Effect of adsorbed impurities on the crystal growth of poorly soluble salts from slightly supersaturated solutions

Abstract

A model explaining the nonlinear dependence of crystal growth on the concentration of the impurity to be adsorbed in solution, impurity particle size, and surface coverage for poorly soluble salts at low supersaturations is proposed. The hypothesis about the adsorption of impurity particles on the terraces of crystals makes it possible to describe the evolution of growth steps using the model of crystallization at the potential relief. Analysis of the potential relief allows us to determine the critical surface coverage and the critical inhibitor concentration at which the crystallization is completely terminated. When the values of the surface coverage are lower than critical, the model predicts the near-exponential dependence of the crystallization rate on the surface coverage and impurity concentration, which agrees with the experimental data reported in the literature.