Dissolution kinetics of calcite at 50–70°C: An atomic force microscopic study under near-equilibrium conditions

Rice-like hollow nano-CaCO 3 synthesis

“…The dissolution of these particles discovered the fact that these particles were indeed in hollow shape with an empty space inside the particles. The growth rate and the dissolution rate were both higher at the edges of the rice-like particles because we think that the edges are the most energetic parts [36]. Interestingly, the hollow openings to the edges were closed up at the end of crystallization at step (6) and step (7) as a result of the dissolution and recrystallization of CaCO 3 particles in the solution [25,26,34,35].…”

Mechanical and physical behavior of high-porosity chalks exposed to chemical perturbation

“…Because dissolution changes the morphology of calcite surfaces progressively, the increase in the dissolution rate must be surface-related mechanisms. AFM studies (Shiraki et al, 2000;Xu et al, 2010) show that dissolution of calcite {104} surfaces occurs through rhombohedral pitch development where the crystallographic orientations determine the dissolution rate (Smith et al, 2013). These indicate that progression of calcite surface morphology through alteration of significant part of chalk volume is required before an increase in the dissolution rate starts.…”

Effects of magnesium ions on near-equilibrium calcite dissolution: Step kinetics and morphology

“…A mass flow controller (Porter Instrument) downstream of the cell was used to control fluid flow rate. A previous study (Xu et al, 2010) under similar experimental conditions demonstrated that step speed was independent of fluid flow rate at and above 1.4 l g/s. Thus a flow rate of 1.4 l g/s was used throughout our AFM experiments, ensuring that dissolution was limited by surface reaction instead of diffusive transport under our experimental conditions.…”

“…Saturation states of experimental solutions with respect to calcite ðX calcite Þ, ionic strengths, activities of ions, and pH values at the temperature of interest (50°C) were determined using Visual MINTEQ software. Details of MINTEQ calculations can be found in our previous publication (Xu et al, 2010). Briefly, in the MINTEQ calculations, aqueous solutions were first treated as partially open systems at room temperature, i.e., the partial pressure of CO 2 ðP CO2 Þ was modified for an open system such that the MINTEQ predicted pH agreed with the measured pH since the preparation of fresh NaHCO 3 solutions were in a state of disequilibrium with respect to atmospheric CO 2 .…”