Synthesis and Characterization of Hybrid Nanocomposites as Photocatalyst for Wastewater Decontamination

Abstract

In this work, hybrid and bare nanorods of zinc oxide photocatalysts (ZnO, CuS-ZnO, and MoS2-ZnO) are fabricated through a facile microwave-assisted (MW) hydrothermal method as a green preparation process in comparison with the conventional hydrothermal method. The prepared photocatalysts (PCs) are employed under simulated sunlight (SL) for the degradation of various dyes, pharmaceuticals, and pesticides. They are characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), energy-dispersive X-ray spectroscopy (EDX), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV-Vis diffused reflectance spectroscopy as well as photoflourescence. The influence of the preparation conditions on yield, morphological, structural, and optical properties, as well as photocatalytic degradation efficiency, have been investigated. The effect of initial concentration, PC dose, pH at different irradiation times, and their corresponding kinetic of reactions are also studied. The degree of stability and reusability of the prepared ZnO nanorods have been investigated. The influence of matrix effect, salinity, the presence of inorganic ions, and humic acid on the photodegradation efficiency are also studied. It is found that the degradation rate for Methyl Blue (MB) of the sample (ZnO-S2) prepared by the microwave-assisted hydrothermal method is 92% after 60 min exposure, which is 1.5 times higher than that of the sample (ZnO-S1) prepared by the conventional hydrothermal one. Kinetics results described by the pseudo-first-order reaction also confirmed that the degradation rate constant of (ZnO-S2) is 3.5 times higher than that of (ZnO-S1). Also, the results have shown that MW irradiation time has the foremost influence on improving crystallinity, light absorption, and decreasing band gap, as well as enhancing degradation efficiency whereas the precursor ratio has the minor one. It has been confirmed that the hydroxyl and superoxide radicals played the main driving reactive oxidizing role in the photo degradation process. Moreover, it is found that the matrix, salinity, inorganic ions, and Humic acid have a various effects on the degradation activity of PCs.