Hollow hydroxyapatite microspheres modified by CdS nanoparticles for efficiently photocatalytic degradation of tetracycline

A novel CdS nanoparticles/hollow hydroxyapatite microsphere (CdS/HAP) photocatalysts, with excellent photocatalytic performance, was firstly prepared by using a facile hydrothermal method under low temperature. The CdS/HAP composite catalysts were explored by various techniques including X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV-vis diffuse reflectance spectroscopy (DRS), X-ray photoelectron spectroscopy (XPS), Brunauer Emmett-Teller (BET) and photoelectrochemical measurements. The photocatalytic ability of the as-prepared composite catalysts was investigated by using tetracycline (TC) as a model contaminant. Compared to pure CdS and HAP, the CdS (10 wt.%)/HAP composite exhibited much higher photocatalytic removal efficiency with 90.2% degradation of TC in 30 min, where the best conditions were an initial pH at 5 and catalyst dosage of 0.50 g/L. Moreover, a probable reaction mechanism of CdS/HAP composite was evaluated based on the analysis of electron spin resonance (ESR) and trapping experiments. It was worth pointing out that the CdS nanoparticles can promote the photo-generated charges separation of HAP microspheres, and thus to improve the photocatalytic degradation performance of the catalysts. It can be inferred that the CdS/HAP composite's photocatalytic superiority could be used for applications in the removal of many hazard pollutants. (C) 2019 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.