Gallic acid enhanced bisphenol A degradation through Fe3+/peroxymonosulfate process

Fe 2+ is widely used for effective peroxymonosulfate (PMS) activation to eliminate refractory organics. However, Fe 2+ /PMS process suffers from difficulty on Fe 2+ regeneration. Herein, we report an Fe 3+ /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 Fe 3+ /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 (SO 4 •− ), 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 Fe 3+ into Fe 2+ for continuous activation of PMS. The GA boosted Fe 3+ /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 Fe 3+ /Fe 2+ cycling. Gallic acid significantly promoted the Fe 3+ /Fe 2+ cycling. The oxidation performance of Fe 3+ /peroxymonosulfate could be largely elevated by gallic acid. More than 86.4% of BPA could be mineralized by the Fe 3+ /peroxymonosulfate/gallic acid process.