Membrane assisted crystallization of salt crystals: membrane modeling

Crystallization is one of the most widely applied separation processes in the chemical industry and the interest to combine membrane operations and crystallization has increased recently. Membrane crystallization (MCr) is emerging as a promising technique with some important advantages with respect to traditional crystallization processes: well-controlled nucleation and growth kinetics, fast crystallization rates and reduced induction time, membrane surface promoting heterogeneous nucleation and control of supersaturation level and rate. In a membrane crystallizer a hydrophobic membrane matrix acts as a selective gate for solvent evaporation and allows to modulate the final degree and the rate for the generation of the supersaturation. Therefore, the possibility to act on the trans-membrane flow rate allows to control and address the final properties of the crystals produced both in terms of structure (polymorphism) and morphology (habit, shape, size, and size distribution). In this work molecular simulations have been performed to give insights on the experimental results. The NaCl crystallization process at a PVDF and PP membrane interface was performed by using molecular dynamics simulations. The simulation have been developed for predicting variations in the crystalline form in function of cross velocity. REFERENCES Macedonio F. and Drioli E. (2010) "Hydrophobic membranes for salts recovery from desalination plants", Desalination and Water Treatment 18(1-3), 224-234 Drioli E., Di Profio G., Curcio E. (2015) "Membrane-Assisted Crystallization Technology" World Scientific