Fabrication of cellulose acetate membrane using deep eutectic solvent for water/isopropyl alcohol pervaporation

Abstract

Deep eutectic solvents (DES) are eco-friendly alternatives to conventional organic solvents and have receive significant attention due to their low cost and biodegradable properties. These characteristics provide DES highly suitable for membrane applications. In this study, cellulose acetate (CA) membrane is fabricated using DES. The DES is prepared by mixing thymol (Thy) and decanoic acid (DA). CA is dissolved in the DES and the solution is casted into a film to fabricate non-porous membranes by phase inversion method. To find the optimum solvent for CA, various types of DES are tested with different compositions of which Thy and DA, both naturally occurring chemicals, are selected. Variations in membrane structure and performance are also analyzed by altering the ratio of Thy to DA. Additionally, it is confirmed that DES is completely removed during the phase inversion process after casting the CA dope solution, demonstrating that DES functions solely as a solvent and not as an additive. The fabricated non-porous CA membranes are applied for dehydration of a water and isopropyl alcohol mixture via pervaporation. The membranes exhibit a high flux of 5.381 kg/m²·h and a selectivity of 16. Both DES and CA are biodegradable and biocompatible, yielding viable substitutes for the toxic and harsh organic solvents traditionally used in membrane fabrication.