Vaterite Synthesis via Gas–Liquid Route under Controlled pH Conditions

Abstract

The purpose of this work was to obtain precipitated calcium carbonate (PCC) particles in polymorphic form of vaterite via gas–liquid route in controlled pH conditions. The effect of CO2 concentration (12.5–100%), feed gas (CO2–air) flow rate, pH, and conductivity of solution upon the PCC particles properties was studied. On the basis of the experimental data, the main factors leading to vaterite formation as major product were established. It was found that the buffer solution has a decisive role in determining polymorphic phase of PCC while CO2 concentration and feed gas flow rate have no significant influence. It was demonstrated that spherical vaterite particles of high purity can be produced under controlled reaction conditions. Also, some considerations on the mechanism of carbonation process were formulated.

Polymorphs of pure calcium carbonate prepared by the mineral carbonation of flue gas desulfurization gypsum

“…Ammonium ions facilitated the formation of vaterite, but their action is more reversible than those of polymers [33], and vaterite crystals formed in the presence of ammonium ions are easily transformed into stable calcite [17,19]. Based upon our previous results, it is obvious that compared to ammonia and water, ethanol binds more strongly to vaterite.…”

“…This is because NH 4 + interacts with the CO 3 2À present on the surface of the negatively charged crystal planes. Here, vaterite had a spherical morphology, which is its most frequently observed shape [17]. Spherical vaterite particles were formed in gelatinous amorphous CaCO 3 , resulting in spherulitic growth with a radiating pattern (see the magnified inset in Fig.…”

“…Although vaterite is the least thermodynamically stable among the anhydrous crystalline CaCO 3 phases, it is often observed at ambient temperature in the presence of ammonia/ammonium [17][18][19]. This is because NH 4 + interacts with the CO 3 2À present on the surface of the negatively charged crystal planes.…”

Studies on the utilization of post-distillation liquid from Solvay process to carbon dioxide capture and storage

“…In our experiments mainly vaterite particles were generated. This polymorph is less stable, and its formation is favored by prevailing local high saturation determined by a slightly alkaline pH, which inhibits the transformation of vaterite into calcite [22,23]. According to Takita et al [24] the presence of NaCl in the solution increases the solubility of calcium carbonate.…”

“…Spherical particles of vaterite can efficiently replace silica in the coating pigments, and they are also used in the production of paper. In addition, vaterite is used as a filler in polymeric composites, as it improves the degree of crystallinity, the crystallization temperature and the size of the composite spherulites [22]. The application of vaterite as an adsorbent for heavy metal ions removal is also examined [26].…”