In situ anchoring strategy to enhance dual nonradical degradation of sulfamethoxazole with high loading manganese doped carbon nitride.

Abstract

A low-cost catalyst with high metal loading and unique catalytic activities is highly desired for peroxymonosulfate (PMS) activation in environmental remediation. Herein, in situ anchoring strategy using 1,10-phenanthroline is reported to construct manganese doped carbon nitride (PMCN) with 8.2wt% manganese loading and dramatically enhanced PMS adsorption and sulfamethoxazole (SMX) removal efficiency. Our study revealed that the PMCN/PMS system readily reacted with contaminants with electron-rich groups, where complete degradation of sulfamethoxazole (SMX) was achieved within 60min. Combining quenching experiments, EPR tests, and electrochemical analysis, we proposed a dual nonradical pathway dominated by high-valent manganese oxygen species (Mn(V)=O) and electron transfer. Systematic investigation elucidated that the introduction of 1,10-phenanthroline constructed denser catalyst active sites, and identified the manganese center and pyridine nitrogen as the active sites for PMS activation. Furthermore, PMCN exhibited excellent pH anti-interference ability and good reusability, achieving more than 90% SMX degradation efficiency after four cycles. This study provides new insights into the regulation of Mn-N active sites and promotes the mechanistic understanding of the synergistic effect of manganese and pyridine nitrogen in PMS activation.