Membrane-assisted crystallization: Membrane characterization, modelling and experiments

A hollow fiber membrane module was assessed for its potential in assisting crystallization processes. The membrane module was characterized in the sweeping gas membrane distillation configuration considering various solution and sweeping gas flow rates, temperatures and solution concentrations. A model, coupling mass and heat transfer, was developed to predict the membrane flux. The effect of the process conditions on the membrane flux was experimentally determined and the results were used to validate the model. Feed temperature and air flow rate were found to have a significant effect on the membrane flux. Having found the optimal process conditions for membrane distillation process, batch seeded crystallization experiment were performed to confirm the potential of membrane distillation in the generation of adequate rate and level of supersaturation. Since the desired supersaturation level could be maintained in the crystallizer while seeds were growing, it is confirmed that membrane distillation can be an efficient alternative to conventional supersaturation generation processes. Finally, comparing the modelling results with experiments confirms the acceptable accuracy and predictability capability of the developed model.