Pervaporation of organic solvents by poly[bis(2,2,2‐trifluoroethoxy) phosphazene] membrane

Publisher Website
Google Scholar
Abstract
The permeation and pervaporation behaviour of water and several organic solvents through poly[bis(2,2,2‐trifluoroethoxy)phosphazene] (PBFP) membrane have been investigated in the temperature range from 42 to 80°C. The steady‐state permeation fluxes of the solvents increased in the following order: methanol > ethanol > benzene > water > cyclohexane. An Arrhenius plot of permeation flux of water suddenly changed in its gradient at about 66–70°C, which corresponds closely to the T(1) transition temperature (75°C) of PBFP studied. Interestingly, in the pervaporation of water‐methanol mixtures, methanol permeated more rapidly through the membrane than did water; however, the pervaporation of water‐ethanol mixtures showed poor permselectivties. In the case of an athermal mixture of methanol and ethanol, the fluxes of methanol and ethanol indicated convex and concave curves, respectively, to the axis of methanol concentration; thus the separation characteristics of this system were slightly better than those of a simple distillation technique. The pervaporation of benzene‐cyclohexane mixtures showed excellent permselectivty enrichment in benzene resulting in a separation factor of 12.