Poly(vinyl alcohol)/chitosan blend membranes for pervaporation of benzene/cyclohexane mixtures

Poly(vinyl alcohol)/chitosan (PVA/CS) blend membranes were prepared by mixing the two polymeric homogeneous solutions. The interaction between PVA and chitosan arising from hydrogen bond was analyzed through intrinsic viscosity determination and Fourier transform infrared (FTIR) spectra, and there existed an incompatibility region in the blend membranes when chitosan content was 50 wt %. X-ray diffraction (XRD) showed that the crystalline structure of PVA and chitosan was disrupted through blending. The incompatibility of two polymers and disrupted crystalline structure led to a less compact structure. The blend membranes were used to pervaporative separation of benzene/cyclohexane (Bz/Chx) mixtures. The effects of chitosan content in blend membranes, weight fraction of benzene in feed, and operating temperature on separation performance of Bz/Chx mixtures were investigated. Compared with pure PVA and pure chitosan membranes, blend membranes showed much higher permeation flux and slightly higher benzene permselectivity. As the weight fraction of benzene in feed increased, separation factor decreased but total permeation flux increased. And it was observed that total permeation flux increased and separation factor decreased with increasing operating temperature. The total permeation flux of blend membrane with 50 wt % chitosan was 51.41 g/(m(2)h) and separation factor was 49.9 for Bz/Chx mixtures with 50 wt % of benzene at 323 K. (c) 2006 Wiley Periodicals, Inc.