The enhanced mechanism of Fe(III)/H2O2 system by N, S-doped mesoporous nanocarbon for the degradation of sulfamethoxazole

Fenton-like technology has been widely used in the field of water treatment as an advanced oxidation processes (AOPs), and a multitude of non-homogeneous catalysts have been reported effectively to enhance it. Herein, nitrogen and sulfur co-doped nanocarbon materials (NSC) was designed and synthesized, which formed a unique mesoporous structure and abundant functional groups on the surface. It exhibits superior catalytic performance to enhance the Fe(III)/H2O2 system for sulfamethoxazole (SMX) degradation, kobs is 18 times higher than Fe(III)/ H2O2 system after the introduction of NSC under the same experimental conditions. Also, the working pH of Fe (III)/H2O2 system was broadened by NSC. Quenching and probe experiments demonstrate that hydroxyl radical (center dot OH) was the dominant active species. Both dissociative and surface-bound iron species were observed, which indicates direct reduction and in-situ binding of Fe(III), respectively. Further investigation found nitrogen and sulfur co-doped attribute to the formation of abundant functional groups, the C-O bond and C-S-C bond on the surface of NSC result in the directly reduce of Fe(III), while -COOH contributes to the in-situ binding. The intermediates and possible degradation pathway of SMX degradation were proposed based on the results of liquid chromatography-quadrupole time of flight-mass spectrometer (LC-QTOF-MS). The results of cycling and co-existing ions experiments demonstrate that NSC has outstanding potential for application. This work provides a novel insight into the sustained removal of micropollutants from the aqueous environment based on the nanocarbon materials enhancing the Fenton-like oxidation.

Automated summary

In this study, nitrogen and sulfur co-doped nanocarbon materials (NSC) were designed and synthesized, which showed superior catalytic performance in enhancing the Fe(III)/H2O2 system for sulfamethoxazole (SMX) degradation. The introduction of NSC increased the kobs by 18 times compared to the Fe(III)/H2O2 system under the same experimental conditions. NSC also expanded the working pH range of the Fe(III)/H2O2 system. The results suggested that the presence of NSC promoted direct reduction and in-situ binding of Fe(III), contributing to the enhanced degradation of SMX.