Degradation mechanism of Bisphenol S via hydrogen peroxide/persulfate activated by sulfidated nanoscale zero valent iron.

Fenton-like oxidation processes are widely used to degrade recalcitrant organic pollutants, but are limited by narrow application pH and low reaction efficiency. This study investigated the synchronous activation of H 2 O 2 and persulfate (PDS) by sulfidated zero valent iron (S-nZVI) in ambient conditions for Fenton-like oxidation of bisphenol S (BPS), an estrogenic endocrine-disrupting chemical. The activation of S-nZVI induced H 2 O 2 or PDS could be greatly enhanced with the assistance of PDS and H 2 O 2 , respectively, even across a wide range of pH value (3-11). The first-order rate constant of S-nZVI/H 2 O 2 /PDS, S-nZVI/PDS and S-nZVI/H 2 O 2 systems was found to be 0.2766 min -1 , 0.0436 min -1 , and 0.0113 min -1 , respectively. A significant synergy between H 2 O 2 and PDS was achieved when the PDS-H 2 O 2 molar ratio was above 1:1, and where sulfidation promoted iron corrosion and decreased solution pH were observed in the S-nZVI/H 2 O 2 /PDS system. Radical scavenging experiments and electron paramagnetic resonance (EPR) investigations suggest that both SO 4 •- and • OH were generated and that • OH played a crucial role in BPS removal. Furthermore, four BPS degradation intermediates were detected and three degradation pathways were proposed in line with the HPLC-Q-TOF-MS analysis. This study demonstrated that compared to the traditional Fenton-like system, the S-nZVI/H 2 O 2 /PDS system could be a more efficient, advanced oxidation technology capable of being used across a broad pH range for emerging pollutants' degradation.