Steady-State Sieving across Membranes

Science  21 May 1971:
Vol. 172, Issue 3985, pp. 858-859
DOI: 10.1126/science.172.3985.858


The constraint of steady-state operation for sieving or ultrafiltration across membranes greatly restricts possible theoretical mechanisms. Effective sieving in the steady state requires the coexistence of a removal mechanism with the rejection mechanism. These points are illustrated without elaborate mathematics by a model of membranes in a series array with intervening compartments. This model also shows that in certain regimes the structure of the first membrane alone determines the overall sieving characteristics of the array.