Is the reactivity of calcium carbonate fully understood? A step forward using an atomic scale perspective

Abstract

Calcium carbonate (CaCO3) is an important component at the Earth’s surface, and it has many industrial applications. It forms rocks (limestone), coral reefs, and other biominerals; it affects the composition of natural waters, especially by dissolution, it is produced industrially, and it can form lime scale. Therefore, calcium carbonate has been a subject of a broad range of research and engineering fields and industries. A thorough understanding of all formation and dissolution processes that can take place is key in increasing the chance of success in research and development of new applications. I used molecular dynamic simulations to study the behaviour of calcium during different stages in the formation and dissolution of calcium carbonate from an atomistic perspective. I strengthened our knowledge, complementing experimental observations with molecular-scale mechanistic insights. I studied three different stages in calcium carbonate mineralization: the very first step, a dissolved calcium ion, to determine the local molecular environment and its properties. In the second step, I investigated the formation of the very first solids, calcium carbonate clusters that are formed with and without biomolecules. The third step describes a calcium ion at an already grown crystal surface. I evaluated the stability of calcium and the impact of magnesium, a very common impurity for calcium carbonate. My work brings a new understanding of the molecular mechanisms that are behind many of the large scale processes, the motors of what we see, even though it is far below our sense of reality in our daily life.