Photocatalytic decomposition of cortisone acetate in aqueous solution.

•Most efficient photocatalysts for cortisone 21-acetate (CA) degradation were ZnO and TiO2 (P25).•The decomposition rate increased at low CA concentrations.•No pH dependence was observed allowing CA photocatalytic degradation at native pH.•Synergistic CA degradation effects between TiO2 and S2O82− were found.•LC–MS confirmed a decrease in CA concentration, but no intermediate products were detected.