Enhancement of Calcium Carbonate Precipitation in Seawaterthrough Carbonation Process

This study discusses the effect of Magnesium ions on the polymorphic crystallization of calcium carbonate by precipitating carbonate minerals from seawater solutions containing different concentrations of Magnesium ions at various temperatures. Precipitated calcium carbonate were synthesized via the carbonation process, the morphology changes and the particles structure were identified by the scanning electron microscopy, SEM and X-Ray Diffraction, XRD, respectively. The experimental results indicated that the concentration of Magnesium ions and temperature affect remarkably the calcite and aragonite formation. At lower suspension concentration, 0.5 M MgCl2, cubic calcite particles were formed; calcite coexisted with aragonite in medium suspension, 1.0 M MgCl2 and as the suspension grew higher, 1.5 M MgCl2, needle-like aragonite particles were obtained. As for the effect of temperature variations, the formation of calcite was favoured at lower temperature, 30°C. Aragonite starts to appear together with calcite as temperature increases at 50°C and 70°C. Relevant theories from literature were applied as reference in the experimental work and it was found that results obtained from the study corresponded to previous experiments done. Conclusively, the study has proven that Magnesium ion addition and temperature variation has effect on the morphology of precipitated calcium carbonate particles in seawater. These findings would be beneficial in contributing to the production of precipitated calcium carbonate due to the raw materials availability and their low costs, as well as natural sequestrating carbon dioxide and storing it in the form of CaCO3.