Cd2+sorption characteristics of iron coated silica Original Research Article

The present work deals with the Cd2+ sorption studies on iron coated silica synthesized by sol-gel method. The coated media has been characterized before and after the adsorption of cadmium by surface area measurement, scanning electron microscopy (SEM), energy dispersive X-ray (EDX), Fourier transform infrared spectroscopy (FTIR), point of zero charge (PZC) and X-ray diffraction (XRD). X-ray diffraction patterns confirm the amorphous nature of the coated oxide. The uptake of Cd2+ ions is found to increase with increasing concentration, pH and temperature of solution. The Langmuir model is used to interpret sorption of cadmium ions on the solid surface. The values of both ΔH and ΔS are found to be positive, which explains the sorption process to be endothermic and spontaneous in nature. The silica dissolved from the solid surface plays a key role in the in the formation of ligand like surface ternary complexes.