Crystallization of CaCO3in the Presence of Ethanolamine Reveals Transient Meso-like Crystals

This paper presents a study on the influence of ethanolamine (ETH), an anticorrosion agent, on the polymorphism, morphology, and size distribution of calcium carbonate crystals after room-temperature synthesis. The pH of the solution, the presence of the additive, and the time of crystallization are proved to be important parameters for the morphogenesis of calcium carbonate. Morphologies as diverse as spherulite, rhomobohedral, and scalenohedral micrometric crystals, as well as submicrometric platelike particles, are produced. The mechanism of calcite formation in the presence of ETH involves a mesocrystal transient phase that evolves into classical single crystals. The key parameter of this process is supposed to be the ETH coverage of the primary calcite particles. In particular, it was found that, in particular conditions in the presence of ETH, nanoaggregates of calcium carbonate are formed, which are not stable and, with time, tend to convert into classical rhombohedral crystals of bigger dimensions. This study is relevant for the understanding of basic processes of calcium carbonate precipitation and has a potential applicative impact in the field of restoration when nanomaterials able to penetrate into the porosity of the materials are needed with the aim of reducing the acidity such as on corroded metallic objects or for the deacidification of paper supports. (Chemical Equation Presented).