Studies of the pore space of the UPM-K, UAM-50, UAM-100 composite ultrafiltration membrane

Abstract

The development of methods for assessing the distribution of pores by radii (or diameters) and studying the microstructure of the surface of a membrane partition is an urgent task. The authors of the paper carried out experimental studies of the pore diameter distribution for the UPM-K ultrafiltration membrane, determined the porosity and hydrodynamic permeability of the UAM-50, UAM-100 membranes. The analysis of the experimental results showed that the UPM-K ultrafiltration membrane had an average pore diameter of 54 nm. The UAM-50 and UAM-100 membranes were characterized by an asymmetric structure (an active layer (dense) and a porous substrate), while the pores were 2.5–40 and 10–40 nm in size, respectively. The experiments on the study of the hydrodynamic permeability of UAM-50, UAM-100 ultrafiltration membranes when separating a solution of sodium lauryl sulfate showed that the kinetic response curves of the “membrane-solution” system were conventionally divided into two stages. The first stage of the process was faster and lasted only a few minutes. After 7.8 and 13.05 min, the hydrodynamic permeability decreased by ~ 27 %, 7 %, which was due to structural changes in the cellulose acetate layer under the action of mechanical load (transmembrane pressure). The second stage was slower – with a duration of ~ 33 and 60 min and a decrease in hydrodynamic permeability by 41 % and 11 %. Based on the analysis of the approximating function, the rate constants of the membrane separation of solutions and the empirical coefficients of the equation are found.