Advanced oxidative degradation of sulfamethoxazole by using bowl-like FeCuS@Cu2S@Fe0 catalyst to efficiently activate peroxymonosulfate

A novel hierarchical bowl-like FeCuS@Cu2S@Fe0 nanohybrid catalyst (B-FeCuS@Cu2S@Fe0) was synthesized for removing sulfamethoxazole (SMX) through catalytic activation of peroxymonosulfate (PMS). It was found that this catalyst exhibited excellently high catalytic activity. Under optimized reaction conditions, all the added SMX (12 mg/L) could be completely degraded within 5 min. The SMX degradation followed pseudo first order kinetics with a rate constant k of 0.89 min-1, being 1.38, 4.51, 8.99 and 35.6 times greater than that of other catalysts including Fe0 (0.644 min-1 in the very initial stage), bowl-like iron-doped CuS (B-FeCuS, 0.197 min-1), bowl-like CuS (B-CuS, 0.099 min-1) and Cu2O (0.025 min-1), respectively. During the degradation, several reactive oxygen species (·OH, SO4·- and 1O2) were generated with ·OH as the main one as confirmed by electron paramagnetic resonance analysis. The SMX degradation in the present system included both radical and non-radical mediated processes. A possible mechanistic insight of the PMS activation by bowl Fe0 decorated CuS@Cu2S-based catalyst was proposed according to X-ray photoelectron spectroscopic (XPS) analysis, and the degradation pathway of SMX was speculated by monitoring the degradation intermediates with liquid chromatography coupled with mass spectrometry (LC-MS).