Heterogeneous sulfite-based advanced oxidation process is extremely promising for the removal of various industrial pollutants owing to its generation of multiple reactive oxygen species (ROS), while the unclear mechanism of S(IV) conversion and ROS generation hinder its practical applications. Here, the iron-copper bimetallic was synthesized for potassium pyrosulfate catalysis, which was designed for insight into the mechanism of micropollutant degradation driven by sulfur species conversion. Experimental and theoretical calculations have shown that the reaction process and corresponding mechanisms can be significantly distinguished into three different stages. Stage one prepares sufficient Fe(III) for the initiation of the reaction, while stage two generating ROS and reduces S(IV). In the stage three, the low-valent sulfur produced from S(IV) combines with iron-copper materials to form highly active sulfur sites, which react with O2 to generate a large number of hydroxyl radicals (•OH). Furthermore, a variety of contaminants were used to validate the universality of the system, and their wide distribution in wastewater implies broad application prospects. This research provides in-depth interpretations of the induced mechanism of sulfur species conversion in the sulfite heterogeneous system, provides a solid theoretical foundation for the engineering application of the system.
Keywords: Heterogeneous sulfite system; Hydroxyl radicals; Iron-copper bimetal; Potassium pyrosulfate; Sulfur species.
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