A Strategy for Enhancing Tetracycline Degradation Under Low-Energy Visible Light Radiation: Synergistic Effect of Z-Heterojunction G-C3n5/Biocl and Persulfate Electron Capture

Abstract

A novel heterojunction g-C3N5/BiOCl was constructed in situ using a simple solvothermal method, and combined with persulfate (PDS) to degrade tetracycline under low-energy visible light irradiation. After 90 minutes of irradiation with 80W LED light, the TC removal rate reached over 92%, and the optimal operating parameters for g-C3N5/BiOCl dose, PDS dose, and pH were 0.3 g/L, 2 mM, and 9, respectively. The photocatalytic mechanism was elucidated by UV-vis differential reflectance spectroscopy (DRS), photoluminescence (PL) spectroscopy and active species capture test. The results indicated that the Z-type heterojunction decreased the band gap of g-C3N5/BiOCl and accelerated the separation and transfer of photo generated carriers at the heterojunction interface; Simultaneously, the synergistic electron grazing effect of S-O bond in PDS effectively prevented the complexation of electron-hole pairs (e--h+), facilitating the formation of ·O2- and h+. Then, the intermediate of TC degradation was analyzed by HPLC/MS, and demethylation and benzene ring cleavage were identified as main steps. In addition, g-C3N5/BiOCl had good activity and stability after five cycles, proving its engineering application prospects.

Keywords: Visible Light, g-C3N5/BiOCl, persulfate, Tetracycline, Low-energy input