Electro-activation of peroxymonosulfate by a graphene oxide/iron oxide nanoparticle-doped TiO ceramic membrane: mechanism of singlet oxygen generation in the removal of 1,4-dioxane.

Electro-activation of peroxymonosulfate (PMS) has been widely investigated for the degradation of organic pollutants. Herein, we employ graphene oxide (GO)/FeO nanoparticles (NPs) doped into a TiO reactive electrochemical membrane through strong chemical bonding as the cathode to activate PMS for the degradation of 1,4-dioxane (1,4-D). The strong chemical interaction between GO, FeO-NPs, and TiO via Fe-O---GO---O-Ti bonds enhances the electron-transfer efficiency and provides catalytically active sites that boost the electro-activation of PMS. As a result, the 1,4-D oxidation rate of the GO/FeO-NPs@TiO REM cathode is ~3 times higher (7.21 × 10 min) than those of other TiO ceramic membranes, and O plays a key role (59.9%) in the degradation of 1,4-D. The O generation mechanism in the electro-activation process of PMS was systematically investigated, and we claimed that O is mainly generated from the precursors HO and O/HO rather than by O or OH, as has been reported in previous studies. A flow-through mode test in the PMS electro-activation system is firstly reported, and the 1,4-D decay efficiency is 7.1 times higher than that obtained by a flow-by mode, showing that an improved PMS mass transfer efficiency enhances the conversion to reactive oxygen species.