Photocatalysis enhancement and Cl− boosting mechanisms of peracetic acid-based advanced oxidation processes for antibiotic removal by using HOF-Cu-g-C3N4

Abstract

In recent years, the utilization of the peracetic acid (PAA)-based advanced oxidation process (AOP) for water treatment has gained significant attention. This is due to its ability to generate highly reactive species such as hydroxyl radicals (˙OH) and organic oxygen radicals (R-O˙), which efficiently degrade organic pollutants in water. However, traditional activation methods involving ultraviolet radiation, heat, and transition metal ions have limitations in terms of efficiency, control, and potential metal sludge production. To address these challenges, a novel heterogeneous PAA-based AOP process utilizing the HOF-Cu-g-C₃N₄ catalyst was developed for high-performance antibiotic removal. This approach effectively coordinates the reaction interfaces, activation sites, and light energy harvesting for enhanced activity and sustainability. X-ray photoelectron spectroscopy (XPS) analysis of HOF-Cu-g-C₃N₄ indicated that heterogeneous catalysis occurred at two different active sites on the catalyst's surface. The analysis also revealed that the presence of hydroxyl radicals (˙OH) and organic radicals (such as CH₃C(O)O˙ and CH₃C(O)OO˙) played a significant role in the generation of free radicals in the PAA system. These free radicals were found to dominate the oxidative degradation of antibiotics. The degradation of antibiotics was observed to be effective over a wide pH range, especially at near-neutral pH. Interestingly, the addition of Cl⁻ ions was found to have a notable promotion effect on the degradation of antibiotics. The electrochemical characterization results and free radical measurement provided evidence for the most plausible free radical mechanism and the Cl⁻ ion boosting mechanism. These findings highlight the environmental applicability and versatility of the HOF-Cu-g-C₃N₄ catalyst for the advanced treatment of refractory pollutants.