Enabling decentralized treatment of BPA through electrified photo-activated advanced oxidation

Abstract

This study explores the integration of electrochemical hydrogen peroxide (H2O2) generation with UVC irradiation as a sustainable strategy for decentralized water treatment. H2O2 was produced in situ using a gas diffusion electrode (GDE) coupled with Ti/IrO2 or boron-doped diamond (BDD) anodes. The metal oxide Ti/IrO2 electrode enabled greater H2O2 accumulation with lower energy consumption due to a lower onset potential for water oxidation. The removal of bisphenol A (BPA) was evaluated under electrochemical oxidation (EO) and UVC-assisted conditions. Treatment with BDD outperformed Ti/IrO2 while achieving complete BPA degradation and up to 46.8% mineralization, the increased oxidation capacity was attributed to the higher generation of reactive radicals on BDD. Radical scavenging experiments revealed that BPA degradation was mainly driven by •OH (~67%), with contributions from SO4•⁻ (~16%). Electron paramagnetic resonance (EPR) experiments were also performed to provide direct evidence of free radical formation, supporting the scavenger results. The process remained effective at environmentally relevant BPA concentrations (<1.0 mg L-1), with energy consumption as low as 3.8 kWh m-3, significantly lower than conventional EO. Degradation pathways involved hydroxylated intermediates and short-chain carboxylic acids, with oxalic and acetic acids persisting after treatment. Matrix constituents markedly affected performance: chloride enhanced removal via active chlorine species, while bicarbonate and natural organic matter suppressed degradation through radical scavenging and light screening. Experiments with tap water confirmed process stability over multiple treatment cycles. These findings demonstrate that photo-assisted EO with in situ H2O2 generation is a highly effective and energy-efficient strategy for BPA removal, with the BDD/GDE/UVC system showing superior performance and scalability potential for advanced water treatment. The system operated without pH adjustment or added catalysts which are key advantages for low-cost and flexible deployment when considering decentralized water treatment systems