit hinh tru, xung quanh phu epoxy<br /> sao cho dien tich lam viec khong doi bdng 5cm^, dien cue dli la luoi platin va dien cue so<br /> sanh la calomen bao hoa KCl, tren thiit bi Autolab (Ha Lan) tai Vien Ky thuat nhiet dai. Qua<br /> trinh xir ly congo do dugc thuc hien trong he hai dien cue bdng phuang phap galvonostatic<br /> voi mat do dong ap dat la 5 mA/cm^.<br /> Su phan hiiy congo do trong qua trinh xir ly dugc nghien cuu bdng phi UV-vis tren thiit<br /> bi UV-spectrometer, Citra 40-My, tai Vien Ky thuat nhiet dai. Hieu sudt phan buy dugc tinh<br /> theo cong thiic sau [4]:<br /> T1(%) = ^ " ~ ^ M 0 0 % ;<br /> <br /> Trong do: ri - Hieu sudt phan buy (%); AQ - cuong do hdp thu tai thai dilm ban ddu; At:<br /> cuong do hap thu tai thai dilm t.<br /> Sir suy giam nong do congo do trong qua trinh xir ly dugc xac dinh thong qua nhu cdu oxy<br /> boa hgc (COD), xac dinh bdng each sir dung lugng du chdt oxy boa manh K2Cr207 voi xiic<br /> tac la Ag2S04. Lugng K2Cr207 ban ddu va lugng du sau khi oxy hoa hoan toan cac hgp chdt<br /> bun CO dugc chudn do bdng muli Morb voi chi thi Diphenylamin.<br /> Hieu sudt dien cua qua trinh xir ly (H) dugc tinh theo cong thiic sau [5]:<br /> A VF<br /> H(%) = ^ " ^ -^ •<br /> 82<br /> Vai: AcoD - Do biin thien chi si COD (g/1), V - Thi tich dung dich dien phan (1), F - Hdng<br /> so Faraday, Q - Dien tich qua binh (C). Cac boa chdt sir dung trong nghien cim nay'dlu co do<br /> tinh khiet cao (PA).<br /> <br /> <br /> 3. KET QUA VA THAO LUAN<br /> 3.1 Ket qua do pho UV-Vis<br /> a. Xay dung du&ng chudn ndng dp -Cu&ng dp hdp thu UV- Vis<br /> Theo dinh lu^t Buge - Lambe - Bia, nIng do chdt hdp thu ty le thuan vai do lan cua do hdp<br /> thu A. Do do, de nghien cim s^r bien thien nIng do congo do trong suit qua trinh dien phan,<br /> chiing toi xay dimg duong chuan nIng do - cuong do hdp thu UV.<br /> De xay dung duang chudn nIng do - cuong do hdp thu UV-Vis, chiing toi tiln hanh pha<br /> mgt day dung dich chuan gom 11 mau dung dich congo do vai nIng do khac nhau sir dung<br /> dung moi pha loang la dung dich Na2S04 0,05M; pH = 3. D6 thi Hinh 1 cho thdy ro su phu<br /> thuoc cua cuong do hap thu cue dai tai buac song 560 nm va nIng do congo do la gdn nhu<br /> <br /> <br /> 104<br />  Hoi nghi Khoa hoc ky niem 35 ndm Vien Khoa hoc vd Cong nghe Viet Nam - Hd Not 10/2010<br /> <br /> tuyen tinh, tuong ling vol phuong trinh duong thdng: y = 7188,9x - 0,0786 dugc xac dinh<br /> theo phuong trinh binh phuong toi thieu co do chinh xac R^ = 0,9942. Phuong trinh nay sir<br /> dung de xac dinh nong do congo do trong qua trinh xir ly.<br /> b. Su bien thien hieu sudt phan huy<br /> Sir suy giam nong do congo do trong qua trinh xir ly nho hieu ung Fenton dien hoa dugc<br /> quan sat bang phi UV-vis (Hinh 2).<br /> <br /> <br /> <br /> <br /> R =0.9942<br /> y = 7.1889X - 0.0786<br /> <br /> <br /> <br /> C(mM)<br /> <br /> <br /> Hinh 1: Mdi quan he giira ndng do congo dd - cuong do hdp thu UV-Vis tgi buoc sdng 560nm<br /> <br /> <br /> <br /> <br /> Bien cue Ppy °^"' Bien cue Ppy/oxit<br /> Hinh 2: Phd UV-vis cua metyl do theo thdi gian phdn hiiy tgi mat dd ddng dp ddt 5mA/cm^ sir<br /> dung dien cue C/Ppy(oxit).<br /> <br /> <br /> Pho UV-vis ciia congo do tai pH3 truoc khi xir ly dugc dac trung bod mot dai pho trong<br /> viing nhin thay vai cue dai hap thu a 560nm. Doi vol ca ba loai dien cue voi mat do dong la 5<br /> mA/cm^ cuong do pic tai 560nm deu giam nhanh, tuong ung vol sir phan buy cau tnic - N =<br /> N - dan tai su mat mau dan dan cua dung dich dien phan. Ngoai ra con co mot dai pho khac<br /> trong viing tir ngoai o buoc song khoang 320 nm ngay mot tang len dugc du doan la do co su<br /> xudt hien cua san pham trung gian co chiia vong thom benzen trong dung dich co sir hien dien<br /> cua ion Fe^"^. Ket qua nay cho phep khang dinh rang trong qua trinh dien phan nh6m mang<br /> mau azo - N = N - da bi pha va dan den sir mat mau dan cua dung dich. Ket qua cua sir biin<br /> thien hieu sudt phan hiiy congo do theo thai gian dien phan dugc bieu dien tren (hinh 3).<br /> <br /> <br /> <br /> <br /> 105<br /> Tieu ban: Moi tru&ng vd Ndng lugng ISBN: 978-604-913-013-7<br /> <br /> <br /> • • " ' "<br /> eo- .m —<br /> •<br /> <br /> so- T<br /> <br /> 40- •<br /> y 30- ^•—:!=•'<br /> .—•—'<br /> 20- / • — -•- ^w—'<br /> —•—c<br /> — • — C/Ppy<br /> 10-<br /> l/y^ — • — C/Ppy(oxit)<br /> 0<<br /> ^—, , , 1 1 1 1 1 ' 1 •<br /> <br /> <br /> <br /> <br /> t(h)<br /> <br /> <br /> Hinh 3: Bien thien hieu sudt phdn hiiy congo do 0,25mM theo thai gian sir dung dien cue catot C;<br /> C/Ppy; C/Ppy(oxit) vdi mat do ddng dp ddt 5mA/cm<br /> Ket qua thu dugc da chi ra rang hieu suat phan buy congo do tang len theo thai gian dien<br /> phan. Sau 7 gia dien phan: Hieu sudt phan buy dat 33,85% doi vai dien cue C; 42,26% dli<br /> voi dien cue C/Ppy va 67,7% dli voi dien cue C/Ppy(Cui,5Mni,504). Dilu nay khdng dinh<br /> qua trinh xir ly congo do nhof hieu ling Fenton dien boa sir dung dien cue C/Ppy<br /> (Cui,5Mni_504) a mat do dong 5mA/cm^ cho hieu suat cao hon ca do kha nang xiic tac tit cua<br /> loai dien cue nay doi vol qua trinh khir oxy hoa tan tao H2O2.<br /> 3.2. Ket qua phan tich COD<br /> Ben canh sir phan tich phi UV-vis, dung dich congo do sau dien phan con dugc dem<br /> phan tich COD de xac dinh do suy giam chi si COD theo thai gian xir ly va su biin thien<br /> hieu suat dong dien khoang boa congo do.<br /> Kit qua xac dinh do suy giam COD dugc bilu dien tren (hinh 4a). Dli vai ca ba truang<br /> hgp sir dung dien cue catot la: C; C/Ppy, C/Ppy(oxit) do suy giam COD dIu tang ddn theo<br /> thai gian dien phan. Ket qua cung cho thdy rdng do suy giam COD trong qua trinh dien phan<br /> dung dich congo do 0,25mM nha hieu ling Fenton dien boa tang len theo trat tu sir dung cac<br /> dien cue catot nhu sau: Dien cue C < C/Ppy < C/Ppy(oxit). Sau 7h xir ly do suy giam COD<br /> dat 180 don vi COD dli vai truang hgp sir dung dien cue catot C; 210 dan vi COD dli vai<br /> truang hgp diing dien cue catot C/Ppy va 240 don vi COD dli vai truang hgp diing dien cue<br /> catot la C/Ppy(oxit). Mot lan nira khdng dinh rdng tai cimg mot thai dilm gia tri dien lugng Q<br /> nhu nhau nhung khi sir dung dien cue catot la C/Ppy(oxit) vai tinh nang xiic tac tit cho qua<br /> trinh khir oxy boa tan tao H2O2 da lam tang tic do cua qua trinh oxy hoa congo do do do lam<br /> cho do suy giam COD cao hon so voi khi sir dung dien cue C va C/Ppy.<br /> <br /> 250 150<br /> <br /> <br /> <br /> <br /> -T-C<br /> - • - C/Ppy<br /> - • - C/Ppy(oxit)<br /> <br /> 4<br /> t(h)<br /> <br /> (a) (b)<br /> Hinh 4: Do suy gidm COD (a) vd hieu sudt ddng (b) trong qud trinh phdn huy congo dd 0,25mMth<br /> thdi gian sir dung dien cue catdt C; C/Ppy; C/Ppy ((exit) vdi mat do dong dp dgt 5mA/cm'<br /> <br /> 106<br />  Hoi nghj Khoa hgc ky niem 35 ndm Vien Khoa hoc vd Cong nghe Viet Nam - Hd Noi 10/2010<br /> <br /> <br /> Ket qua xac dinh hieu suat dong dien khoang hoa congo do dugc bieu dien tren hinh 4b.<br /> Doi voi truang hgp sir dung dien cue C/Ppy(oxit) trong qua trinh dien phan tai nhimg thai<br /> diem ban dau sau Ih dien phan hieu suat dong dat 130% cao ban so voi truang hgp sir dung<br /> dien cue C/Ppy vai hieu suat dong 104% va cao hon nhieu so voi khi sir dung dien cue C voi<br /> hieu suat dong chi 65%. Dieu nay co the ly giai la do co xay ra hieu irng Fenton dien boa nen<br /> CO the xay ra nhieu qua trinh dong thofi nhu; qua trinh oxy boa true tiep congo do tren dien<br /> cue anot, oxy hoa gian tiep congo do tren dien cue catot nha cac tac nhan oxy boa manh gay<br /> ra,... Mat khac cac qua trinh xay ra tren be mat dien cue tao ra cac tac nhan oxy boa manh co<br /> kha nang oxy boa hoan toan congo do va cac hgp chat trung gian dan den hieu suat dong dien<br /> dat gia tn rat cao dac biet dli voi khi sir dung dien cue catot la C/Ppy (oxit).<br /> Theo thai gian ham lugng congo do giam dan dan toi giam hieu suat ciia qua trinh dien<br /> phan doi voi ca ba loai dien cue catot: C; C/Ppy va C/Ppy((oxit).<br /> <br /> <br /> 4. KET LUAN<br /> Da nghien ciin qua trinh khoang hoa Congo do bang phuong phap Fenton dien boa tai mat<br /> do dong 5mA/cm^, sir dung dien cue catot la: C; C/Ppy; C/Ppy((oxit) trong dung dich dien<br /> phan CO mat ion Fe "^, co sue khi oxy. Sau khi xir ly trong 7 gio thu dugc cac ket qua nhu sau:<br /> - Ket qua do UV-Vis cho hieu suat phan buy congo do la 33,85% doi voi dien cue catot<br /> C; 41,26% doi voi dien cue catot C/Ppy va 67,7% doi vol dien cue catot C/Ppy(oxit).<br /> - Ket qua xac dinh COD chi ra rang theo thoi gian dien phan do suy giam COD tang len<br /> doi vai ca ba loai dien cue catot C; C/Ppy; C/Ppy((oxit). Sau 7 gio dien phan chi s i<br /> COD da suy giam tir 300 mg/1 xuong con 60 mg/1 doi voi truang hgp sir dung dien cue<br /> catot C/Ppy(oxit) dam bao dii tieu chuan thai ra moi truang hoac sir dung trong tuoi<br /> tieu, trong trot. Dong thai bieu suat dong dien giam dan trong qua trinh xir ly va dat<br /> gia tri kha cao sau lb xir ly. Dac biet doi voi truong hgp sir dung dien cue catot<br /> C/Ppy(oxit) (130%).<br /> <br /> <br /> TAI LIEU THAM KHAO<br /> 1. D.A. Pozzo, L.D. Palma, C. Merli, E. Petrucci, "An experimental comparison of<br /> graphite electrode and a gas diffision electrode for the cathodic production of<br /> hydrogen peroxide", J. Appl. Electrochem. 35 (2005) 413.<br /> 2. A.A. Gallegos, P. Fletcher, "The removal of low level organics via hydrogen peroxide<br /> formed in the reticulated vitreous carbon cathode cell. Part 1. The electrosynthesis of<br /> hydrogenperoxidein aqueous acidic solution", Electrocbim. Acta 44 (1998) 853.<br /> 3. Z.M. Qiang, J.H. Chang, C.P. Huang, "Electrochemical generation of hydrogen<br /> peroxide from dissolved oxygen in acidic solutions". Water Res. 36 (2002) 85.<br /> 4. Minghua Zhou, Qinghong Yu, Lecheng Lei, Geoff Barton, "Electro-Fenton method<br /> for the removal of methyl red in an eficient electrochemical systeme. Separation and<br /> /'wny/car/o/?", Technology 57 (2007) 380-387.<br /> 5. Nguyen Hong Thai, "Nghien cim tdng hop dien cue mdng composit .tren ca sd polime<br /> ddn dien vd oxit phirc hop nhdm irng dung nhu dien cue xiic tdc dien hda xir ly mdi<br />