Performance and mechanism for the removal of rhodamine B by persulfate coupled with sulfidated zerovalent iron

The efficient treatment of dye wastewater is a current research hotspot in the field of water pollution control. In this study, based on the advanced oxidation technology of persulfate (PDS), the reaction system of oxidative degradation of RhB by sulfide-zero-valent iron (S-ZVI)-activated PDS was constructed by sulfide-modification of the interface of zero-valent iron (ZVI) with rhodamine B (RhB) as the target pollutant in dye wastewater. Firstly, the enhanced performance of sulfidation on the PDS/ZVI reaction system was clarified, and the enhancement multiples of the rate constant of the reaction system by sulfidation were 1.1—3.3 in the range of the initial pH of 3.0—9.0. Secondly, the oxidative decolourisation of RhB in water in the PDS/S-ZVI reaction system was confirmed by the quenching experiments, which was mainly achieved by the sulfate radicals. In addition, based on the ferrous release performance of ZVI, the rapid release of ferrous iron from S-ZVI was revealed to be the key mechanism for its activation of PDS potentiation to produce sulfate radicals. Finally, the advantages of PDS/S-ZVI over other oxidation techniques for dye decolourisation were compared, confirming the promising application of the PDS/S-ZVI system for oxidative degradation of dye wastewater.