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

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.