Visible light-mediated activation of periodate for bisphenol A degradation in the presence of Fe3+ and gallic acid at neutral pH

Abstract

The current study demonstrates, for the first time, the effectiveness of an innovative visible light (VL) photo-Fenton like system using periodate (PI) mediated by Fe3+ and gallic acid (GA) for bisphenol A (BPA) elimination at neutral pH. The promotion of VL irradiation and GA on the Fe2+/Fe3+ cycle in the system allowed the VL/GA/Fe3+/PI system to exhibit excellent performance for BPA removal. Complete degradation of BPA was carried out in the VL/GA/Fe3+/PI process after 30 min reaction under the optimum conditions (0.10 mM Fe3+, 0.10 mM GA, 1 mM PI, and initial pH 7.0). Electron paramagnetic resonance analysis and quenching tests confirmed that the singlet oxygen, iodate radical, and hydroxyl radical were primarily involved in the elimination of BPA with minor contribution from superoxide anion radical and high-valent iron species (Fe4+ and Fe5+). BPA abatement was slightly inhibited by the addition of Cl−, NO3−, and SO42−, whereas the addition of HCO3− obviously hindered this process. Notably, Huimic acid dramatically expedited BPA decomposition. Besides, the VL/GA/Fe3+/PI process demonstrated remarkable removal efficiency over a broad range of initial pH values (3.01–8.97). Meanwhile, based on the eight identified intermediates, the possible degradation pathways of BPA were predicted. The phytotoxicity test concluded that a decrease in toxicity of the degraded intermediates to the growth of radish seed compared to BPA. In addition, the VL/GA/Fe3+/PI system demonstrated favorable potential for application in different actual water matrices. Moreover, efficient and simultaneous abatement of various organic contaminants by the GA/Fe3+/PI process was success accomplished under natural solar light or VL. Consequently, all results implied that the VL/GA/Fe3+/PI process might be a perspective technique for the treatment of organic contaminants.