Catalytic and Photocatalytic Oxidation of Aqueous Bisphenol A Solutions: Removal, Toxicity, and Estrogenicity

Catalytic wet-air oxidation (CWAO) of aqueous solutions of bisphenol A (BPA) was investigated in a trickle-bed reactor at temperatures up to 230 degrees C and oxygen partial pressure of 10.0 bar over TiO2 and Ru/TiO2 solids. It was observed that in the given range of operating conditions BPA undergoes both noncatalyzed and catalyzed oxidation routes. The employed Ru/TiO2 catalyst containing 3.0 wt % of metallic phase enabled complete removal of BPA and more than 96% of TOC removal at temperatures of 200 degrees C and above. No catalyst deactivation occurred that could be attributed to the dissolution of active ingredient material. At these conditions, no carbonaceous deposits were accumulated on the catalyst surface. The acute toxicity of end-product solution:: to organisms from different taxonomic groups and estrogenicity determined by the genetically modified yeast, compared with those of the feed solutions, was significantly reduced by CWAO treatment over the Ru/TiO2 catalyst. For comparison, oxidative destruction of BPA was also investigated in this study by means of either photolytic or heterogeneous photocatalytic oxidation. A commercial TiO2 photocatalyst illuminated by UV light enabled complete removal of BPA; however, lower decrease of toxicity and estrogenicity in the treated solution was observed.