Enhanced Photocatalytic Degradation of the Antidepressant Sertraline in Aqueous Solutions by Zinc Oxide Nanoparticles

Abstract

Antidepressants are one of the main pollutants in the aquatic environment. They are being widely studied due to their widespread use, possible health effects, and partial removal from wastewater treatment plants by conventional methods. Photocatalysis is an effective and ecologically beneficial method in wastewater treatment. In the present study, the photocatalytic degradation of sertraline hydrochloride (SERT) in water using nano-sized zinc oxide (ZnO-NPs) was investigated. The ZnO-NPs were synthesized from zinc gluconate as a precursor by the sol–gel method. The crystal structure, morphology, surface charge, and textural properties were characterized by X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray analyses, transmission electron microscopy, Fourier-transform infrared spectroscopy, zeta potential, and N2 adsorption–desorption measurements. The removal of SERT in water was explored by different processes: H2O2/UV, ZnO-NPs/H2O2/UV, and ZnO-NPs/UV. Our results indicate that the combination of both UV illumination and the ZnO-NP as a catalyst was necessary for the efficient degradation of the drug. Nearly complete removal of SERT (98.7%) was achieved in 30 min with the ZnO-NPs/UV process at room temperature. The photodegradation of SERT follows first-order kinetics with a rate constant of 0.0678 min−1. The results reveal that SERT degradation with ZnO-NPs/UV is pH-dependent, as the maximum drug removal was achieved at pH 11. Initial drug concentration, catalyst dose, and hydrogen peroxide concentration were also crucial in the removal of SERT. Our findings indicate that the high specific surface area and porous structure of ZnO-NP enhance its photocatalytic performance toward photodegradation of SERT, i.e., ZnO-NP is an efficient nanophotocatalyst for the degradation of SERT under UV irradiation.