Rates and mechanisms of calcite growth and its inhibition by strontium

Abstract

In this work, calcite (calcium carbonate) growth is examined from computational, experimental and theoretical perspectives, specifically molecular dynamics rare event theory simulations and in situ atomic force microscopy (AFM). Simulations of attachment and detachment of ions to steps reveal a complex reaction chemistry, and the form of these reactions are begun to be incorporated into analytical expressions used to fit the monomolecular step velocities as a function of saturation index, aqueous calcium-to-carbonate ion concentration ratio, and aqueous strontium concentration. Regarding the latter, the effect of the impurity on growth rates is examined and it is found that the amount of strontium necessary to poison growth correlates with the aqueous calcium concentration, but not carbonate. This suggests that strontium interferes with the attachment of aqueous calcium ions.