Waste of printed circuit boards as wet peroxide oxidation catalysts for venlafaxine degradation

• Venlafaxine (VFX) was included in Decision 2022/1307 and Directive 2024/3019. • Waste printed circuit boards (WPCBs) contain recyclable metals such as copper. • WPCBs (e-waste) were used to develop catalysts for wet peroxide oxidation (CWPO). • Catalysts were prepared at various temperatures (400 – 800°C) under N 2 or air. • The VFX micropollutant was successfully degraded in river water and urban wastewater. Waste printed circuit boards (WPCBs), after delamination and recovery of precious metals (gold, platinum), yield a copper-rich residue. This study valorises WPCB residues by developing active and stable heterogeneous catalysts for catalytic wet peroxide oxidation (CWPO). Venlafaxine (VFX), an antidepressant substance frequently detected in surface waters and proposed for its monitoring in quaternary treatment of urban wastewater (Directive (EU) 2024/3019), was selected as a model pollutant. The residue was thermally treated under air (400 or 800°C) or nitrogen (400, 500, or 800°C) to produce the catalysts, which were tested in batch CWPO experiments at natural (6.8) and acidic (2.8) pH. Catalyst selection was based on the best compromise among high VFX removal (and kinetic constant), low residual organic carbon in the treated effluent, and minimal copper leaching. The material treated at 500°C under N₂ atmosphere and tested at natural pH provided the optimal performance, achieving 92% VFX removal within 60 min. This catalyst was further assessed in continuous-flow fixed-bed experiments varying pH, H₂O₂ doses and matrices. Comparable VFX removal efficiencies were observed when VFX was spiked in surface water and urban wastewater. This work demonstrates that WPCB residues are an attractive option to develop catalysts for CWPO.