Ion Separation by Hyperfìltration Through Charged Membranes. II. Separation Performance of Collodion-Polybase Membranes

Appreciable separations between divalent or trivalent salt solutions and corresponding mineral acids can be achieved by hyperfìltration of mixtures through loose ion-exchange merhbranes. Porous charged membranes allowing high rates of volume flow were prepared by cross-linking of polyamines into a porous collodion matrix or by reaction of polyamines with a chemically modified collodion matrix. Hyperfìltration of salt-acid mixtures through these membranes gave enrichment of acid in the product and concentration of salt in the feed. The gap between rejections was larger in hyperfìltration of mixtures than in hyperfìltration of separate solutions.