Mechanistic pathways differences between P25-TiO2 and Pt-TiO2 mediated CV photodegradation

The Crystal Violet (CV) dye represented one of the major triphenylmethane dyes used in textile-processing and some other industrial processes. Various metals doped titanium dioxide (TiO2) photocatalysts have been studied intensively for the photodegradation of dye in wastewater treatment. In order to understand the mechanistic detail of the metal dosage on the activities enhancement of the TiO2 based photocatalyst, this study investigated the CV photodegradation reactions under UV light irradiation using a Pt modified TiO2 photocatalyst. The results showed that Pt-TiO2 with 5.8% (W/W) Pt dosage yielded optimum photocatalytic activity. Also the effect of pH value on the CV degradation was well assessed for their product distributions. The degradation products and intermediates were separated and characterized by HPLC-ESI-MS and GC-MS techniques. The results indicated that both the N-de-methylation reaction and the oxidative cleavage reaction of conjugated chromophore structure occurred, but with significantly different intermediates distribution implying that Pt doped TiO2 facilitate different degradation pathways compared to the P25-TiO2 system.