Unveiling the role of groundwater matrices in electron transfer efficiency of peracetic acid-based advanced oxidation processes

Advanced oxidation processes (AOPs) are pivotal in the degradation of recalcitrant and toxic organic pollutants in water and wastewater. While extensive research has optimized AOPs performance through various experimental parameters, the impact of groundwater matrices on electron transfer processes (ETP) remains inadequately addressed. The mechanism of the ETP is the oxidation of organic complexes and the reduction of peracetic acid catalyst complexes resulting from the co-adsorption of organic compounds and peracetic acid by the catalyst. Therefore, the oxidation potential of sulfamethoxazole and the reduction potential of the AC600/ PAA* complex are affected by the groundwater matrix, which in turn affects the kinetic process of the ETP system. This study investigates the role of groundwater matrices in the AC600/PAA system, revealing how these matrices influence ETP efficiency. We demonstrate that weakly acidic and neutral conditions enhance ETP, while chloride ions (Cl-) facilitate electron transfer and bicarbonate ions (HCO3-) inhibit it. Notably, the presence of humic acid at concentrations below 10 mg/L positively correlates with increased electron transfer rates, indicating robust adaptability to natural organic matter. Contrary to traditional views, our findings highlight that ETP efficiency is significantly improved in real groundwater matrices, suggesting a substantial advantage over conventional radical-based degradation pathways. This research provides critical insights into optimizing AOPs performance in environmental contexts, laying the groundwork for future advancements in electron transfer technology for organic pollutant degradation.