FeOOH coupling and nitrogen vacancies functionalized g-C3N4 heterojunction for efficient degradation of antibiotics: Performance evaluation, active species evolution and mechanism insight

In this study, the highly active g-C3N4-based photocatalysts were first constructed by assembling amorphous FeOOH nanoparticles on g-C3N4 nanosheets with nitrogen defects (FeOOH NPs/Nvac-CNNS). Such photocatalysts showed 92.83% and 73.86% degradation and mineralization efficiency of the oxytetracycline hydrochloride (OTC) within 90 min, respectively. Meanwhile, Response Surface Method (RSM) predicted that under optimal conditions (electricity 18.586 A, initial pH 6.371 and dosage 0.6 g/L), OTC degradation efficiency of 94.331% can be achieved. FeOOH NPs/Nvac-CNNS exhibited the excellent reutilization and practical application potential in OTC pollution purification of high and low concentration. The synergistic effect of N vacancies and FeOOH coupling endowed CNNS with advantages, such as the carrier’s fast separation, good visible-light adsorption, H2O2 fast decomposition and excellent molecular oxygen activation. Such advantages greatly contribute to OTC efficient removal in water. Based on the liquid chromatograph-mass spectrometer (LC-MS) analysis, the five possible degradation pathways of OTC were provided. Furthermore, through the quantitative structure-activity relationship (QSAR) analysis, biological toxicity prediction results of OTC and its intermediates indicated that the FeOOH NPs/Nvac-CNNS/vis system had great potential to achieve green and harmless treatment of OTC pollution.