Photo-assisted natural chalcopyrite activated peracetic acid for efficient micropollutant degradation

The effective activation of natural chalcopyrite (CuFeS₂) on peracetic acid (PAA) to remove organic micropollutants was studied under visible light irradiation. Results showed than an effective sulfamethoxazole (SMX) degradation (95.0 %) was achieved under visible light irradiation for 30 min at pH 7.0. Quenching experiments, electron spin resonance analysis, and LC/MS spectrum demonstrated that HO^• and CH₃C(O)OO^• were the main reactive species for SMX degradation, accounting for 43.3 % and 56.7 % of the contributions, respectively. Combined with X-ray photoelectron spectroscopy analysis, the photoelectrons generated on CuFeS₂ activated by visible light enhanced the Fe³⁺/Fe²⁺ and Cu²⁺/Cu⁺ cycles on the surface, thereby activating PAA to generate HO^•/CH₃C(O)OO^•. The removal rate of SMX decreased with the increase in wavelengths, due to the formation of low energy photons at longer wavelengths. Besides, the optimal pH for degradation of SMX by CuFeS₂/PAA/Vis-LED process was neutral, which was attributed to the increasing easily activated anionic form of PAA during the increase in pH and the depletion of Fe species at alkaline conditions. Cl^-, HCO₃^-, and HA slightly inhibited SMX degradation because of reactive species being quenched and/or shielding effect. Furthermore, the degradation efficiency of different pollutants by CuFeS₂/PAA/Vis-LED was also measured, and the removal efficiency was different owing to the selectivity of CH₃C(O)OO^•. Finally, the process exhibited good applicability in real waters. Overall, this study provides new insight into visible light-catalyzed activation of PAA and suggests on further exploration of the intrinsic activation mechanism of PAA.