The pivotal role of pH in controlling the Fe3S4/PMS system for sulfamethazine removal: From adsorption to non-radical oxidation

s In this study, Fe 3 S 4 was synthesized by hydrothermal method for the activation of peroxymonosulfate (PMS) to degrade sulfamethazine (SMT). The mechanism of pH influence on the degradation process was systematically investigated, revealing that neutral conditions (pH = 7) yielded the highest degradation efficiency, achieving 99% SMT removal within 30 min. Experimental analysis indicates that the Fe S synergistic effect in Fe 3 S 4 efficiently activates PMS, with singlet oxygen ( 1 O 2 ) serving as the primary active species, indicating that the degradation proceeds predominantly via a non-radical pathway, with minor contributions from radicals such as SO 4 •− and • OH. This system maintained excellent degradation performance in actual water bodies containing various coexisting anions and exhibited broad-spectrum removal capabilities for multiple pollutants. Fe 3 S 4 retained over 80% activity after five cycles, demonstrating good stability and application potential. Overall, this study provides an efficient, stable, and multifunctional catalyst for advanced oxidation processes based on PMS, offering broad application prospects in environmental remediation and water treatment.