Enhanced pervaporation dehydration performance of ultrathin hybrid membrane by incorporating bioinspired multifunctional modifier and TiCl4 into chitosan

• Metal–catechol chelation was incorporated into an in situ sol–gel process.
• Ultrathin chitosan–titania hybrid membranes were prepared.
• Hydrophilicity and swelling resistance of the hybrid membranes were enhanced.
• Dehydration performance of the hybrid membranes was improved significantly.

3-(3,4-Dihydroxyphenyl)propionic acid (DHPPA) was introduced as a bioinspired multifunctional modifier to mediate the in situ sol–gel reaction of TiCl4 within chitosan (CS) matrix through metal–organic coordination. Ultrathin, robust chitosan–titania hybrid membranes were obtained in a facile way. The morphology, chemical and physical structures, as well as the hydrophilicity and thermal stability of hybrid membranes were extensively characterized. An ethanol/water mixture was chosen as a model system to evaluate the swelling resistance property and pervaporation dehydration performance of the hybrid membranes. The simultaneous enhancement of hydrophilicity and swelling resistance was achieved due to the presence of numerous carboxyl groups and the stable hybrid structure. The multiple interfacial interactions between polymeric and inorganic phases, as well as the steric effect of the bioinspired modifier, led to significant pervaporation performance enhancement of CS membrane. When the mass ratio of TiCl4 to CS was 14 wt%, the hybrid membrane exhibited the optimal pervaporation performance with a permeation flux of 1403 g/(m2 h) and a separation factor of 730 for 90 wt% ethanol aqueous solution at 350 K. The operation stability was also testified in long-term pervaporation separation test.