The comparison of theoretical retention curves related to the sieving
mechanism of Ferry and to the distribution of membrane pores by size (
PSD) with experimental curves of polymeric ultrafiltration (UF) membra
nes and of membranes obtained by using the surface layers of bacteria
cell envelopes was carried out. It follows from this comparison that t
he separation mechanism in ultrafiltration has essentially a sharper c
haracter than when it is determined by Ferry's equation. It also follo
ws that the determining factor in the resolving power of ultrafiltrati
on is the structure of the UF membranes and especially the PSD width.
Therefore, one may hope that the improvement of UF membrane structure
will greatly increase the resolving power of ultrafiltration making it
comparable to that of gel permeation chromatography.