Efficient removal of arsenite by a composite of amino modified silica supported MnO2/Fe-Al hydroxide (SNMFA) prepared from biotite

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 MnO2/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 MnO2 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 pseudosecond-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, oxidationadsorption and electrostatic interaction.

Automated summary

The study developed a novel SNMFA composite using biotite-containing minerals to efficiently remove As(III) from solution. Characterization results showed high removal capacity and confirmed that the adsorption behavior of the composite followed pseudosecond-order kinetic and Langmuir models, being pH and temperature dependent.