Crystallisation kinetics of calcite from calcium bicarbonate solutions between 278.15 and 303.15 K

Abstract

The temperature dependence of calcite crystal growth from dilute Ca(HCO₃)₂ solutions has been investigated between 278.15 and 303.15 K using the seeded growth method with two different specific surface area calcite samples. The results are interpreted using both the Davies and Jones rate equation and the surface reaction mechanistic model. The surface concentration of CO₂ is predicted using the mechanistic approach. The best agreement with the data is obtained by assuming the reaction between [Ca–HCO₃]⁺ ion pair and surface CO^2–₃ anion sites. This mechanism leads to a mean energy of activation for both samples of 45.8 ± 4.3 kJ mol^–1. Assuming the B.E.T. specific surface areas, the two seed materials were found to exhibit different reaction site densities.