结晶-水热法制备六角片状氢氧化镁

Preparation of hexagonal magnesium hydroxide flake by a crystallization-hydrothermal method

针对常温合成的氢氧化镁(MH)易团聚,分散性差的问题,提出结晶-水热法制备分散性良好的六角片状氢氧化镁,确定了制备MH的最优工艺条件是以12 moL×L^(-1) NaOH为水热矿化剂,7%固含量的MH料浆为前驱体在170 ℃下水热5 h。结果表明制备的MH纯度达99.66%,白度达97.66,比表面积为3.57 m^2×g^(-1),平均一次粒径为0.69μm,颗粒厚度为185nm,(101)面微观应变为2.30×10^(-3),符合一级阻燃型氢氧化镁的标准。水热后的水热矿化剂,可以作为制备MH前驱体的沉淀剂;MH反应得到的NaCl滤液既可作为反应过程的底衬液,又能通过电解生产NaOH,实现了资源的循环利用。

Magnesium hydroxide (MH) synthesized at room temperature tends to agglomerate with poor dispersity. A crystallization-hydrothermal method was proposed in this study to prepare hexagonal magnesium hydroxide flake to solve this problem. The optimum conditions for preparing MH were 12 moL·L^-1 NaOH as hydrothermal mineralizer and 7% MH slurry as precursor at 170 ℃ for 5 h. The results show that MH prepared has high quality with purity = 99.66%, whiteness= 97.66, specific surface area =3.57 m2·g^-1, average primary particle diameter = 0.69 μm, particle thickness = 185 nm and microscopic strain of the (101) plane= 2.30×10^-3, which meets the requirements of the first-grade flame retardant magnesium hydroxide. In addition, the hydrothermal mineralizer of MH can be reused as the reactant for the crystallization of MH precursors, and the NaCl filtrate obtained at the reactive crystallization stage can be reused as the solvent for MH preparation as well as NaOH production by electrolysis, which realizes resource recycling.