SYNTHESIS AND PROPERTIES OF MG-ZN-AL-SO4 HYDROTALCITE-LIKE COMPOUNDS

Sulphate-based magnesium-zinc-aluminium synthetic hydrotalcite-like compounds have been prepared by coprecipitation with a sodium hydroxide solution. The corresponding metal solutions were coprecipitated at pH 10, aged in the mother liquor, washed several times and dried at 40-degrees-C. Whatever the ratio of metal ions in the initial metal sulphate solutions, hydrotalcite compounds were formed during coprecipitation. The temperature of preparation and ageing time did not effect the final crystal structure. By comparing the properties of the Mg-Al layered compounds, it seems that when the zinc content increases, the thermal stability of the hydrotalcite-like compounds decreases.