Enhanced degradation of organic contaminants in water by peroxydisulfate coupled with bisulfite.

In this study, the bisulfite-peroxydisulfate system (S(IV)/PDS) widely used in polymerization was innovatively applied for organic contaminants degradation in water. The addition of S(IV) into PDS system remarkably enhanced the degradation efficiency of bisphenol A (BPA, a frequently detected endocrine disrupting chemical in the environments) from 17.0% to 84.7% within 360 min. The degradation efficiency of BPA in the S(IV)/PDS system followed pseudo-first-order kinetics, with rate constant values ranging from 0.00005min-1 to 0.02717min-1 depending on the operating parameters, such as the initial S(IV) and PDS dosage, solution pH, reaction temperature, chloride and water type. Furthermore, nitrogen purging experiment, radical scavenging experiment and electron spin resonance (ESR) analysis were used to elucidate the possible mechanism. The results revealed that sulfate radical was the dominant reactive species in the S(IV)/PDS system. Finally, based on the results of liquid chromatography-mass spectrometry (LC-MS) and gas chromatography-mass spectrometry (GC-MS), the BPA degradation pathway was proposed to involve β-scission (CC), hydroxylation, dehydration, oxidative skeletal rearrangement, and ring opening. This study helps to characterize the combination of PDS and inorganic S(IV), a common industrial contaminant, to generate reactive species to enhance organic contaminants degradation in water.