Re. Baltus, CHARACTERIZATION OF THE PORE AREA DISTRIBUTION IN POROUS MEMBRANES USING TRANSPORT MEASUREMENTS, Journal of membrane science, 123(2), 1997, pp. 165-184
An approach originally proposed by Mason and coworkers has been applie
d to model porous membranes to show that transport measurements with s
mall and large solutes can be used to distinguish between porous membr
anes with the same average pore size but different pore size distribut
ions. In addition, it is shown that such measurements can be used to a
ccount for membrane heteroporosity when predicting the sieving charact
eristics of a membrane. This is done by applying moment theory to resu
lts from flux measurements for a small solute at Pe approximate to 1 o
r to results from measurements of the reflection coefficient for a lar
ge solute at infinite Pe. No a priori assumptions about the nature of
the distribution of pore areas are necessary. In this paper, the resul
ts from calculations performed with three different model membranes wi
th log-normal pore size distributions are reported. These results show
that one can begin to distinguish between membranes by measuring the
hydraulic and diffusive permeability and performing at least one addit
ional flux measurement - with either a small, non-hindered solute at P
e approximate to 1 or a large solute at infinite Pe. Results also show
that a fairly narrow window can be placed on the sieving curve for a
heteroporous membrane without performing any sieving measurements. Thi
s is an interesting and encouraging result because it means that many
of the problems that arise from measuring and interpreting pore size d
istributions using more traditional techniques can be avoided by using
small solute flux measurements to predict the separation characterist
ics of many porous membranes.