Synthesis and characterization of direct Z-scheme CdS/TiO2 nanocatalyst and evaluate its photodegradation efficiency in wastewater treatment systems

In the present research, the photocatalytic degradation of dimethyl sulfoxide (DMSO), a reference substance for determination of photocatalytic efficiency of wastewater treatment systems, in the presence of CdS/TiO2 nanoparticles under visible light irradiation was investigated. For this purpose, an ultrasonic method combined by microemulsion was used to synthesize CdS/TiO2 core/shell nanoparticles in a mild condition without surfactant. The morphology, structure and properties of the nanoparticles were studied via X-ray diffraction (XRD), transmission electron microscopy (TEM), ultraviolet-visible spectra (UV-vis), Fourier transform near IR (FTIR), energy-dispersive X-ray (EDAX) and dynamic light scattering (DLS). The TEM image clearly indicated the size of non-agglomerated nanoparticles in the absence of surfactant, are almost 10 nm in a spherical shape. UV-vis spectra for these particles revealed a red shift in absorption edge up to 570 nm which was in green area. The photodegradation studies were performed in a batch photoreactor with a sun simulator lamp. The degradation efficiency of nanoparticles was investigated by high-performance liquid chromatography (HPLC) device and high degradation efficiency up to 80% was recognized with this method. Also, kinetic study of photodegradation of nanoparticles was performed in an arbitrary point and the rate of DMSO degradation was fitted to Langmuir-Hinshelwood kinetic model and consequently, K parameter, has been determined.