PERVAPORATION MULTILAYER MEMBRANES BASED ON POLYELECTROLYTE COMPLEXES OF CHITOSAN AND ANIONIC POLYSACCHARIDES

摘要

Pervaporation has gained wide acceptance as a membrane separation method, and it is recognized as the most adaptable technique for the separation of water-organic mixtures. Several studies have demonstrated the greater effectiveness of hydrophilic pervaporation for membranes prepared from polyelectrolyte complexes (PEC) than from individual polymers [1]. However, the role of PEC in the separation process, and the mechanism of selective transport of polar multiple-charged ions through this type of membrane remain to be established. Most authors maintain that the unique properties of PEC reflect the existence of a specific hydrophilic-hydrophobic balance that can be easily changed by varying the composition of the complexes and the conditions of their preparation. The separation characteristics of multilayer PEC membranes formed by combining layers of polymeric electrolytes depend largely on the strength of the interactions between the macrocounterions. This interaction can change the structure of the film towards increasing order. This factor of interpolymer interaction is believed to prevail over other "structural" factors, such as the degree of crosslinking, the flexibility of the backbone, the presence of aromatic fragments, etc. Thus, obtaining regular non-defect layers of interpolymer complexes with good separating capability is considered possible only when using polyelectrolytes that have a high charge density.