Potential one-pot synthesis of spherical magnesium silicate powder by mechanical milling

Synthetic magnesium silicate finds applications in adsorbents, catalysis, pharmaceuticals, foods, cosmetics, and in oil industry. This study introduces a method for potential one-pot preparation of narrowly sized, spherical magnesium silicate powders. After initial synthesis by precipitation from magnesium sulphate and sodium metasilicate solutions, the magnesium silicate precursor was ball-milled with two immiscible liquids, forming a particle-loaded emulsion. Hexane formed the continuous phase; the droplet phase was formed by either acetonitrile, methanol, or water-methanol mixtures. Suspended precursor particles were refined, their fragments became trapped in the droplets, where they were eventually compacted into composite spheres. Prepared spherical powders were characterized using scanning electron microscopy, nitrogen sorption, and low angle laser light scattering. The synthesized powders exhibited narrow size distributions with modes from 3.3 to 92 μm. The spherical powders showed an enhanced flowability and had specific surface areas comparable to or higher than the precipitated precursor powders.