Preparation of monodispersed aragonite microspheres via a carbonation crystallization pathway

Abstract

Monodispersed calcium carbonate microspheres were prepared by carbonating a calcium acetate aqueous solution with CO 2 gas at a high pressure of 40 bar and a high temperature of 80 °C after 60 minutes of reaction. The products were characterized by X-ray powder diffraction (XRD) and scanning electron microscopy (SEM), respectively. The XRD pattern showed that the crystal polymorph of the as-prepared monodispersed microspheres was aragonite. The SEM images also displayed needle-like aragonite selforganized into microsphere superstructure with diameters ranging from 5 to 15 µm. Analysis of the formation mechanism of the calcium carbonate microsphere superstructure revealed that the rod-dumbbell-sphere morphogenesis mechanism along with the phase transformation of vaterite to aragonite was responsible for the growth of the monodispersed aragonite microspheres.

Experimental investigation of enhanced carbonation by solvent extraction for indirect CO2mineral sequestration

“…, the XRD pattern of the sample shows diffraction peaks consistent with JCPDS Card No. 00–005–0453, and it is almost the same as that of the sample obtained without magnesium acetate and organic solvent TBP addition, which investigated in our previous work . The peaks with 2 θ values can be correlated with pure aragonite, which further proved that magnesium acetate could not be reacted with CO 2 to form carbonate particle.…”

Vibrational spectroscopic characterization of growth bands in Porites coral from South China Sea

“…3, the peak at $133 cm À1 in XL1-1 showed a transition phase indicating which peak of vaterite at $120 cm À1 shifts to peak at $141 cm À1 of aragonite. Similarly, the peak at $178 cm À1 in XL1-1 showed a [19,[34][35][36]. In the present work, it is proposed that the vaterite could be the precursor of aragonite phase of coral skeleton from South China Sea.…”

Mesoporous Calcium Carbonate as a Phase Stabilizer of Amorphous Celecoxib – An Approach to Increase the Bioavailability of Poorly Soluble Pharmaceutical Substances

“…The amorphous calcium carbonate (ACC) in its pure form is highly unstable and transforms rapidly (within minutes) into any of its more stabile crystalline phases, if not otherwise stabilized during the synthesis 28, 29. The different crystalline CaCO 3 phases vary in morphology: calcite forms rhombohedral crystals, aragonite crystallizes into needles, while vaterite forms cauliflower‐like spheres or disks made up of smaller entities 27, 29, 30. The assembly of vaterite crystals into larger particulate structures makes the vaterite phase porous with a relatively high surface area as compared with denser calcite and aragonite particles 27, 29, 31, 32.…”