Measurements of Membrane Permeabilities Using a Rotating Batch Dialyzer

Abstract

The rotating batch dialyzer, an exceptionally simple cell for measuring membrane permeabilities, has been characterized in terms of boundary layer permeabilities for six solutes diffusing through Cuprophane. An empirical expression was obtained for calculating boundary layer permeabilities from known values for the rotational speed of the cell, the density and viscosity of the solutions, and the diffusion coefficient of the solute in solution. Permeabilities determined with the rotating cell were confirmed for three solutes by comparing results from an entirely different type of cell, the flat plate dialyzer.

A New Technique for the Determination of Overall Mass‐transfer Coefficients in Continuous Dialyzers

“…The overall mass-transfer coefficients and the corresponding flow rates are given in Table 1. Good agreement was observed with values given by Wendt et al, 1971 (where they used the notation Pobs for overall mass transfer coefficients). During the experiments the same flow rates were used on both sides of the membrane, and consequently Equation (1) (Malone and Anderson, 1977) becomes:…”

“…The permeability of Cuprophan PT-150 to NaCl at 37OC was found to be 1.51 x cm s-l. This value is 50% higher than that given by Wendt et al (1971) even after temperature correction (see Colton et al, 1971). This difference could be attributed to the considerable permeability variation between batches of Cuprophane PT-150 membranes (Hsu et al, 1976).…”

“…In previous analyses (Wendt et al, 1971 ;Malone and Anderson, 1977), boundary-layer Sherwood correlations for membrane operations were based on data obtained from batch-type dialyzers where the hydrodynamic conditions were altered by some kind of stirring effect. Another approach used the simulation of one-half of a diaphragm diffusion cell (Colton and Smith, 1972).…”

Starch-based films. Preliminary diffusion evaluation

“…The maximum available volume in each compartment was 46 cm3, and the area of exposed film, measured across contact with the large O-ring (100 mm diameter), was 78.5 cm2. Wendt et al (1971) found that the entire measured area of the membrane should be used to calculate observed permeabilities (P") even though the cell is only partly filled. Apparently, the diffusion process continues due to a thin film of solution being carried over the arc above the solution during rotation of the cell.…”

“…When a strong alkali, such as sodium hydroxide, was used in place of ammonia, we found the films to be much more transparent and quite permeable to small molecules. Permeability characteristics of the films were measured with a rotating dialysis cell prepared as described by Regan et al (1968) and Wendt et al (1971).…”