Synthesis and characterization of MgSO₄·5Mg(OH)₂·2H₂O flake powders

Abstract

Magnesium oxysulfate (MgSO₄·5Mg(OH)₂·2H₂O) flake powders with an average diameter of 2 μm and a thickness of 0.052 μm were prepared using magnesium sulfate and sodium hydroxide as raw materials by hydrothermal synthesis process. The composition, morphology and structural features of the hydrothermal products were examined with X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). The experimental results indicate that in the conditions of n(NaOH)/n(MgSO₄) of 1.25, the dosage of w(Na₃PO₄) crystal additives of 1.0% w(MgSO₄), stirring for 5 h at 180 °C, the morphology of MgSO₄·5Mg(OH)₂·2H₂O products is flaky and laminar, which is a kind of complex magnesium single-crystal. The recycling of MgSO₄ mother liquor was also investigated to make a full use of the materials and reduce disposal. The results prove that there is no adverse effect on the yield and purity of the products.

Keywords

hydrothermal synthesis / magnesium oxysulfate / flake powders / crystal additives

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