Polysulfone membranes are key tools in biomedical applications, such as hemodialysis and protein separation, in the food industry, and in seawater desalination. Ionic liquids are proposed as green solvent for membrane manufacture with tailored peptide selectivity.

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Ionic liquids have been considered green solvents for membrane fabrication. However, the high viscosity of their polymer solutions hinders the formation of membranes with strong mechanical properties. In this study, acetone was explored as a co-solvent with the ionic liquid 1-ethyl-3-methylimidazolium acetate ([EMIM]OAc) to dissolve cellulose acetate. The effects of acetone on the thermodynamic and kinetic aspects of the polymer solutions were studied and the physicochemical properties and separation capability of their resultant membranes were analyzed. The Hansen solubility parameters of [EMIM]OAc were measured by the software HSPiP and these data demonstrated that acetone was a suitable co-solvent to increase the solubility of cellulose acetate. The Gibbs free energy of mixing ΔG m was estimated to determine the proper composition of the polymer solution with better solubility. The study of the kinetics of phase separation showed that the demixing rate of the CA polymer solution in acetone and [EMIM]OAc was higher than that for solutions in [EMIM]OAc only. The membranes prepared from the former solution had higher water permeance and better mechanical stability than those prepared from the later solution. Adding acetone as a co-solvent opened the opportunity of fabricating membranes with higher polymer concentrations for higher separation capability and better mechanical properties.

PAN hollow fiber membranes with good pore morphology have been fabricated using solvent mixtures of ionic liquids and DMSO, which has a lower toxicity than other commonly used polar organic solvents.

Membrane processes are currently essential for seawater desalination and their implementation in sustainable separations in the chemical industry is rapidly growing. The sustainability of the membrane manufacture itself has been however frequently questioned and needs to be improved. Ionic liquids are promising alternative solvent for membrane manufacture. We discuss general aspects of toxicity and recyclability compared to common organic solvents and take advantage of their unique capability of dissolution of polymers like cellulose, a natural and biodegradable polymer. Cellulose membranes were prepared from solutions in 1-ethyl-3-methylimidazolium acetate as flat-sheet and hollow fibers. The membranes performances were evaluated for oil and water separation, analyzing the influence of anionic, cationic and neutral surfactants added to emulsions with different oil content.