Synthesis of ZnO/Hydroxyapatite Composite for the Photodegradation of Methylene Blue

Abstract

Methylene blue is a toxic and non-biodegradable cationic dye commonly found in textile wastewater. Photocatalytic degradation using semiconductor materials is an effective approach for its removal. In this study, a ZnO/hydroxyapatite (ZnO/HAp) composite was synthesized via an in situ precipitation method assisted by ultrasonic irradiation, using Zn(NO3)2·6H2O as the precursor and NaOH as the precipitating agent. The synthesized materials were characterized by X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET) surface area analysis, Fourier-transform infrared spectroscopy (FTIR), and ultraviolet–visible diffuse reflectance spectroscopy (UV–vis DRS). The photocatalytic activity of ZnO/HAp was evaluated for methylene blue degradation under UV irradiation at concentrations of 20 and 40 mg/L. The composite exhibited degradation efficiencies of 98.59 and 74.14%, respectively, after 180 min of irradiation. The enhanced performance is attributed to the synergistic interaction between ZnO and HAp, which improves adsorption capacity and facilitates charge separation. These results demonstrate that the ZnO/HAp composite has potential as an efficient photocatalyst for dye removal in wastewater treatment.