Polymeric hollow fiber membrane for cooling crystallization seeding: On the mechanism of induced nucleation based on thermal transfer

Cooling crystallization is an important separation process and particuology technology that requires accurate nucleation control strategies. Herein, we introduced the polymeric hollow fiber membrane with proper thermal properties as the effective nucleation induction interface during cooling crystallization. The heterogeneous nucleation control mechanism was introduced based on classical nucleation theory and the thermal transfer process. Interfacial properties and the thermal conductivity of two kinds of polymeric membranes, polytetrafluoroethylene (PTFE) and polyethersulfone (PES), were measured and simulated with the developed model. These two membranes possessed different nucleation induction periods, nucleation rates and crystallization performances, which validated that the hollow fiber membrane module could effectively accelerate the nucleation process compared to conventional cooling crystallization owing to the shorter nucleation induction period and the reduced solution surface tension. Due to the higher hydrophobicity and the lower roughness of the membrane surface, the PTFE membrane possessed a more moderate performance in generating stable heterogeneous nucleation than the one of PES membrane. Thus, the adjustable membrane property enabled the hollow fiber membrane-assisted cooling crystallization to possess the accurate nucleation control and desired terminal particle products.