Mechanism for catalytic ozonation of p-nitrophenol in water with titanate nanotube supported manganese oxide

Abstract

Manganese oxide supported on titanate nanotubes (TNT) was prepared by an impregnation method and used as a catalyst for ozonation of p-nitrophenol (PNP) in an aqueous solution. Characterization results indicated that the manganese oxide was highly dispersed on the surface of TNT. The synthesized catalyst exhibited high activity for the mineralization of PNP with ozone, and about 95% of the total organic carbon was removed at 45 min. The degradation of PNP was mainly due to the oxidative process in solution, and the hydroxyl radical reaction played an important role for the degradation of its ozonation products (formic acid and oxalic acid). The negatively charged surface and surface acid sites of the support favored the adsorption of ozone, while the highly dispersed MnO_x accelerated the decomposition of adsorbed ozone into hydroxyl radicals. A possible mechanism for the catalytic ozonation of PNP was proposed.