Influence of impurity metal doping on calcite growth: A first-principles study

To better understand the effect of impurity metal doping on the initial stage of calcite growth, the attachment of the CaCO3 molecule on anhydrous and hydrated pristine and doped (Mg-, Cu-, Zn-, Sr- and Ba-doped) calcite (101¯4) surfaces and the analysis of the interactions of the water molecule with various dopants were studied using the first-principles methods. Simulation results suggest that the adsorption ability of anhydrous calcite surfaces toward the CaCO3 molecule is determined by the size of the dopant. The adsorption behavior for water molecules is dominated by chemical bonding. For the adsorption of the CaCO3 molecule on hydrated calcite surfaces, both the dopant size and the chemical bonding factors influence its stability, resulting in the decrease of the CaCO3 adsorption on all doped surfaces. By considering synergetic effects of impurity metal doping on the water and CaCO3 adsorption, we provide new insights into the understanding of the inhibiting mechanism of Mg, Cu and Zn impurities on calcite growth. Moreover, the predicted facilitation of Sr and Ba dopants on calcite growth highlights the feasibility of applying the calcite precipitation technique in mineralizing toxic Sr and Ba from contaminated environments.