Non-Radical Activation of Peroxydisulfate by Amine-Functionalized Graphene for Sulfamethoxazole Degradation: Insights into Performance and Mechanism

The activation of persulfate by nonmetallic carbon-based catalysts has emerged as a promising strategy for the efficient degradation of organic contaminants in wastewater. In this study, amine-functionalized graphene (AGR) was synthesized via a facile reduction of graphene oxide (GO) using diethylenetriamine (DETA), which incorporated nitrogen-containing functional groups to enhance catalytic performance. Comprehensive characterization confirmed the partial removal of oxygen-containing groups from GO and the successful incorporation of amine functionalities. The synthesized AGR was employed as a highly effective catalyst for peroxydisulfate (PDS) activation, achieving an impressive 86.3% removal efficiency of sulfamethoxazole (SMX) within 60 min, with a reaction rate constant of 0.029 min^–1. Notably, the catalyst demonstrated excellent recyclability, maintaining consistently high SMX removal efficiency after regeneration. The superior catalytic performance of AGR was primarily attributed to the introduction of amine groups, which facilitated charge redistribution within the graphene framework, thereby promoting efficient electron transfer between SMX and PDS. Electrochemical analyses and reactive species identification revealed that SMX degradation was primarily governed by nonradical mechanisms, including electron transfer and the generation of singlet oxygen (¹O₂). This study provides critical insights into the design of robust carbon-based catalysts with enhanced stability and reduced susceptibility to environmental interferences.