Developing materials from natural minerals to efficiently remove arsenite (As(Ⅲ)) from solution is vital important for resources comprehensive utilization and environment protection. In this study, biotite containing minerals was used to prepare a novel composite of amino modified silica supported MnO 2 /Fe–Al hydroxide (SNMFA composite), which was then applied to remove arsenite. Scanning electron microscope (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) results indicated that many amorphous MnO 2 and Fe–Al hydroxide nano sheets were loaded on the surface of layered silica structure. Batch experiments showed that this composite could efficiently remove As(Ⅲ) from aqueous solution, and the maximal removal capacity was identified as 46.11 mg/g. As(Ⅲ) adsorption behaviours of SNMFA composite were confirmed by the pseudo-second-order kinetic model and Langmuir model, indicating that As(Ⅲ) adsorption on its surface was monolayer adsorption. The adsorption process was a pH and temperature dependent process, and increasing pH and temperature have facilitated the removal of As(Ⅲ). Thermodynamic analysis showed that As(Ⅲ) adsorption process was a spontaneous endothermic reaction . The As(Ⅲ) removal was mainly relied on the stable inner-sphere coordination model, and the corresponding mechanisms were involved in chelation, precipitation, oxidation-adsorption and electrostatic interaction.
Taking low cost silicate minerals to develop efficient Cd 2+ 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 Cd 2+ . Cd 2+ adsorption behaviors were in accordance of pseudo-second order kinetic model and Langmuir model, and the obtained maximal Cd 2+ adsorption capacity was 78.37 mg/g. Increasing pH and temperature could accelerate the removal of Cd 2+ . The activation energy was calculated as 66.05 kJ/mol, meaning that Cd 2+ 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. Cd 2+ removal mechanisms were consisted of surface complexation and ion exchange between Cd 2+ 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.
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