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

Abstract

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 Fe3+/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 Fe3+/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 Fe3+ into Fe2+ for continuous activation of PMS. The GA boosted Fe3+/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 Fe3+/Fe2+ cycling. HIGHLIGHTS Gallic acid significantly promoted the Fe3+/Fe2+ cycling.; The oxidation performance of Fe3+/peroxymonosulfate could be largely elevated by gallic acid.; More than 86.4% of BPA could be mineralized by the Fe3+/peroxymonosulfate/gallic acid process.;

Keywords

• activation
• degradation
• fe2+
• ferryl species
• peroxymonosulfate