Gallic acid enhanced bisphenol A degradation through Fe2⁺/peroxymonosulfate process

Fe2⁺is widely used for effective peroxymonosulfate (PMS) activation to eliminate refractory organics. However, Fe2⁺/PMS process suffers from difficulty on Fe2⁺regeneration. Herein, we report an Fe2⁺/PMS process by using gallic acid (GA) as an effective promotor for efficient degradation of bisphenol A (BPA). The process exhibited considerable oxidation performance in the pH range of 3.0-10.0. Higher concentration of Fe2⁺/GA complex exhibited better BPA degradation performance whereby BPA could be completely degraded within 4 mins. Reactive oxidation species (ROS) quenching experiments, electron paramagnetic resonance (EPR) analysis, and methyl phenyl sulfoxide (PMSO) probing experiments revealed that sulfate radical (SO4 -), hydroxyl radical (HO ), and ferryl species are involved and responsible for the BPA degradation. Electrochemical analysis and density function theory (DFT) calculation explored that the self-oxidation of GA boosted the reduction of Fe2⁺into Fe2⁺for continuous activation of PMS. The GA boosted Fe2⁺/PMS system reached an intriguing mineralization efficiency of 86.4%. Findings from this work proposed references to improve the oxidation performance of Fenton-like reaction and provided new sight into the Fe2⁺/Fe2⁺cycling.