Mg3Si4O10(OH)2 and MgFe2O4 in situ grown on diatomite: Highly efficient adsorbents for the removal of Cr(VI)

Diatomite is a kind of nonmetallic mineral that possesses ordered micro- and mesoporous structures, and is well substrate materials for loading highly active oxide nanostructures for the removal of heavy metal ions. In this work, the Mg3Si4O10(OH)(2) and MgFe2O4 nanosheets were loaded on diatomite via a facile hydrothermal method. The Mg3Si4O10(OH)(2)/diatomite sample had a specific surface area of 149 m(2)/g and an extremely large adsorption capacity of 535 mg/g for Cr(VI) adsorption at room temperature, and the MgFe2O4/diatomite sample possessed a higher surface area of 335 m(2)/g and a larger capacity of 570 mg/g for Cr(VI) adsorption under UV light irradiation. The Cr(VI) adsorbed on the surface of MgFe2O4/diatomite was reduced to the less toxic Cr(III). The synergistic effect of between adsorption and photocatalysis might be the main reasons why the MgFe2O4/diatomite sample was superior to the Mg3Si4O10(OH)(2)/diatomite sample in Cr(VI) removal capacity and efficiency. It is assured that such adsorbents have a great potential for practical applications in the removal of heavy metal ions in wastewater.