Sonochemical synthesis of Ag doped zinc sulfide/iron oxide nanocomposites for photocatalytic and magnetic separation applications

The influx of numerous organic contaminants and heavy metals into freshwater sources has serious effects on the aquatic environment and has made life very difficult. Synthesized photocatalysts have demonstrated considerable promise in the degradation of organic pollutants, such as dyes from various sources. This research presents the sonochemical synthesis of Ag doped zinc sulfide/iron oxide nanocomposites as magnetically separable photocatalysts with bifunctional applications. To determine the effect of the weight percentage of dopant on photocatalytic activity, Ag doped zinc sulfide/iron oxide nanocomposites were prepared at different concentrations of dopant, including 2.5, 5, and 10 wt%. Zinc sulfide/iron oxide nanocomposites with and without Ag dopant were employed as photocatalysts for degrading rhodamine B (RhB) as a color pollutant under visible and UV light. In the present study, the photocatalysts were characterized by using x-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM), (energy dispersive x-ray spectroscopy (EDS), Brunauer-EmmetTeller (BET), vibrating sample magnetometer (VSM), fourier transform infrared spectra (FTIR), photoluminescence (PL) spectrophotometry and ultraviolet-visible (UV-Vis) spectrophotometer to survey their structural, morphological, magnetic and optical features. Besides, the Mott-Schottky analysis was utilized to derive the carrier concentrations (ND), flat band potentials of the samples. The results show that doping of Ag in the zinc sulfide/iron oxide nanocomposite led to extended visible light absorption. In addition, approximately 96% of RhB was degraded by 5 wt% Ag doped zinc sulfide/iron oxide nanocomposite after 4hr of visible light irradiation. Moreover, 10 wt% Ag doped zinc sulfide/iron oxide nanocomposite demonstrated a considerable specific surface area (147.7 m2 g-1), which indicates a noteworthy adsorption capacity of 2.74 m g-1. Also, it was demonstrated that the zinc sulfide/iron oxide photocatalyst exhibited a strong magnetic capacity which was revealed by a saturation magnetization (Ms) of 58.22 emu/g, a remanent magnetization (Mr) of 1.4emu/g and a coercivity (Hc) of 11.62 Oe. Eventually, the photocatalytic mechanism of Ag doped zinc sulfide/iron oxide was thoroughly discussed. Therefore, to benefit from the potential of Ag dopants in the preparation of nano composites for wastewater treatment while maximizing the photocatalytic efficiency, a thorough study of their effect on the structural and optical properties of photocatalysts is required.