Pervaporation of benzene/cyclohexane mixtures through poly(vinyl alcohol) membranes with and without β-cyclodextrin

beta-cyclodextrin (beta-CD)-filled cross-linked poly(vinyl alcohol) (PVA) membranes (beta-CD/PVA/GA) were prepared using glutaraldehyde as the cross-linker, and these membranes showed strong benzene permselectivity. The permeation flux of beta-CD/PVA/GA membranes increased when the beta-CD content was 0-8 wt%, but permeation flux decreased slightly when the beta-CD content was 8-20 wt%. The separation factor towards benzene increased when beta-CD content was in the range 0-10 wt% and decreased slightly when the beta-CD content was 10-20 wt%. Compared with the beta-CD-free PVA/GA membrane, the separation factor of the beta-CD/PVA/GA membrane for benzene to cyclohexane considerably increased from 16.7 to 27.0, and the permeation flux of benzene increased from 23.1 to 30.9 g/(m(2)h) for benzene/cyclohexane (50/50, wt) mixtures at 323 K. The analysis based on the solution-diffusion model and beta-cyclodextrin inclusion phenomena (complex stabilities) revealed that beta-CD in PVA membranes played an important role as a caffier to partition benzene selectively from benzene/cyclohexane mixtures.