Surface-bound radicals-dominated degradation of iopamidol by peroxymonosulfate activated with FeS: Mechanism and application

The activation of peroxymonosulfate (PMS) with FeS is a promising wastewater treatment technology. The degradation mechanism of iopamidol (IPM) in the PMS/FeS system and the effect of Cl − were examined. The results indicated that the surface-bound radicals (SO 4 •− ads and HO • ads ) generated on the FeS surface were identified as the primary reactive species contributing to IPM degradation. The surface and dissolved Fe(II), together with the Fe(II)/Fe(III) cycling facilitated by the surface sulfur on FeS, were all conducive to the activation PMS. When Cl − were in the range of 1 ∼ 5 mmol/L, the IPM degradation rate remained at almost 80 %. The generation of chlorinated products reduces ecotoxicity. The presence of Cl − mitigated the formation of iodoform, notwithstanding the impact on TOC removal. This study can provide a certain basis for the mechanism of FeS/PMS in degrading contaminants and its application for contaminant removal from chlorinated waters.