A new insight into the mechanism in Fe3O4@CuO/PMS system with low oxidant dosage

Developing efficient catalyst for peroxymonosulfate (PMS) activation is of great importance for the degradation and mineralization of organic pollutants. Herein, magnetic Fe3O4@CuOx was constructed to activate PMS for the removal of triclosan (TCS). Our results demonstrated that introducing Fe3O4 not only promoted the dispersion of CuO but also improved the electron donor capacity of Cu and promoted the redox cycle of Fe, thus enhancing effective activation of PMS. Compared with pure Fe3O4 or CuO, the iron-copper interaction of the bimetallic composites facilitated the production of singlet oxygen (1O2), and thus showed excellent adaptability to various inorganic anions and actual wastewater. Of note, O2 may be involved in the reaction to generate superoxide radical (O2•–), which facilitated TCS removal in case of lower PMS dosage (40 μM). Elevating PMS concentration to 500 μM, a theoretical value for 20 μM TCS mineralization, enabled TCS to be deeply mineralized in ultrapure water (86% removal of total organic carbon (TOC)). Further increasing PMS concentration could achieve satisfactory mineralization in wastewater samples with much higher TOC background values. Overall, this study provides a new insight into the mechanism in Fe3O4@CuO/PMS system with low oxidant dosage, which is beneficial to improve the practical application of SR-AOPs.