Divisive Effect of Alcohol−Water Mixed Solvents on Growth Morphology of Calcium Carbonate Crystals

Abstract

Controlling the process of crystal growth is of importance to the biomineralization and materials science. In this work, some novel morphology of calcium carbonate (CaCO 3 ) was precipitated in an ethanol-water binary solvent (EWBS) with a CaCl 2 /Na 2 CO 3 reaction system. For the solutions of CaCl 2 /Na 2 CO 3 in EWBS, the alcoholization and hydration of Ca 2+ and CO 3 2were discussed from the radial distribution functions by molecular dynamics simulations, and the number density profiles of water molecules around and ∼15 Å away from CO 3 2were employed to reveal the distribution of water molecules. It is found that EWBS has a divisive effect on Ca 2+ and CO 3 2-, and the local inhomogeneity of EWBS would be enhanced by adding some Na 2 CO 3 into it. This inhomogeneity results in an aqueous two-phase system as x E goes up to 0.7. In addition, the novel morphology of CaCO 3 under different molar ratios of Ca 2+ /CO 3 2and in different mixed solvents were confirmed by XRD and SEM, and the relationships between the morphology of CaCO 3 and the structural properties of mixed solvents were further explored.

Synthesis of calcium carbonate in trace water environments

“…[26][27][28] In addition, Anhydrous calcium chloride and ammonium carbonate were dissolved in absolute ethanol, and then the solutions were added to absolute ethanol, or other alcohols, using syringe pumps under continuous magnetic stirring until the desired concentration was reached (see the Experimental section in the ESI †).…”

Crystallization of CaCO3in Water–Alcohol Mixtures: Spherulitic Growth, Polymorph Stabilization, and Morphology Change

“…For example, Zhou et al 42 precipitated vaterite with a wide range of morphologies, including cauliflower spheres, by varying pH, Ca/CO 3 ratios and temperature, without using alcohol. Furthermore, Manoli and Dalas 16 reported the development of two different types of cauliflower spheres by varying the type of alcohol (ethanol, isopropanol, and diethylene glycol), and Zhang et al 24 reported that cauliflower vaterite formed in the presence of ethanol but accompanied by aragonite. They concluded that by varying the Ca/CO 3 ratio, they could define the relative proportions of aragonite and vaterite.…”

“…Zhang et al 24 investigated the alcoholization and hydration of Ca 2+ and CO 3 2− , using molecular dynamics simulations. They reported that CO 3 2− ions in ethanol−water mixtures are mainly solvated by water and hardly dissolve in ethanol, whereas Ca 2+ ions are solvated both by water and by ethanol.…”

Phase and morphology evolution of vaterite crystals in water/ethanol binary solvent

“…Vaterite precipitates were prepared by a chemical reaction in water-ethanol binary solvent by mixing WEBS solutions of Na 2 CO 3 and CaCl 2 , as reported in our previous paper [13]. under these conditions.…”

“…Morphology and phase evolution of vaterite crystal in WEBS was under research. Using theoretically calculated data [13] of calcium carbonate, we tried to interpret the experimental results.…”