This article presents a novel assessment method for secondary nucleation rates using a well-controlled, small scale seeding procedure. The procedure comprises the seeding of a well-monitored, stirred, supersaturated solution by a carefully selected single crystal under conditions at which spontaneous nucleation does not occur. The determined number of particles in time were translated to a suspension density using a calibration performed with monodisperse polymer spheres. The increasing crystal suspension density in time subsequently allowed the determination of the secondary nucleation rate under very specific conditions of supersaturation and temperature. The secondary nucleation rate was measured as a function of seed crystal size and supersaturation. It was observed that the time elapsed between the moment a single seed crystal is added and the moment the suspension density started to increase is larger when the seeded crystals are smaller and the supersaturation is lower. A systematic study of secondary nucleation at different supersaturations led to the determination of a supersaturation threshold for secondary nucleation, which could be used in industrial crystallization process design to identify process conditions with the right secondary nucleation rate behavior.
- secondary nucleation rates
- small scale seeding procedure
- single crystal