Mesoporous ZnAl2O4: an efficient adsorbent for the removal of arsenic from contaminated water

Abstract

We report, for the first time, an efficient soft-templating strategy for the synthesis of mesoporous ZnAl₂O₄ using the supramolecular assembly of lauric acid (surfactant) as a template under alkaline pH conditions. A 50 : 50 (v/v) mixture of water–ethanol has been found to be a very efficient synthesis medium for the dissolution of inorganic precursors, retaining the supramolecular assembly of the lauric acid surfactant and adjusting the necessary pH of the synthesis gel, which are very crucial parameters to obtain the stable mesophase of zinc aluminate. This mesoporous ZnAl₂O₄ material has retained the mesophase upon calcination, showed good BET surface area and electron microscopic results revealed that the material is composed of tiny spherical nanoparticles of dimensions ca. 5–7 nm size. Mesoporous ZnAl₂O₄ showed very good adsorption efficiency for the removal of arsenic from contaminated water. An efficient synthesis strategy, high BET surface area, stable mesophase and good adsorption efficiency for AsO₄³⁻ from arsenic-contaminated water by the mesoporous ZnAl₂O₄ material have huge potential to be explored in the large scale purification of groundwater.