Mg, Al-Hydrotalcite Preparation Based On The Coprecipitation Method

Hydrotalcite is used to designate the lamellar hydroxides with two or more kinds of metallic cations in the main layers which bearing fabric positive charge and interlayer domains containing exchangeable anionic species. As a smoke-free non-toxic halogen-free flame retardants of new varieties, Mg,Al-hydrotalcite is an important part of hydrotalcite family. Its flame-retardant performance was superior to aluminum hydroxide and magnesium hydroxide, and has the strong points of both of them, so Mg,Al-hydrotalcite has broad application prospects. Thus, Mg, Al-hydrotalcite preparation method for industrial production is of great significance.This article studied Mg,Al-hydrotalcite preparation based on the coprecipitation method (include salt-alkali method). Through XRD and SEM analysis of the samples, it is discussed whether the source of magnesium, the source of aluminum and the molar ratio of Mg and Al have an effect on phase composition, particle size and Mg,Al-hydrotalcite surface morphology. Crystallization, high purity and small particle size samples can be made by coprecipitation method with adding surfactants. Then it is analyzed how surfactants influence on the preparation of hydrotalcite in the process and mechanism. Various morphology characterization of Mg, Al-hydrotalcite is made by fractal theory. It is analyzed that the nucleation and growth of Mg, Al-hydrotalcite under different conditions by crystal nucleation theory and the role of surfactants in the process of crystal nucleation.