Photocatalytic degradation of water contaminants using π-conjugated polymers

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Visible light-induced photocatalytic degradation of iprobenfos pesticide using poly(3-octylthiophene-2,5-diyl) (POTh) film was studied. Addition of FeィイD12+ィエD1 to an aqueous solution of the pesticide and the use of the POTh film blend with sensitizers and/or radical scavengers promoted the degradation of iprobenfos. Active oxygen species formed on the POTh film and degradation mechanism of iprobenfos by the OH radical was also examined. Following results were obtained.1. An aqueous solution of Iprobenhos (10 ppm) was put into a test tube coated with POTh and the solution was irradiated under light of λ>380 nm by varying oxygen pressure of bubbling gas.2. The formation process of the active oxygen species (02・ィイD1-ィエD1 → HィイD22ィエD20ィイD22ィエD2 → OH) was elucidated.3. The acceleration of the degradation by FeィイD12+ィエD1 addition was explained by the increase in the concentration of the OH radical formed via the photo-Fenton reaction.3. Enhancement of the degradation rate and the stabilization of the film was accomplished by blending perylene (sensitizer) and N,N,N',N'-tetramethylbenzidine (cation scavenger) with the POTh film. The result can be explained by energy transfer and/or electron transfer from excited perylene (Per*) to POTh.4. The degradation path which the OH radical attacks on the benzene ring and the side group of iprobenfos was suggested.