Synthesis of magnesium hydroxide and its calcinates by a precipitation method with the use of magnesium sulfate and poly(ethylene glycols)

The effect of type and concentration of modifiers on the physicochemical and functional properties of magnesium hydroxide obtained by precipitation, and its calcinate magnesium oxide, was studied. Magnesium hydroxide obtained from magnesium sulfate and sodium hydroxide was subjected to thermal decomposition at 450 °C. The precipitation reaction took place in optimised conditions with the use of a modifier at suitably chosen concentration and molecular mass. The modifiers were non-ionic compounds representing poly(ethylene glycols): PEG 200, 8000, 20 000. Detailed and comprehensive characterisation of the unmodified and modified samples, either hydrated or calcined was made. The magnesium hydroxide samples obtained in this study show plate morphology of particles. The modifier introduced into the reaction system had a direct influence on the morphological and dispersive properties of the products as well as their surface character and specific surface area. However, it was proved that the presence of a modifier did not change the crystalline structure of the products. A mechanism of PEG activity explaining the effect of different concentrations of the modifier on agglomerate formation was proposed.

The influence of PEG modifiers on unique physicochemical properties of magnesium hydroxide obtained by precipitation was presented. Magnesium hydroxide obtained from magnesium sulphate and sodium hydroxide was subjected to thermal decomposition at 450 °C. The synthesised samples of magnesium hydroxide and magnesium oxide have the crystalline structures of brucite and periclase, respectively. Dielectric study of MgO modified with PEG exhibits insulating properties.Figure optionsDownload as PowerPoint slideHighlights
► Application of poly(ethylene glycols) in synthesis of Mg(OH)2 and MgO.
► Mechanism of the adsorption modes of PEG on the Mg(OH)2 nanoplates surfaces.
► The influence of modifiers on Mg(OH)2 and MgO dispersive properties.
► The effect of PEGs on the MgO dielectric properties.