Synthesis of nesquehonite by reaction of gaseous CO2 with Mg chloride solution: Its potential role in the sequestration of carbon dioxide

In this paper is reported a novel method to synthesize nesquehonite, MgCO3·3H2O, via reaction of a flux of CO2 with Mg chloride solution at 20 ± 2 °C. The reaction rate is rapid, with carbonate deposition almost complete in about 10 min. The full characterization of the product of synthesis has been performed to investigate its potential role as a “CO2-sequestering medium” and a means of disposing Mg-rich wastewater. We investigated the nesquehonite synthesized using SEM, XRD, FTIR and thermal analysis. The thermodynamic and chemical stability of this low-temperature hydrated carbonate of Mg and its possible transformation products make our method a promising complementary solution to other methods of CO2 sequestration. Carbonation via magnesium chloride aqueous solutions at standard conditions represents a simple and permanent method of trapping CO2. It could be applied at point sources of CO2 emission and could involve rejected brine from desalination plants and other saline aqueous wastes (i.e., “produced water”). The likelihood of using the resulting nesquehonite and the by-products of the process in a large number of applications makes our method an even more attractive solution.