Electro-peroxone treatment of the antidepressant venlafaxine: Operational parameters and mechanism

Highlights: • E-peroxone is a novel electrocatalytic ozonation process that couples ozonation with electrolysis to enhance pollutant decay. • Carbon-based cathodes are used to electrocatalytically produce H₂O₂ from O₂ in sparged O₂ and O₃ mixture. • The in-situ generated H₂O₂ reacts with O₃ to yield ·OH for pollutant mineralization. • Venlafaxine is mineralized much faster by E-peroxone than by ozonation and electrolysis. - Abstract: Degradation of the antidepressant venlafaxine by a novel electrocatalytic ozonation process, electro-peroxone (E-peroxone), was studied. The E-peroxone treatment involves sparging ozone generator effluent (O₂ and O₃ gas mixture) into an electrolysis reactor that is equipped with a carbon-polytetrafluoroethylene cathode to electrocatalytically transform O₂ in the bubbled gas to H₂O₂. The in-situ generate H₂O₂ then reacts with the bubbled O₃ to yield ·OH, which can non-selectively degrade organic compounds rapidly in the solution. Thanks to the significant ·OH production, the E-peroxone treatment greatly enhanced both venlafaxine degradation and total organic carbon (TOC) removal as compared to ozonation and electrolysis alone. Under optimal reaction conditions, complete venlafaxine degradation and TOC elimination could be achieved within 3 and 120 min of E-peroxone process, respectively. Based on the by-products (e.g., hydroxylated venlafaxine, phenolics, and carboxylic acids) identified by UPLC–UV and UPLC/Q-TOF-mass spectrometry, plausible reaction pathways were proposed for venlafaxine mineralization by the E-peroxone process. The results of this study suggest that the E-peroxone treatment may provide a promising way to treat venlafaxine contaminated water.