Sol–gel derived mesoporous GaAlPO4 glass for heavy metal ion sequestration

Abstract

Mesoporous phosphate materials with chemical diversity and a high surface area are essential for their practical applications as heavy metal ion adsorbent materials. Herein, novel gallium aluminum phosphate mesoporous glasses are prepared through a simple aqueous sol–gel route free of any surfactant or template. The glass structure and its evolution from the gel to the final glass were monitored using solid-state NMR techniques, providing detailed insight into the reaction mechanism. During the formation of the mesoporous GaAlPO₄ glass, the gallium entered into the PO₄ tetrahedron via Ga–O–P bonds. The resulting mesoporous glass samples were tested as adsorbents to remove Pb(II) anions from solution and the ternary oxide glasses show high adsorption capacities (>36.63 mg g⁻¹, that is 0.18 mmol g⁻¹). Owing to their integrated features (including their variable compositions, high specific surface area, tunable pore size and shape flexibility) as well as specific acid–base surface properties, such mesoporous gallium aluminum phosphate materials are also expected to have potential either as catalysts or catalyst supports for industrial applications.