Titanium dioxide mediated photocatalysed degradation of phenoxyacetic acid and 2,4,5-trichlorophenoxyacetic acid, in aqueous suspensions

The photocatalysed degradation of phenoxyacetic acid (PAA, 1) and 2,4,5-trichlorophenoxyacetic acid (2,4,5-T, 2), has been investigated in aqueous suspensions of titanium dioxide under a variety of conditions. The degradation was studied by depletion in total organic carbon (TOC) content as a function of irradiation time. The influence of various parameters such as, different types of TiO2 powders, pH, catalyst and substrate concentrations, and in the presence of electron acceptors such as hydrogen peroxide (H2O2) and potassium bromate (KBrO3) besides molecular oxygen have been investigated. The effects of these parameters on the degradation rates were found to be significant. TiO2, Degussa P25 was found to be more efficient for the degradation of both the compounds under investigation as compared with other TiO2 powders. The degradation products were analyzed by GC–MS analysis technique and probable pathways for the formation of different products have been proposed.

Phenoxyacetic acid (PAA) and 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) undergo photomineralization in aqueous suspenstions of TiO2. Figure optionsDownload as PowerPoint slide