Synthesis of Basic Magnesium Chloride Whisker in MgO-HCl-H2O System at Room Temperature

Abstract

The basic magnesium chloride whiskers were synthesized by using industrial magnesia calcined from magnesite and hydrochloric acid as raw materials. X-ray diffraction, scanning electron microscopy, fourier transform infrared and thermal gravimetric analysis were used to characterize the samples in terms of the composition and morphology. The phase form of 3Mg(OH)₂·MgCl₂·8H₂O (form 318) was confirmed. a possible reaction mechanism and growth mechanism were proposed, the growth units of phase form 318 were amorphous [Mg-(OH)₂] and anion coordination-polyhedra [Mg-(OH)₅]^3- other than [Mg-(OH)₆]^4- octahedra practically existed in system MgO-HCl-H₂O as a precursor, 3Mg(OH)₂·MgCl₂·8H₂O can easily be transformed to Mg(OH)₂ whiskers by base NaOH treatment. This confirmed that the Cl anion was rather than the structure of the free in the basic magnesium chloride whiskers.