Photoinduced and electrochemical induced degradation of the 4th EU watchlist compound venlafaxine

Abstract The European Union require environmental monitoring of the antidepressant drug venlafaxine. Advanced oxidation processes provide a remedy against spread of micropollutants. In this study, the photoinduced and electrochemical decompositions of venlafaxine were investigated in terms of mechanism and efficacy using high-performance liquid chromatography coupled to high-resolution multifragmentation mass spectrometry. Kinetic analysis, structure elucidation, matrix variation and radical scavenging indicated the dominance of a hydroxyl mediated indirect mechanism during photo-degradation, hydroxyl and direct electrochemical oxidation for electrochemical degradation. Oxidants, sulfate and chloride ions acted as accelerants. Humic acid decelerated degradation during UV irradiation, but accelerated during electrochemical oxidation. In silico QSAR analysis predicted decreased environmental hazard after AOP treatment. In general, photo-irradiation proved more efficient due to faster decomposition and slightly less toxic transformation products. Yet, matrix effects would have to be carefully evaluated when potential applications as a fourth purification stage were to be considered.