Matrix Effects on the Degradation of Gemfibrozil, Hydrochlorothiazide, and Naproxen by Heterogeneous Photocatalysis

Abstract

The degradation of a pharmaceutical mixture (gemfibrozil, hydrochlorothiazide and naproxen) by TiO 2 /UV-A in different aqueous matrices was evaluated. The matrix components affected the operational conditions, rate constants, and removal efficiency of the pharmaceuticals, as well as toxicity. For sewage treatment plant effluent, a TiO 2 concentration three-fold higher (450 mg L -1 ) and an irradiation time 1.5-3 times longer were required to reach the same efficiency of degradation as the pharmaceuticals in deionized water and surface water matrices. An improvement in the rate constants and the removal efficiency of the pharmaceuticals was achieved by adding 6 mg L -1 of H 2 O 2 and 150 mg L -1 of TiO 2 in deionized water and surface water, but not in the sewage treatment plant effluent, due to the coupling of 450 mg L -1 of TiO 2 and 50-200 mg L -1 of H 2 O 2 . Overall, TiO 2 /UV-A efficiently degraded all compounds, but an additional step is needed for the removal of residual toxicity.