Interfacial charge transfer in coal gangue/NiO-x composites photocatalyst for efficient-degradation of ciprofloxacin

Coal gangue (CG) is a kind of widespread industrial waste, its large accumulation brings great challenges to the environment. Thus researchers has been widely concerned the efficient utilization of CG. At the same time, fluoroquinolone antibiotics contaminants, such as ciprofloxacin (CIP), are difficult to degrade, have low environmental capacity and wide migration range, and have constantly detected in various kinds of water bodies, and are a kind of toxic organic pollutant. In this study, the CG/NiO-3 composite catalyst was synthesized by chemical precipitation combined with high temperature pyrolysis. Under the conditions of 20.0 mg·L−1 CIP concentration, 0.4g·L−1 catalyst dosage and initial pH = 7.0, 180 min of sunlight was simulated, and the removal efficiency reached 87.48%. Through scanning electron microscopy (SEM), X-ray diffraction (XRD), fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), nitrogen adsorption-desorption, electron paramagnetic resonance (EPR), found that the degradation efficiency of CG/NiO-3 composites catalyst is improved because the hydroxyl group on the surface of CG promotes the generation of free radicals through the adsorption of oxygen and the introduction of CG increases the specific surface area. It provides more active sites while promoting the interfacial charge transfer and increasing the absorption of sunlight. Therefore, this work provides reference significance and theoretical basis for the resource utilization of CG and the treatment of organic pollutants.