Kinetics of the dissolution of sand into alkaline solutions: application of a modified shrinking core model

The batch dissolution kinetics of sand particles in concentrated alkaline sodium hydroxide solutions was investigated at high temperature and high pressure. The influence of the particle size, the operating temperature (150–220 °C) and the hydroxide ion molality on the kinetic rate were studied. Experimental data fit well into a developed model based on the shrinking core model approach in which a variable activation energy term was introduced. Kinetic analysis of the experimental results reveals that the associated energy and the rate-controlling mechanism are dependent upon both sample temperature as well as the extent of the reaction.