Preparation of crystalline Mg(OH)2 nanopowder from serpentinite mineral

Abstract

In this paper we describe a route to produce crystalline Mg(OH)2 nanopowders from serpentinite ore distributed in the Halilovskiy array (Russia, Orenburg region). An efficient extraction route consisting of treatment on serpentinite in 40% HNO3 at 80 °C followed by NH4OH titration for Mg(OH)2 precipitation was demonstrated. In this study, crystalline Mg(OH)2 nanopowders have been synthesized by solvothermal reaction method using (Mg(NO3)2⋅6H2O) which were obtained from serpentinite, NH4OH as a precipitator, and hydroxyethylated nonylphenol as surface-active substance. Microstructure and phase composition of samples were investigated employing scanning electron microscopy (SEM) and transmission electron microscopy (TEM), X-ray phase analysis (XRD), and inductively coupled plasma optical emission spectroscopy (ICP-OES). XRD reveals that Mg(OH)2 nanopowder with high purity has the brucite structure. It was found that crystalline Mg(OH)2 nanopowders exclusively consist of lamellar-like structures and the sizes of Mg(OH)2 are 30–265 nm length or width. Keywords: Serpentinite, Nitric acid leaching, Magnesium hydroxide, Solvothermal reaction method, Crystalline Mg(OH)2 nanopowder