ROLE OF OXYGEN AT THE TiO2 INTERFACE DURING PHOTODEGRADATION OF BIOLOGICALLY DIFFICULT-TO-DEGRADE ANTHRAQUINONE-SULFONATE DYES (original) (raw)

1994, Environmental Toxicology and Chemistry

Heterogeneous photocatalysis via Ti0, suspensions is effective in anthraquinone 2 sulfonic acid sodium salt (ASS) degradation The presence of oxygen promotes the observed semiconductor powder oxidation of the substrate Degradation of ASS in aerated dispersions of Ti0, needed about 24 h at 60°C Added H,O, enhances the degradation rate considerably As the pH increases, the H,02 produced also increases Also, peroxide production was observed as the concentration of Ti0, is increased owing to the availability of more surface states for the reaction The Langmuir adsorption isotherm of ASS on Ti0, Degussa P-25 shows that ASS adsorbs readily on the Ti0, particles The observed rate for H,O, production decreased as the concentration of isopropanol (hole scavenger) is increased, suggesting an oxidative pathway as the main reaction responsible for H,O, photoproduction The degradation of ASS is a result of indirect action due to light mainly absorbed by Ti0, The experiments described here demonstrate the feasibility of dyestuff decomposition via semiconductor powders