Reverse osmosis rejection by hydrous inorganic precipitate–cellulose composite membrane

Abstract

AbstractComposit membranes were prepared by impregnating hydrous inorganic precipites (Fe and Cr oxides, nickel chromate or molybdate) into a cellulose acetate membrane which serves as a support. In these membranes, the hydrous iron oxide composite membrane showed high reverse osmosis properties. The permeability of the composite membrane did not decline with time, and the rejection of organic solute was not appreciably affected by impregnation. However, the rejection of electrolyte increased with impregnation. The measurements of membrane potential revealed that salt rejection is primarily attributable to the effect of membrane charge, i.e., to ion exclusion effect. In electrolyte solutions of 1:1 and 2:1, the membrane was anion selective; on the other hand, in electrolyte solution of 1:2, the membrane was cation selective. These results are characteristic of impregnated hydrous metal oxide.