Efficiency and mechanism analysis of bisphenol A degradation by sulfur-doped graphene-catalyzed peroxydisulfate

For peroxydisulfate (PDS) catalysis, although the catalysis performance of sulfur-doped graphene (SG) is recognized, the underlying mechanism remains open for further discussion. In this work, three steps of PDS activation were novelty divided. In step 1, the adsorption and electron-seizing reaction between SG and PDS by confirmed by Fourier transform infrared spectroscopy, electrochemical analysis and density functional theory (DFT). Then (step 2), the dominant C = O and C–S–C functional groups in SG initial for further reactive species generation was identified by Density functional theory calculations. The production of surface-bond complex led to the breakage of O–O bonds to generate highly reactive species which were then analyzed by quenching experiments and electron paramagnetic resonance analysis. The source of ·O2− and 1O2 were determined as S2O82− hydrolysis/dissolved oxygen activation and ·O2− recombination/·O2− hydrolysis. In step 3, BPA-pathway degradation under free-radical and non-radical functions were deduced to confirm the function of reactive species. This work discovered an efficient SG catalyst and deepened the understanding on the mechanism of SG-activated PDS.