Avaliação de processos de degradação de corantes dispersos por técnicas eletroquímica e fotoeletroquímica usando eletrodos de Pt, filmes finos e nanotubos de 'TI'/'TIO IND. 2' e bicomponentes 'W'/'WO IND. 3'/'TIO IND. 2'
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Data
2008-06-26
Autores
Osugi, Marly Eiko [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
O comportamento eletroquímico de três corantes dispersos, Vermelho Disperso 1, Laranja Disperso 1 e Vermelho Disperso 13 foi investigado em N,N-dimetilformamida usando tetrafluorborato de tetrabutilamônio como eletrólito de suporte. O grupo nitro dos corantes é reduzido em potenciais de -0,85 V, -0,79 V e -0,69 V, respectivamente, para os corantes Vermelho Disperso 1, Laranja Disperso 1 e Vermelho Disperso 13. A oxidação do grupo amino, também presente nos corantes investigados, ocorre, respectivamente, em potencial de 0,95 V, 0,90 V e 1,0 V e promove a clivagem do grupo azo. Devido à toxicidade e mutagenicidade destes corantes, analisada pelos testes de citotoxicidade em células humanas embrionárias HEK293 e de Ames, respectivamente, investigou-se no presente trabalho novos métodos de degradação dos mesmos em meio aquoso usando o agente dispersante comercial “Emulsogen” por meio de tratamento com cloro ativo (cloração convencional) e fotoeletroquimicamente pela geração de radicais cloro “in situ” sobre eletrodos nanoparticulados de Ti/TiO2, preparados pelo método sol-gel, em NaCl 0,1 mol L-1. A oxidação fotoeletrocatalítica, sobre eletrodos nanoparticulados de Ti/TiO2 em NaCl, mostrou-se mais eficiente quando comparada à cloração convencional, tanto na descoloração que promoveu 100% de remoção de cor, quanto na mineralização dos mesmos (até 60% de remoção de COT). A mutagenicidade dos corantes estudados foi drasticamente reduzida após tratamento fotoeletroquímico. No entanto, a cloração convencional não foi eficiente para total remoção da atividade mutagênica dos corantes, observando-se, ainda, um aumento para o corante Vermelho Disperso 13. A degradação também foi investigada sobre eletrodos de nanotubos de Ti/TiO2, preparados pelo método de anodização eletroquímica...
The electrochemical behavior of three disperse dyes, Disperse Red 1, Disperse Orange 1 and Disperse Red 13, was investigated using N,N-dimethylformamide using in tetrabutylammonium tetrafluoroborate as supporting electrolyte. The nitro group of the dyes is reduced in potential of –0.85 V, 0.79 V and –0.69 V, respectively, for Disperse Red 1, Disperse Orange 1 and Disperse Red 13. The oxidation of amine group, also presents in the dyes molecules, occurs, respectively, at 0.95 V, 0.90 V and 1.0 V and promotes cleavage of azo group. Because of these dyes toxicity and mutagenicity, analyzed by citotoxicity in embryonic human cells HEK293 and mutagenicity detected by Ames test, respectively, new methods of degradation of these dyes in aqueous medium using the commercial dispersant agent “Emulsogen” was investigated by active chlorine treatment (conventional chlorination) and photoelectrochemically by “in situ” chlorine radicals generation using Ti/TiO2 nanoparticulates electrodes, prepared by solgel method, in 0.1 mol L-1 NaCl. The photoelectrocatalytic oxidation, using Ti/TiO2 nanoparticulates electrodes in NaCl presented higher efficiency when compared to conventional chlorination, leading to 100% of color removal and also 60% of mineralization of dyes measured as TOC removal. The mutagenicity of all investigated dyes was dramatically reduced after photoelectrochemical treatment. However, the conventional chlorination was not efficient for mutagenic activity removal of dyes and promoted an increase for Disperse Red 13. The degradation was also investigated using Ti/TiO2 nanotubes electrodes, prepared by electrochemical anodization in fluoride medium and characterized by SEM and photocurrent curves. These electrodes presented 100% of discoloration of all investigated dyes and total organic carbon removal around 70% after 3 hours of photoelectrocatalytic degradation... (Complete abstract click electronic access below)
The electrochemical behavior of three disperse dyes, Disperse Red 1, Disperse Orange 1 and Disperse Red 13, was investigated using N,N-dimethylformamide using in tetrabutylammonium tetrafluoroborate as supporting electrolyte. The nitro group of the dyes is reduced in potential of –0.85 V, 0.79 V and –0.69 V, respectively, for Disperse Red 1, Disperse Orange 1 and Disperse Red 13. The oxidation of amine group, also presents in the dyes molecules, occurs, respectively, at 0.95 V, 0.90 V and 1.0 V and promotes cleavage of azo group. Because of these dyes toxicity and mutagenicity, analyzed by citotoxicity in embryonic human cells HEK293 and mutagenicity detected by Ames test, respectively, new methods of degradation of these dyes in aqueous medium using the commercial dispersant agent “Emulsogen” was investigated by active chlorine treatment (conventional chlorination) and photoelectrochemically by “in situ” chlorine radicals generation using Ti/TiO2 nanoparticulates electrodes, prepared by solgel method, in 0.1 mol L-1 NaCl. The photoelectrocatalytic oxidation, using Ti/TiO2 nanoparticulates electrodes in NaCl presented higher efficiency when compared to conventional chlorination, leading to 100% of color removal and also 60% of mineralization of dyes measured as TOC removal. The mutagenicity of all investigated dyes was dramatically reduced after photoelectrochemical treatment. However, the conventional chlorination was not efficient for mutagenic activity removal of dyes and promoted an increase for Disperse Red 13. The degradation was also investigated using Ti/TiO2 nanotubes electrodes, prepared by electrochemical anodization in fluoride medium and characterized by SEM and photocurrent curves. These electrodes presented 100% of discoloration of all investigated dyes and total organic carbon removal around 70% after 3 hours of photoelectrocatalytic degradation... (Complete abstract click electronic access below)
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Química ambiental, Oxidação fotoeletrocatalítica, Efluentes têxteis - Tratamento, Photoelectrocatalytic degradation
Como citar
OSUGI, Marly Eiko. Avaliação de processos de degradação de corantes dispersos por técnicas eletroquímica e fotoeletroquímica usando eletrodos de Pt, filmes finos e nanotubos de 'TI'/'TIO IND. 2' e bicomponentes 'W'/'WO IND. 3'/'TIO IND. 2'. 2008. 139 f. Tese (doutorado) - Universidade Estadual Paulista, Instituto de Química., 2008.