The boosted photocatalytic effects of a zeolite supported CdS towards an antibiotic model pollutant: a brief kinetics study.

Abstract

In recent decades, increased world population and industrial activities explosively polluted our environment, especially the aquatic resources. This requires introducing/developing novel methods to decrease the pollution extent of such resources. Here, the hexagonal (wurtzite) CdS nanoparticles (NPs) were synthesized and supported onto ball-mill prepared clinoptilolite NPs (CNP). Samples were briefly characterized by X-ray powder diffraction (XRD), Fourier transform infrared (FTIR), scanning electron microscope equipped with an energy dispersive X-ray analyzer (SEM-EDX), and diffuse reflectance spectroscopy (DRS) techniques. The average crystallite size for CdS NPs and CdS-CNP samples was estimated to be about 9.0nm and 12.3nm (from the Scherrer formula) and about 19.7 and 17.5nm (from the Williamson-Hall model), respectively. From the DRS spectra, the absorption wavelengths of 595 and 546nm correspond to band gap energies of 2.08, and 2.27eV was obtained for CdS NPs and CdS-CNP samples. The samples were then used in the photodegradation of cefotaxime (CT), and the results showed a boosted photocatalytic activity for CdS-CNP rather than CdS NPs. The photodegradation process obeyed the pseudo-first-order kinetic model, and the CdS and CdS-CNP catalysts obtained the k-values of 0.013min-1 and 0.023min-1. When the photodegraded CT solutions were used in COD experiments, the k-values changed to 0.011min-1 and 0.029min-1, respectively. The zeolite support is an eco-friendly natural zeolite with abundant deposits in Iran that yields a cost-effective method.