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

Abstract

SynopsisThe permeation and pentaporation behavior of water and several organic solvents through polyIbi~(2,2,2-trihoroethoxy)phoaphazme] (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 6&70"C, which corresponds closely to the T(1) transition temperature (75'0 of PBFP studied. Interestingly, in the pervapohition of water-methanol mixtures, methanol permeated more rapidly through the membrane than did water; however, the pervaporation of water-ethanol mixtures showed poor permselectivitiea In the case of an athermal mixture of methanol and ethanol, the fluxes of methanol and ethanol indicated convex and concave curveq 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 permselectivity enrichment in benzene resulting in a separation factor of 12.

Conformational stability and force field of short-chain linear chlorophosphazenes: MNDO calculations, phosphorus-31 NMR, vibrational spectra, and normal coordinate analyses of Cl3PN(PCl2N)nP(O)Cl2 and [Cl3PN(PCl2N)nPCl3][PCl6] (n = 1, 2)

“…[16][17][18][19][20] Some are elastomeric at room temperature. These elastomeric properties are in relation to the flexibility of the phosphazene backbone^.…”

Transport properties of a side‐chain liquid‐crystalline polymer. Poly(4‐acryloyloxy biphenyl)

“…An increase of permeability to water in a membrane of polyphosphazene, in a range of temperature corresponding to the transition from three-dimensional to two-dimensional order, was interpreted as due to an increase of fractional free volume, without taking explicitly into account possible transport through the mesophase. 21 Recently, Loth and Eushen2' reported on the diffusion of salicylic acid through a polymeric membrane formed by a liquid-crystalline side-chain polysiloxane elastomer with various contents of the mesogenic moiety. The permeability of the membrane was quite low and decreased on increasing the content of the mesogenic monomer.…”

Transport Properties of Polyphosphazenes

“…Uragami and Morikawa [69] have investigated the pervaporation and evapomeation of aqueous solutions of methanol and ethanol in PTFEP. Suzuki et al [70] have studied the pervaporation of water and several organic solvents in PTFEP over the temperature range 42 to 801C. Permeation fluxes increased in the order methanolWethanolWbenzeneWwaterWcyclohexane.…”