The static anion exchange method for generation of high purity aluminium polyoxocations and monodisperse aluminium hydroxidenanoparticles

Abstract

A soft hydrolysis technique involving static anion exchange has been developed in order to prepare extra-pure, hydroxide-free solutions of aluminium polyoxocations (Al₁₃ and Al₃₀) as well as for the preparation of nanosized, highly monodisperse aluminium hydroxide particles in the particle size range 5–150 nm. Quantitative measurements by ²⁷Al NMR, dynamic light scattering, potentiometry (pH and chloride-selective electrode), conductometry and UV–vis spectroscopy (‘Ferron’ kinetic assay) indicate that the static anion exchange method is a very soft, environmentally friendly, low-cost, energy-saving and convenient procedure for the preparation of the mentioned Al-containing systems at fairly high Al concentrations (up to 0.6 mol L⁻¹ in this study). The highly pure solutions of targeted Al species (up to 99% of total Al content) with minimum foreign species including ‘spectator’ ions can be used for high-precision model studies on Al speciation, as well as serving as nanosize precursors to a variety of Al-containing materials.