Removal of Cadmium from Aqueous Solution by Nano Composites of Bentonite/TiO2 and Bentonite/ZnO Using Photocatalysis Adsorption Process

In this study, bentonite/TiO2 and bentonite/ZnO nanoparticles were used for studying the cadmium removal from the aqueous solution. The experiments were done in a batch condition under solar light. The nanoparticles characteristics were determined using analytical devices such as scanning electronic microscopy (SEM), X-ray diffraction (XRD), Transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FTIR) and the N-2 absorption. The optimum condition of the adsorption process was obtained at an initial concentration of 6 ppm, time of 6 h, 45 degrees C temperature, 4 g/L bentonite/ZnO (pH = 5) and 2 g/L for bentonite/TiO2 (pH = 7). Also, the cadmium removal increased for bentonite/TiO2 adsorbent with increasing the light intensity but it had no effect on the bentonite/ZnO adsorbent. In this work, the adsorption isotherm and kinetics were investigated and results showed that the adsorption process followed better by Temkin isotherm and the adsorption kinetics better described by the pseudo-second-order model.