Abstract
The aim of this study was to obtain indigenously the mesoporous silica (AMS) precursor to 3-aminopropyltriethoxysilane (APTES) and utilizing chitosan a templating natural biopolymer. The textural characteristics of AMS were obtained by the SEM (Scanning Electron Microscopy) and BET (Brunauer–Emmett–Teller) surface area measurements. AMS solid possessed specific surface area of 511.77m2/g and having pore size and pore volume of 3.38nm and 0.036cm3/g, respectively. Further, the AMS was characterized by the XRD (X-ray Diffraction) and FT-IR (Fourier Transform- Infra Red) analyses. The mesoporous silica was employed for efficient removal of cadmium(II) and lead(II) from aqueous solutions. The influence of solution pH, initial cadmium(II)/or lead(II) concentrations, contact time, and background electrolyte concentrations were studied to deduce the mechanism involved at solid/solution interface. The equilibrium state adsorption data were utilized for the Langmuir and Freundlich adsorption isotherms and the Langmuir adsorption isotherm showed a good agreement with the experimental data. Uptake was found to be fairly fast and the kinetic modelling suggested that the adsorption of cadmium(II)/or lead(II) by AMS was occurred through fractal-like pseudo-second order kinetics. An increase in background electrolyte concentrations from 0.0001 to 0.01mol/L NaNO3 did not affect the removal of lead(II), whereas the cadmium(II) removal was slightly suppressed. The XPS (X-ray Photoelectron Spectroscopy) analysis indicated that removal of cadmium(II) or lead(II) occurred through the formation of a chemical bond with the oxygen atoms present with AMS solid. Furthermore, fixed-bed column adsorption was conducted and the loading capacity of cadmium(II) and lead(II) was found to be 11.54 and 8.59mg/g, respectively.
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