In-situ formation of polyether membrane selective layer for pervaporation separation of azeotropic organic solvent mixtures

Pervaporation technology is suitable for separating organic solvent azeotropic mixtures or isomers that are challenging for traditional distillation methods. However, the conventional methods to fabricate pervaporation membranes often lead to limitations in membrane performance and stability, such as the restrictiveness of material selection and the high costs of manufacturing. Herein, we utilized commercially available inexpensive monomers CE (3,4-Epoxycyclohexylmethyl) and DOX (3-ethyl-3-[(3-ethyloxetan-3-yl)methoxymethyl]oxetane), along with the sulfonium salt photo-initiator (Ar6S 2+ SbF 6- ), to fabricate pervaporation membranes through cationic photopolymerization, resulting in separation layers enriched with ether groups. The resulting pervaporation membranes were employed to separate ethanol/n-hexane and ethanol/cyclohexane azeotropes formed during the production of ethyl acetate. The separation efficiency was significantly enhanced compared to the original PVDF membranes, achieving a separation factor of up to 162.81 for ethanol/n-hexane azeotrope and 41.89 for ethanol/cyclohexane azeotrope. During the 110-hour prolonged operation test, the membranes demonstrated exceptional tolerance and long-term stability against different organic solvents.