Calcium hydroxide dissolution rates: Dependence on temperature and saturation

Calcium hydroxide plays a crucial role in various industrial processes. As a primary component of lime mortars , it also facilitates water treatment and supports food processing applications, including pickling and fruit drink fortification. Within portland cement , serves as a key reactant in pozzolanic and carbonation reactions and leaches first from concrete binders when exposed to water. dissolution influences each of these processes. However, limited data exist on how its rate responds to the thermodynamic driving force and temperature changes. This paper presents dissolution rate measurements, using them to determine the apparent activation energy of the rate constant and to identify regimes where different rate-controlling mechanisms dominate. The experiments combine slurries with partially saturated solutions in a vigorously stirred mixed flow reactor that maintains steady-state solution composition. The data reveal a rate equation that explains how surface-controlled dissolution occurs, following chemical kinetic theory . This equation refines numerical cement hydration models involving leaching, carbonation, and pozzolanic reactions . • Dissolution rates of Ca(OH) 2 are measured with a mixed flow reactor. • Ca(OH) 2 dissolution rates have Arrhenius behavior only at zero saturation. • The dissolution mechanism changes from low to high undersaturations. • A rate equation is fit as a function of temperature and saturation index.