Mechanistic insights into the degradation of norfloxacin with a S-scheme alignment of bismuth oxychloride/zinc-cobalt layered double hydroxide photocatalysts

Abstract

In this study, BiOCl and ZnCo-LDH were firstly combined to form S-scheme alignment with two-dimensional (2D)/2D structure for norfloxacin (NOR) degradation. The BOC/ZC25 composite possessed the highest photodegradation rate of NOR (94.30 %) under irradiation for 60 min with the reaction rate constant of 0.146 min−1, which was 10.43 and 8.59 times better than that of BiOCl and ZnCo. The S-scheme alignment was confirmed by band gap measurement and the build-in electric field (BIEF) proved by the X-ray photoelectron spectroscopy (XPS). The effects of various factors such as photocatalyst dosage, NOR concentration, pH, and water matrix were also determined to evaluated the practical application activity. The reusability and stability were also studied. ∙O2- has been confirmed as the primary active specie according to the electron paramagnetic resonance (EPR) and capture experiments. Moreover, the degradation mechanism and pathways were also conducted by density functional theory (DFT) calculations and liquid chromatography-mass spectrometer (LC-MS) test. The toxicity assessment of original NOR and its intermediates was measured by Toxicity Estimation Software Tool (T. E. S. T). Therefore, this work designs a novel S-scheme alignment material for efficient antibiotics removal in water treatment.