Mussel-inspired fabrication of structurally stable chitosan/polyacrylonitrile composite membrane for pervaporation dehydration

The structural stability of chitosan (CS)/polyacrylonitrile (PAN) composite membrane for pervaporation dehydration was improved by the introduction of mussel-adhesive-mimetic molecule, carbopol (CP). The composite membranes were simply fabricated by layer-by-layer technique, in which CP as an intermediate layer bridging the CS active layer and the PAN support layer. The structure and morphology of composite membranes were characterized by Fourier transform infrared spectroscopy (FT-IR) and field emission scanning electron microscope (FESEM). The methylene iodide contact angle measurement, T-peel test and molecular dynamics (MD) simulation were employed to analyze the wetting characteristics, adhesion strength and interaction at the interface. Positron annihilation lifetime spectroscopy (PALS) was employed to probe the fractional free-volume properties of the CS active layer. The membrane pervaporation performance was investigated by varying the molecular weight (CP981, 940, 974) and concentration of CP as well as the cross-linking degree of the CS active layer. When the concentration of CP974 was 0.5 wt.%, GCCS(60)/CP(0.5)/PAN composite membrane displayed the permeation flux of 1247 g/(m2 h) and separation factor of 256 for ethanol dehydration at 353 K. Furthermore, the enhancement of the long-term operation stability of membrane by incorporating the CP layer was also verified.