Im. Wienk et al., CRITICAL FACTORS IN THE DETERMINATION OF THE PORE-SIZE DISTRIBUTION OF ULTRAFILTRATION MEMBRANES USING THE LIQUID DISPLACEMENT METHOD, Separation science and technology, 29(11), 1994, pp. 1433-1440
The pore size distribution of ultrafiltration membranes can be determi
ned using the liquid displacement method developed by Munari and cowor
kers, However, when this technique is employed, several phenomena have
to be taken into consideration in order to avoid erroneous results. I
n this paper three phenomena are discussed. 1) During the measurement
the liquid flow is increased stepwise, resulting in pressure instabili
ties at the membrane surface. 2) The membrane permeability may be depe
ndent on the pressure and has to be determined at several pressures. 3
) Successive measurements of the same module show large differences be
tween the first run and following runs. Traces of glycerol, incomplete
pore filling, or long-term swelling are thought to be responsible for
erroneous results in the first run.