UNSTEADY-STATE, NONISOTHERMAL DISSOLUTION OF A SOLID PARTICLE IN LIQUID

The dissolution of solid particles in liquids has been analysed theoretically. Here, the heat of dissolution is taken into account. The unsteady state moving-boundary problem is solved through a perturbation approach. The perturbation parameter epsilon, defined as the ratio [(solubility - bulk solute concentration)/density of solid], can be used to determine whether the pseudo-steady state assumption often made in the conventional analysis is appropriate. The results of numerical calculations reveal that for the dissolution of non-dissociating substances in water if the variations in both the temperature and the concentration in the bulk liquid phase are negligible, the effect of heat on the kinetic behaviour under consideration is insignificant. Depending on the magnitude of epsilon, a pseudo-steady state assumption may lead to appreciable deviation.