Glycine-Mediated, Selective Preparation of Monodisperse Spherical Vaterite Calcium Carbonate in Various Reaction Systems

Abstract

Selective formation of monodisperse spherical vaterite calcium carbonate (CaCO 3 ) precipitate using glycine (Gly) in a calcium hydroxide (Ca(OH) 2 )-carbon dioxide (CO 2 ) reaction system at room temperature and atmospheric pressure is reported. Crystalline products were examined by scanning electron microscopy, powder X-ray diffraction, Fourier transform infrared spectrometer, Raman spectra and laser particle size analysis. The experimental results suggest that increasing Gly concentration caused inhibition of the nucleation and growth of calcite and promoted the formation of vaterite. By adjusting the content of additive Gly, the crystalline product was almost monodisperse spherical vaterite CaCO 3 . The resulting product had good thermal stability, still keeping its crystal type, spherical shape, and size after being heated above 350°C. Mechanism studies illustrated that the complex effects between Gly and Ca 2+ played the key role in the formation process of monodisperse spherical vaterite CaCO 3 . Further studies indicated that this method might also apply to other reaction systems, such as CaCl 2 -NH 3 ·H 2 O-CO 2 and CaCl 2 -Na 2 CO 3 reaction systems. These studies are paving the way for industrial preparation and further commercial applications of monodisperse spherical vaterite CaCO 3 .

Calcium Carbonate@silica Composite with Superhydrophobic Properties

“…This is the same as the standard X-ray diffraction pattern for calcite, indicating that the prepared cubic micron calcium carbonate crystal form is mainly calcite. The diffraction peaks of spherical calcium carbonate (Figure 4b) appear at 20.81 for vaterite [53], the diffraction peaks at 29.35 • agree with the standard X-ray diffraction pattern for calcite, indicating that the spherical calcium carbonate mainly has vaterite [54]. Figure 4c shows the X-ray diffraction pattern of silica, the intense broad peak at 2θ = 24 • represents the amorphous silica due to the smaller particle size effect and incomplete inner structure of the spherical nanoparticles [55].…”

Investigation of calcium carbonate synthesized by steamed ammonia liquid waste without use of additives

“…6 It has been well established that the different polymorphs of CaCO 3 synthesized in an aqueous solution possess different morphologies: rhombohedral phased calcite is usually found as cubic particles, orthorhombic aragonite usually found as needle-like particles, while vaterite has a hexagonal structure that normally leads to spherical particles, 7 the CaCO 3 morphology, size, crystal structure, density, color, brightness and other physicochemical properties of a material are strongly dependent on its preparation technology. Several techniques have been used to manufacture special morphologies, different polymorphs, controllable size, well dispersed CaCO 3 , such as carbonation, [8][9][10][11][12] solvo or hydrothermal synthesis 12,13 , microwave-assisted synthesis, [14][15][16][17] sonochemical synthesis, 18 double water-in-oil-in-water emulsion, 19 wet precipitation 20,21 and other special synthesis processes and methods. 22 Now, precipitation method is the most important method to prepare CaCO 3 , the relationship between precipitation conditions and morphology of CaCO 3 is the object of many experimental studies but it still is disputed, 23 it has been reported that synthetic factors including concentration of reactants, stirring speed, Ca 2+ : CO 3 2À ratio, aging time and adding mode may signicantly affect the formation of the polymorphs CaCO 3 .…”

Glycine-Induced Synthesis of Vaterite via Direct Aqueous Mineral Carbonation of Flue Gas Desulfurization Gypsum

“…The exothermic peak near 498°C is due to the phase transformation of vaterite to calcite under high temperature. The TG results further showed that there was a small amount of glycine in CaCO 3 products, which could stabilize the metastable vaterite and prevent it from transforming into calcite (Lai et al 2015;Luo et al 2015).…”