Precipitation and Transformation of Vaterite Calcium Carbonate in the Presence of Some Organic Solvents

In this paper, the production of CaCO(3)particles via the carbonation route in the reaction of CaCl(2)and CO2, using NH(3)as a promoter of CO(2)absorption, was studied. The solvents used as the reaction media for CaCO(3)precipitation were aqueous solutions of methanol, isopropanol and dimethyl sulfoxide (DMSO), in a concentration range of 0-20% (v/v). It was found that the presence of an organic additive influenced the precipitation rate, the content of vaterite in the obtained product, the morphology and the size of the precipitated CaCO(3)particles, as well as the rate of its transformation into calcite. The presence of all added organic solvents reduced the vaterite concentration in the produced CaCO(3)both at the end of the reaction and after incubation in the reaction medium for 1 h. However, the transformation of vaterite particles into calcite in the tested solutions was slower when the 4 h and 24 h procedures were compared. The interactions of solvents with calcite and vaterite were compared using HPLC tests. DMSO molecules interacted with vaterite particles the most strongly, while the interaction of isopropanol with this polymorph was the weakest. The opposite effect was observed for interactions with calcite particles, and the affinity decreased in the series: isopropanol, methanol, DMSO.