Preparation and drying kinetics of magnesium hydroxide nanoparticles

Magnesium hydroxide is a kind of inorganic flame retardant with triple function of filling, flame retardant and smoke suppressant, which can be used for flame retardant of many kinds of polymers. Besides, magnesium hydroxide can also be used in environmental protection, such as flue gas desulfurization, treatment of lead-containing wastewater and wastewater deammonium and phosphorus removal, etc. It is also used in food additives, oil additives and biological and pharmaceutical preparations to varying degrees and is a kind of green chemical product recognized as friendly to the environment. With the development of nanotechnology, the preparation of nano-magnesium hydroxide has gradually become one of the current research hotspots. As a necessary step in the preparation of high-quality magnesium hydroxide nanoparticles by liquid-phase chemical method, drying has a direct impact on the quality of the products.

The monodisperse magnesium hydroxide nanoparticles were prepared by liquid phase precipitation method using magnesium chloride hexahydrate and alkaline precipitant as raw materials. The optimum conditions for the synthesis of monodisperse magnesium hydroxide nanoparticles were determined by single-factor experiments: ethanol/water (80/20, v/v) as the reaction solvent; sodium hydroxide as the precipitant was added directly to the magnesium chloride solution; the initial concentration of magnesium chloride was 0.1 mol/L. Magnesium hydroxide nanorods and magnesium hydroxide nanosheets were prepared by the precipitation transformation method using magnesium chloride hexahydrate, light magnesium oxide and urea as raw materials. nanorods and magnesium hydroxide nanosheets were prepared by precipitation transformation method. The drying kinetics of the monodisperse magnesium hydroxide nanoparticles, magnesium hydroxide nanorods and magnesium hydroxide nanosheets were investigated by drying experiments.

The results showed that the drying curves and drying rate curves of the three different morphologies of magnesium hydroxide nanoparticles, magnesium hydroxide nanorods and magnesium hydroxide nanosheets were similar in shape; the Logarithmic model was chosen as the thin-layer drying model to describe the drying curves of magnesium hydroxide nanoparticles, magnesium hydroxide nanorods and magnesium hydroxide nanosheets, respectively.