Development of a novel and highly efficient catalyst-free mediated "oxidant-oxidant" process for enhanced decontamination of water contaminants.

Synergistic actions of periodate (PI, IO) and other common oxidants have garnered increasing attention in water treatment. However, previous studies have predominantly focused on single reactive species or been limited by susceptibility to aqueous matrices, thereby posing challenges for broad-spectrum pollutant removal and complex water decontamination. To address this, we proposed an "oxidant-oxidant" strategy that synergistically combined peracetic acid (PAA) with PI for the degradation of micropollutants. Results indicated the PAA/PI system exhibited remarkable efficiency, achieving a 3.4-fold enhancement in sulfamethoxazole (SMX) degradation compared to the HO/PI system. Extensive quenching experiments, probe analyses, and electron spin resonance (ESR) investigations revealed that the dominant reactive species generated in the PAA/PI system were •OH and O. Moreover, O isotope-tracer experiments, combined with theoretical calculations, revealed •OH originated from PI, whereas the O derived from PAA. Due to the synergistic interaction of radical and non-radical pathways, the PAA/PI system possessed excellent resistance to interference, enabling efficient degradation of a wide range of contaminants while maintaining significantly enhanced performance across various real waters. Furthermore, biotoxicity assessments via Escherichia coli growth experiments, Vibrio fischeri toxicology assays, and wheat seed germination tests confirmed that SMX toxicity was substantially reduced following treatment with the PAA/PI system. Additionally, IO was converted into non-toxic iodate (IO) without producing undesired iodine species such as HOI, I, and I. Overall, this study presents a ground-breaking approach for the elimination of micropollutants, offering valuable guidance for the rational design of superior "oxidant-oxidant" systems for water decontamination.