Adsorption Based Competitive Purity Control In Crystallization

Impurities often have influence on crystallization and properties of the crystal product such as nucleation and growth kinetics, polymorphism or particle size and shape distribution. In most cases, these effects are undesired and thus purification of the product is necessary. This paper represents a novel purity control method based on competitive adsorption. Additive which competes with the undesired impurity for the available active sites on the crystal surface leads to changed adsorption equilibria and finally results lowered impurity concentration. This method is tested numerically by using the developed population balance model. The study shows that competitive purity control (CPC) which uses model based optimization can be an effective alternative for lowering undesired impurity concentration in the crystal product without additional purification steps in the production line.