Synthesis of vaterite CaCO<SUB>3</SUB> by direct precipitation using glycine and L-alanine as directing agents

We report room temperature synthesis of calcium carbonate (CaCO3) vaterite phase by the reaction of calcium chloride and sodium carbonate with glycine or l-alanine as directing agents. The compound crystallize in the hexagonal symmetry, P63/mmc with a = 4.1304(8) &#197; and c = 8.4770(2) &#197;

Thermogravimetric analysis of selected group (II) carbonateminerals - Implication for the geosequestration of greenhouse gases

The precursors of carbonate minerals have the potential to react with greenhouse gases to form many common carbonate minerals. The carbonate bearing minerals, magnesite, calcite, strontianite and witherite, were synthesised and analysed using a combination of thermogravimetry and evolved gas mass spectrometry. The DTG curves show that as both the mass and the size of the metal cationic radii increase, the inherent thermal stability of the carbonate also increases dramatically. It is proposed that this inherent effect is a size stabilisation relationship between that of the carbonate and the metal cation. As the cationic radius increases in size, the radius approaches and in the case of Sr2+ and Ba2+ exceeds that of the overall size of the carbonate anion. The thermal stability of these minerals has implications for the geosequestration of greenhouse gases. The carbonates with the larger cations show significantly greater stability