Permeation of Water through Cation Exchange Membranes

Water permeabilities as well as other membrane parameters, such as exchange capacity, water content, and specific conductance, have been measured for two cation exchange membranes in the H form. The conductance of membrane with low water content was less than that of the membrane with high water content. These data have been discussed in the light of an existing theory and found inadequate to explain the results in a quantitative way. Water permeability of the membranes subject to mechanical pressure was found to be higher than their isotopic water permeability, according to expectation. These data have been examined from the standpoint of thermodynamic and kinetic theories of water flow in membranes and used to estimate the average size of membrane pores

Ion Association of Simple Electrolytes in Water Saturated 1-Butanol

The electrical conductances of solutions of physiologically important simple electrolytes in water saturated 1-butanol have been measured at 25°C as functions of salt concentration. Values for both λ(o), the conductance at infinite dilution, and K, the dissociation constant, have been derived by subjecting the data to the procedures given by Shedlovsky and Fuoss

Studies with Composite Membranes: II. Measurement of Asymmetric Properties

Electrical potentials arising across composite membranes when they separate the same concentration of a (1:1) electrolyte or electrolytes have been measured. These potentials have been shown to arise from differences in the transport number of counterions contacting the two faces of the membrane which contained in its body a high concentration of electrolyte and polyelectrolyte. When the concentration of this trapped electrolyte or polyelectrolyte is low, the asymmetry potentials are small. Although measurements of current-voltage relations provided evidence for the existence of asymmetry between the two faces of the membrane, osmotic flow of water in either direction across the membrane and the salt flow in the two directions were symmetrical. These solvent and solute flux measurements lasted more than 30 hr. Short-term (about 4 hr) flux measurements, however, using tritiated water (THO), gave flows which were different in the two directions. Similarly, the salt flows measured using (22)Na isotope were different in the two directions. The usefulness of the present system as a model to use for studies concerned with carrier transport problems in biology has been pointed out

Studies with Composite Membranes: III. Measurement of Water Permeability

The permeability of tritiated water (THO) across simple and layer-type composite membranes of collodion containing different amounts of polystyrenesulfonic acid has been measured and corrected for the effects of aqueous stationary layers present at the membrane-solution interfaces. It was found that the water permeabilities in the two opposite directions across the composite membranes were different, whereas they were the same across simple membranes. The theoretical permeability value for the composite membrane (formed by putting one simple membrane on top of another simple membrane of increasing charge density and gently pressing them together), calculated from the values due to simple membranes, was found to be always greater than the two measured values. It was shown that the aqueous layers trapped between membranes were not responsible for the low measured values. The factor causing this was ascribed to the mechanism which produced rectification of water flow in the composite membranes. Establishment of the THO concentration profile in the layered membranes showed that accumulation and depletion of THO in the membrane phase when the THO was flowing from the high charge density side to the low charge density side and vice versa, respectively, were responsible for the unequal flows observed across the composite membrane in the two directions