Experimental and molecular simulation investigations on interfacial characteristics of gelatin/polyacrylonitrile composite pervaporation membrane

The structural stability and separation performance of composite membrane can be tuned by the interfacial compatibility and interaction between the active layer and the support layer. Inspired by the bioadhesion phenomena and principle, gelatin (GE) was employed directly as the active layer in this study due to its superior film forming property and multiple interactions with the polyacrylonitrile (PAN) support layer. GE/PAN membranes were prepared via facile and controllable dip-coating method under mild conditions. Both experimental investigation and molecular dynamics (MD) simulation were utilized to probe the interfacial compatibility and the interfacial interaction of the composite membranes. SEM and solubility parameters indicated the moderate interfacial compatibility, while T-peel test, interfacial energy and mean-square displacement data demonstrated the strong interaction between the active layer and the support layer. The physicochemical properties of composite membranes were characterized by Fourier transform infrared spectroscopy (FT-IR), contact angle measurement and positron annihilation lifetime spectroscopy (PALS). The pervaporation experiments using ethanol/water mixture as the model system showed that the membrane acquired the highest pervaporation performance (permeation flux of 1.08 kg/(m2 h), separation factor of 298) when GE concentration was 2 wt.% and the mass ratio of GA to GE was 2.50 wt.% in the membrane casting solution.