Enhancement of bisphenol A degradation by accelerating the Fe(III)/Fe(II) cycle in graphene oxide modified Fe(III)/peroxymonosulfate system under visible light irradiation.

The photocatalytic behavior of the graphene oxide (GO) modified Fe(III)/peroxymonosulfate (Fe/PMS) system for bisphenol A (BPA) degradation was investigated. With the addition of GO, a dramatic enhancement of BPA degradation was obtained at pH 3.0 under visible light irradiation. According to ESR analysis and quenching tests, both SO and OH are responsible for BPA degradation. The characterization analysis demonstrates that Fe(III) can chelate with the oxygenic functional groups on the surface of GO forming a stable GO-Fe(III) complex. The detections of different kinds of Fe species reveal that Fe(III) can be reduced to Fe(II) by GO via intramolecular electron transfer in the GO-Fe(III) complex, and visible light could enhance this process. The Fe(III)/Fe(II) cycle not only occurs on the surface of GO, but also in aqueous solution via homogeneous reactions. In addition, the degradation pathway of BPA was proposed based on the identification of the intermediates using GC-MS and LC-MS techniques.