Spherical CdS Nanoparticles Precipitated from a Cadmium Thiosulfate Complex Using Ultraviolet Light for Photocatalytic Dye Degradation

Abstract

Thiosulfate is an inorganic ligand that forms a soluble light-sensitive cadmium thiosulfate complex, and cadmium sulfide (CdS) with a “size effect” can be produced via ultraviolet (UV) irradiation. This study investigated the activity of CdS nanoparticles (NPs) precipitated from a cadmium thiosulfate complex via UV irradiation on photocatalytic dye degeneration. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) demonstrated that the decomposition products were spherical CdS NPs. The photocatalytic activity of the CdS NPs was evaluated based on the degradation rates of methylene blue, rhodamine B, and methyl orange. With 25 mg of CdS NPs and a dye concentration of 10 mg L−1, the degradation rates of the three dyes under visible light were 36%, 90%, and 80%, respectively. A kinetic study revealed that the photocatalytic degradation rate of the CdS NPs followed first-order kinetics, and the rate constants for the three dyes were determined to be 0.0051, 0.0762, and 0.0144 min−1, respectively. The CdS NPs exhibited a stable photocatalytic performance after three cycles of methylene blue degradation. This indicates that CdS NPs formed from a cadmium thiosulfate complex after UV irradiation can be used for photocatalysis, which will save resources and help in environmental conservation.