الملخص الإنجليزي
Numerous hazardous organic compounds are introduced into the environment as a result of several man-made activities. Among these organic compounds, the presence of chlorophenols in ground water, surface water and other sources of drinking water has recently become a considerable environmental concern. Due to their stability and bioaccumulation, they remain in the environment for longer periods of time than most other pollutants. Therefore, an effective and economic treatment method for eliminating chlorophenols from water is an urgent demand such as an advanced oxidation process (AOP). In this study, homogeneous cadmium sulfide (CdS) sub-microspheres were successfully prepared via a solution phase and hydrothermal method, using cadmium acetate dihydrate as cadmium source and thiourea as both sulfur source and capping agent. The experimental results demonstrated that the morphology of these CdS crystals can be easily controlled by changing the ratio of cadmium acetate/thiourea. CdS (1:4) samples have homogeneous distribution of nanoparticles compare to 1:2 and 1:3 anion concentrations. CdS@TiO2 core-shell nanostructures were synthesized using as prepared CdS(1:4), via two steps including the solution phase and hydrothermal methods. The prepared CdS@TiO2 core-shell material were characterized by X-ray diffraction (XRD), RAMAN spectroscopy, X-ray photoelectron spectroscopy (XPS), UV-Diffuse Reflectance Spectroscopy (UV-DRS), Scanning Electron Microscopy (SEM), Transmission Electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDX). The SEM analysis revealed that the CdS sub-microspheres prepared by solution phase and hydrothermal methods possess an average size of around 149 and 470 nm respectively. The prepared samples were applied as an photocatalyst for the degradation of 2,4-dichlorophenol and 2,4,6-trichlorophenol under visible irradiation. The results indicated significantly enhanced photocatalytic activity of Cds@TiO2 for degradation of 2,4-DCP and 2,4,6-TCP compared to pure CdS by around 20%. The enhanced photocatalytic performance can be attributed to the longer lifetime of photo-generated electron-hole pairs from the Cds@TiO2 core-shell material, compared to the pure CdS material. The results showed that 70% of 2,4-DCP and 2,4,6-TCP pollutants were degraded in 6 hours under visible light irradiation.
