Efficient removal of Cd2+ from aqueous solution with a novel composite of silicon supported nano iron/aluminum/magnesium (hydr)oxides prepared from biotite.

Taking low cost silicate minerals to develop efficient Cd2+ adsorption materials was favorable to the comprehensive utilization of minerals and remediation of environmental pollution. In this study, a composite of silicon supported nano iron/aluminum/magnesium (hydr)oxides was prepared with biotite by combining acid leaching and base precipitation process, which was used to remove Cd2+. Cd2+ adsorption behaviors were in accordance of pseudo-second order kinetic model and Langmuir model, and the obtained maximal Cd2+ adsorption capacity was 78.37 mg/g. Increasing pH and temperature could accelerate the removal of Cd2+. The activation energy was calculated as 66.05 kJ/mol, meaning that Cd2+ removal process was mainly depended on chemical adsorption. XRD and SEM results showed that this composite was a micro-nano structure of layered silica supported nano iron/aluminum/magnesium (hydr)oxides. Cd2+ removal mechanisms were consisted of surface complexation and ion exchange between Cd2+ and other metal ions, and the ion exchange interaction played the major role. These results indicated that a novel efficient utilization way for silicate minerals was developed.