Photo-electrochemical degradation of some chlorinated organic compounds on n-TiO2 electrode

The electrolysis of some chlorinated organic compounds such as chloroacetic acids, chloromethanes and chloroethenes were carried out on a photo-irradiated n-TiO2 electrode applied a constant potential, 1.0 V vs. Ag/AgCl, and the alternated pulse potentials of +1.0 V and various negative potentials, −1.0, −1.2 and −1.4 V vs. Ag/AgCl in 0.1 mol dm−3 Na2SO4 solutions saturated with oxygen or with nitrogen. These compounds were degraded on the n-TiO2 electrode by the photo-electrolysis and mineralized to carbon dioxide, carbon monoxide and chloride ion. When the alternated pulse potentials were applied, the mineralization yields were increased for these compounds, especially for trichloroacetic acid and carbon tetrachloride, both of which were comparatively stable to the degradation in the constant potential electrolysis.The presence of oxygen in the solution was effective for the mineralization of these compounds, while little effective for that of trichloroacetic acid and of carbon tetrachloride.