Ultrafast Fenton-like reaction using a peroxymonosulfate-mediated confined-Fe0 catalyst for the degradation of sulfamethoxazole

Herein, a nanoconfinement strategy was employed to encapsulate nano zero-valent iron (confined-Fe0) for the rapid degradation of sulfamethoxazole (SMX) through a peroxymonosulfate (PMS)-mediated Fenton-like reaction. The confined-Fe0 catalyst was synthesized in situ using a liquid-phase reduction method, incorporating nitrilotriacetic acid (NA) modified carboxylated carbon nanotube (FOC-N-6). Comprehensive experimental analyses and characterizations demonstrated the FOC-N-6 catalyst facilitated rapid electron transfer through the carbon framework and the surface PMS reactive complex (FOC-N-6-PMS*). This process accelerated the Fe(III)/Fe(II) redox cycle and promoted the formation of surface Fe(II) active sites (Fe0-OCNT-COOFe(II)-), which served as dominant adsorption sites for PMS. Density functional theory (DFT) calculations revealed that the confined-Fe0 structure can decrease the adsorption energy (Eads) of PMS on the FOC-N-6 surface. And the FOC-N-6-PMS* facilitated the rapid degradation of SMX through both non-radical and radical pathways. This confined-Fe0 catalytic strategy holds promise as a viable method for controlling emerging contaminants. [Display omitted] •FOC-N-6 exhibited an extraordinary degradation performance for SMX.•Confined-Fe0 facilitated electron transfer through the OCNT and FOC-N-6-PMS*.•The Fe0-OCNT-COOFe(II)- complex acted as the dominant adsorption site for PMS.•Degradation pathways of direct electron transfer and radical were studied using DFT.•Confined-Fe0 exhibited stability both in catalytic performance and air-exposed storage.