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 frequently questioned, however, and needs to be improved. Ionic liquids are promising alternative solvents for membrane manufacture. We discuss general aspects of toxicity and recyclability in comparison to common organic solvents and take advantage of their unique capability of dissolution of polymers such as cellulose, a natural and biodegradable polymer. Cellulose membranes were prepared from solutions in 1-ethyl-3-methylimidazolium acetate as flat sheets and hollow fibers. The membrane performances were evaluated for oil and water separation, with analysis of the influence of anionic, cationic, and neutral surfactants added to emulsions with different oil contents.