Photocatalytic activation of peroxydisulfate by a new porous g-C3N4/reduced graphene oxide/TiO2 nanobelts composite for efficient degradation of 17α-ethinylestradiol

Abstract

A new porous C3N4/reduced graphene oxide/TiO2 nanobelt catalyst (CRT) was assembled and used to remove 17α-ethinylestradiol (EE2) in the presence of peroxydisulfate (PS) and visible light. The characterization results showed that larger porous graphite carbon nitrides (pg-C3N4) covered onto the surface of TiO2/reduced graphene oxide (RGO), in which layered RGO was wrapped onto the surface of anatase TiO2 nanobelt uniformly. The layered RGO in CRT played significant role in separation of electron-hole pairs and nonradical activation. The electron paramagnetic resonance and quenching experiment revealed that h+, 1O2 and •O2– and direct electron transfer route contributed to complete removal of 6 mg/L EE2 within 6 min only with 0.5 g/L dosage and 1 mM PS. The degradation rate of EE2 in CRT/PS/Vis was 207.51 times than that in photocatalysis. The degradation products were identified by a solid phase extraction pretreatment method combined with ultra-high-performance liquid chromatography-mass spectrometry, and possible degradation pathways were proposed. Moreover, the estrogenic activities can be rapidly eliminated in CRT/PS/Vis process.