Photocatalytic activation of persulfate for rapid degradation of 17α-ethinylestradiol over quasi-full-visible-responsive Pg-C3N4/RGO/BiOI

The photocatalytic activation of persulfate is an effective and environmentally friendly method to eliminate emerging contaminants (ECs). However, the composition and structure of a catalyst is the key for its photocatalytic activation performance. Herein, we assembled porous C3N4/reduced graphene oxide/BiOI nanosheet catalyst (denoted as CRB) to activate peroxydisulfate (PS) for the degradation of 17α-ethinylestradiol (EE2), sulfamethoxazole (SMX) and bisphenol A (BPA). The assembling method and preparation conditions of CRB were optimized, and the effect of degradation conditions were investigated. The result showed that CRB possessed quasi-full-visible response (779 nm), superior carrier separation and high PS utilization efficiency. More importantly, only 0.25 g/L CRB and 0.5 mM PS were needed to completely degrade 6 mg/L EE2 within 2 min under visible light illumination. The electron paramagnetic resonance and active species trapping experiments showed the main reactive species were singlet oxygen (1O2), h+ and O2•-. The possible degradation pathways of EE2 were proposed based on intermediates confirmed by ultra-high-performance liquid chromatography-mass spectrometry. Moreover, the estrogenic activity of intermediates was eliminated using estrogen-sensitive MCF-7 cell method. It is an effective photocatalytic activation system of PS to degrade electron-rich ECs.