engleski

Synthesis of uniform plate-like (001) calcite crystal seed

Calcium carbonate crystals are interesting model for studying the additive-controlled processes that are important for pharmaceutical industry and for understanding the crystallization in biological systems [1]. Calcite, the most stable calcium carbonate polymorph, can crystallizes with notable variety of habits under different environmental conditions. Indeed, it is known that the addition of inorganic ions such as Mg2+, SO42- or Li+ can exert profound effect on the morphology of calcite precipitated in aqueous systems [2]. Previously, it has been shown that increasing amounts of lithium ions enhance the formation of (001) calcite form [3]. Such crystals could be used as a good model for determination of adsorption mechanisms of organic molecules on the (001) calcite surface. The aim of this study was to prepare the plate-like and uniform calcite crystal seed, with well-developed (001) faces. For that purposes, the influence of the lithium ions concentration, in the range from c = 0.0 to 1.0 mol dm−3 and a mode of agitation have been systematically studied as a critical parameters of this specific CaCO3 precipitation process. Calcite samples were characterized by means of FTIR/ATR spectroscopy and PXRD. In addition, the SEM and AFM microscopy were used for identification and surface analysis of (001) faces, while the chemical composition of the precipitate has been determined by the ion chromatography. The results indicated that the addition of lithium ions has a significant influence on the polymorphic composition, as well as on the morphology of calcite crystals. It has been shown that the uniform, plate-like calcite is preferably precipitated after the addition of Li+ at concentration, c = 0.3 mol dm−3.

calcium carbonate ; lithium ; plate-like calcite

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