Role of Hydrodynamics, Li+ Addition and Transformation Kinetics on the Formation of Plate-Like {001} Calcite Crystals

Abstract

Plate-like calcite crystals with expressed unstable {001} planes are interesting research model for investigations of interfacial interactions of different additive molecules, but also the crystal growth mechanisms. The aim of this study is to reproducibly prepare a significant amount of well-defined plate-like calcite crystals and to investigate the critical experimental parameters. Thus, in precipitation system c(NaHCO3) = c(CaCl2) = 0.1 mol dm−3, the influence of hydrodynamic parameters (mode of mixing of the reaction components) and a presence of lithium ions Li+ within a wide range of concentrations, 0.0 mol dm−3 < c(Li+) < 1.0 mol dm−3, have been studied. In addition, the kinetics of the solution mediated transformation of the initially formed metastable polymorph, vaterite, were followed in order to reproducibly describe the formation of stable calcite with expressed unstable morphology. The results indicate that the plate-like calcite is formed predominantly when the ultrasound irradiation is applied at c(Li+) ≥ 0.3 mol dm−3. On the other hand, when the magnetic and mechanical stirring are applied at higher Li+ concentrations, truncated rhombohedral crystals in a mixture with plate-like crystals are obtained. It was also found that the Li+ addition significantly prolonged the transformation, mainly by inhibiting the crystal growth of calcite.

Effect of pH and Type of Stirring on the Spontaneous Precipitation of CaCO3 at Identical Initial Supersaturation, Ionic Strength and a(Ca2+)/a(CO32−) Ratio

“…In our previous investigation [27] it was shown that pH and supersaturation are important and interconnected parameters that could influence the morphology, polymorphic composition and/or kinetics of CaCO 3 precipitation in precipitation systems with different chemical complexities. Apart from thermodynamic parameters, our investigations also showed that hydrodynamics has significant influence on calcium carbonate precipitation processes and on properties of CaCO 3 precipitated [29].…”

Regulation of Calcite Morphology by Low‐Molecular‐Weight Organic Acids: Alcohol Hydroxyl and Carboxyl Matters

“…It has been studied that the transformation kinetics of vaterite to calcite extend with increasing Li + concentration at ultrasonic irradiation condition. [ 18 ] Besides, atomistic simulation [ 24 ] and in situ AFM observations [ 25 ] showed that Li + could stabilize the energetically unfavorable (001) face by the site‐selective interaction to reduce its surface energy. This behavior will be expressed in the predominant growth of the uncovered faces and modification of the equilibrium calcite morphologies.…”

“…In this study, we investigated the role of alcoholic ─OH groups and carboxy groups of low molecular weight organic acids in calcium carbonate crystallization in the absent and present of Li + for considering the strong stabilizing effects of Li + on the {001} faces of calcite. [ 18 ] Five typical OAs of lactic acid (LA, CH 3 CH(OH)COOH, 1 alcoholic ─OH group and 1 carboxyl group), malic acid (MA, HOOCCH(OH)CH 2 COOH, 1 alcoholic ─OH group and 2 carboxyl groups), citric acid (CA, HOOCCH 2 C(OH)COOHCH 2 COOH, 1 alcoholic─OH group, and 3 carboxyl groups), succinic acid (SA, HOOCCH 2 CH 2 COOH, 0 alcoholic ─OH group and 2 carboxyl groups) and tartaric acid (TA, HOOCCHOHCHOHCOOH, 2 alcoholic ─OH groups and 2 carboxyl groups) derived from geological and biological mineralization were selected to study the regulatory effects of low molecular weight organic acids on calcite morphologies under mild conditions. The biomineralization ideas to synthesize calcite can not only help us understand the crucial role of alcoholic ─OH groups and carboxy groups of biomolecules in the regulation of calcite crystallization, but also help the clean synthesis of calcite to meet various chemical industry needs.…”

Electrochemically Assisted Growth of Hopper and Tabular Calcite under Confinement

“…Calcite crystals growing on mica continuously change their crystal habit from typical rhombohedra bounded by {104} planes to flat tabular plates exposing the (001) face. As the (001) plane of calcite is dipolar, composed of a sublayer of Ca or CO 3 , it is usually unstable in the absence of adsorbed species such as Li + ions 81,82 or organic additives. 83 In our experiments, calcite crystals can express (001) planes due to the combined effect of the oriented growth on mica and the spatial confinement of SFA.…”