Bio-electro-Fenton (BEF) technology has shown significant advantages in the treatment of antibiotic wastewater. However, the strict pH application range (2-3) still limits the practical application of BEF. To overcome the limitation of pH on traditional BEF, CoFe-LDH/g-C3N4 composite catalyst was synthesized by hydrothermal method and applied to the BEF cathode to construct a photo-BEF (PBEF) system. The performance of the PBEF system under visible light was investigated with tetracycline hydrochloride (TC) as the target pollutant. The results showed that the PBEF system could extend the pH application range to 3-11 and could maintain more than 80 % of TC removal. The highest removal efficiency of TC by PBEF reached 94.98 % at pH 5, and the highest TOC removal could achieve 70.09 %, indicating that the PBEF can effectively remove TC. Meanwhile, PBEF also showed good universality, anti-interference and stability. In addition, to explore the mechanism of TC degradation by PBEF, the quenching experiments and electron spin resonance (ESR) tests were used to identify and evaluate the contribution of the reactive oxygen species in TC removal. And the results showed that e- and •OH played the major role in TC removal. Density functional theory (DFT) calculations were used to analyze the active sites of TC molecules, and three possible degradation pathways of TC were proposed. Moreover, the toxicity of TC degradation by PBEF was effectively reduced. This study proposes a new way to broaden the application range of pH by PBEF and provides a novel alternative for antibiotics removal from wastewater.
Keywords: CoFe-LDH/g-C(3)N(4); Heterogeneous photo-bio-electro-fenton; Performance and mechanism; Tetracycline; Wide pH range.
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