Solubility of Artinite

抄録

Detailed analysis of a natural artinite sample by XRD, TGA, FTIR, Raman and solid state ¹³C CP MAS NMR confirmed a high purity of the sample as well as a crystal structure containing a single carbonate site. The solubility of artinite was experimentally investigated under varying saturation conditions. Undersaturation experiments at 7 to 25 °C, up to 1 year, showed that artinite remained stable in water, and that its solubility was higher than previously estimated in literature. In oversaturation experiments, initially dypingite formed at 7 to 20 °C, which slowly transformed into artinite and hydromagnesite. At 25 °C, no dypingite formation was observed, while initially formed artinite transformed to hydromagnesite within a year. Solubility products for artinite, dypingite, and hydromagnesite at 7, 15, 20 and 25 °C were derived from experimental and literature data. The thermodynamic data allowed calculating the impact of CO₂ pressure and temperature on the stability of magnesium carbonate and hydroxide phases and confirmed that hydromagnesite is more stable than dypingite, artinite, and nesquehonite under near-ambient conditions. Increased CO₂ partial pressure stabilizes nesquehonite while artinite becomes less favored. The revised artinite solubility product indicates that artinite is thermodynamically less stable than hydromagnesite, consistent with observations in MgO-hydromagnesite cements.