(92d) Stabilization and Coagulation of Colloidal Suspensions during Crystallization

In colloidal suspension, the disordered colloidal particles could be rearranged under the artificial control, which show great potential in some areas like nanomaterials, energy and biomedicine. However, colloidal suspension could be catastrophic for the phase separation process like crystallization. Due to the high viscosity, colloidal suspension would be a great burden on the equipment, which cause the clogging in pipeline and difficulty in stirring. In addition, due to the collapse of the colloidal suspension, impurities and solvents trapped significantly affect the purity of the final product. Hence, understanding the motion and interaction of particles are crucial and instructive to control the colloid suspension during crystallization. Due to the special thermodynamic properties of cefradine, the mutation of supersaturation usually led to the explosive nucleation, resulting in the formation of large amounts of nanocrystals as the colloidal particles. Via surface analysis of nanocrystal and molecular simulation, the electric double layer on ionized crystal surface was revealed. Then, DLVO model was further derived to analyze interaction between particles. Combining dynamic light scattering, zeta potential measurements and rheology, the stability of colloidal suspension and motion behavior of particles was understood during the whole crystallization process. The developed knowledge based on the suspension can form a basis for further optimization of purification and crystallization for cefradine.