Study of the effect of prolonged magnetic stirring on the physico-chemical surface properties of nanometric transition alumina

This article reports the study of a transition nanometric alumina both as such and after prolonged magnetic stirring in bi-distilled water. Stirring was effective in inducing a significant reduction of starting particles agglomeration and modification of the surface properties of the material. The formation of an Al(OH)3 (gibbsite) phase after magnetic stirring in water was detected by means of XRD on powdered samples. Correspondingly, Infra Red spectrum of magnetically stirred alumina outgassed at 150 °C showed a band at ca. 3300 cm−1, ascribable to the hydroxide phase, which decomposes at higher temperature. Differential thermal analysis and thermogravimetry also showed a different thermal behaviour between the two materials, in that magnetically stirred alumina presents a broad endothermic peak at about 280 °C accompanied by an abrupt mass loss (ca. 0.5% of the initial weight), due to dehydration of the hydroxide phase.