A study of the effects of NH4+ on the fast precipitation of vaterite CaCO3 formed from steamed ammonia liquid waste and K2CO3/Na2CO3

Abstract

Vaterite-phase calcium carbonate (CaCO₃) has many unique properties, such as high solubility, a spherical shape, a large surface area, and porosity, giving it more industrial applications than calcite and aragonite-type polymorphs. However, it is difficult to achieve its large-scale industrial production owing to its poor thermodynamic stability. In the present study, steamed ammonia liquid waste (CaCl₂) was utilized to fabricate vaterite CaCO₃ using a fast fabrication technique. The effects of the NH₄⁺ concentration on the CaCO₃ particle size, crystal structure, morphology, and chemical purity were investigated. The results show that the CaCO₃ morphology, size, and crystal phase were influenced significantly by the NH₄⁺ concentration. NH₄⁺ had more influence on the crystallization process of CaCO₃ when using Na₂CO₃ as a carbon source than when using K₂CO₃ as a carbon source. An examination of the mechanism showed that the NH₄⁺ ions could be bonded to the original vaterite nanoparticle surface. Hence, the crystal growth polymorph could be controlled and vaterite phase transformation could be prevented.