Preparation of Uniform Needle-Like Aragonite Particles by Homogeneous Precipitation

• Published in: Journal of colloid and interface science Vol. 218; no. 2; pp. 545 - 553
• Main Authors: Wang, Laifeng, Sondi, Ivan, Matijević, Egon
• Format: Journal Article
• Language: English
• Published: San Diego, CA Elsevier Inc 15.10.1999; Elsevier
• Subjects: aragonite needles; calcite colloidal; calcium carbonates monodispersed; Chemistry; Colloidal state and disperse state; Exact sciences and technology; General and physical chemistry; Physical and chemical studies. Granulometry. Electrokinetic phenomena; vaterite colloidal; calcite colloidal; calcium carbonates monodispersed; vaterite colloidal; aragonite needles; Non ionic surfactant; Ageing; Stirring; Temperature effect; Sodium compound; Experimental study; Sulfates; Calcium chloride; Operating conditions; Sulfonate; Dextran; Ethylene oxide polymer; Anionic surfactant; Aragonite; Urea; Precipitation; Pyrrolidone(vinyl) polymer; Preparation; Calcium carbonate; Concentration effect; Uniformity
• ISSN: 0021-9797; 1095-7103
• DOI: 10.1006/jcis.1999.6463

Uniform needle-like aragonite particles were obtained by aging solutions of calcium salts in the presence of urea at 90°C. The effects of various experimental conditions, such as the concentration of reactants, temperature, aging time, agitation, mixing procedure, and the addition of divalent cations, surfactants, and polymers, on the precipitation of aragonite were investigated. It was found that the formation of different polymorphs of calcium carbonate was affected mostly by agitation and concentration of reactants, as well as by the mixing procedure. Thus, under otherwise the same experimental conditions, needles of aragonite were formed without stirring or at low-power ultrasound; rhombohedral calcite appeared when aging experiments were carried out under the influence of magnetic stirring, while irregular particles of mixed vaterite and calcite crystal structure were generated at higher CaCl2 concentrations. Mixing the preheated reactant solutions resulted in unique “flower-type” vaterite particles. Finally, the presence of sulfonate or sulfate ions promoted precipitation of vaterite and calcite.