Ultrafiltration with organic solvents: A review on achieved results, membrane materials and challenges to face

Among all the available membrane processes, ultrafiltration is one of the most commonly used and industrially adapted. Apart from aqueous filtrations, the ultrafiltration of solvent-based solutions has found various applications. Some of them are the recovery of valuable compounds from agro-food industries (olive oil, wine, etc.) and the separation of solvents during edible oil production. However, the contact of the membrane (especially polymeric membranes) with an organic solvent still brings different challenges regarding permeate fluxes, rejection values and the long-term stability of the membrane. In this review, the results achieved by research works dealing with organic solvent ultrafiltration have been examined, analyzing the effects of the solvent on the process. Additionally, special attention has been paid to the pre-treatment of the membrane. All the applied strategies to pre-condition the membrane have been reported and discussed here. For the first time, all these relevant data have been formally structured and studied in-depth, aiming to gain more knowledge about organic solvent ultrafiltration.