REJECTION OF CONCENTRATED ELECTROLYTES BY REVERSE-OSMOSIS MEMBRANES

An experimental study has been made of the permeability and selectivit y of Akvapor composite reverse-osmosis membranes in the filtration of concentrated solutions of NaCl and CaCl2. It is shown that the nonline arity of the filtration characteristics of the membrane is related to the influence of capillary-osmotic counterflow. The lowering of the dy namic osmotic backpressure makes it possible to separate solutions wit h a selectivity coefficient phi = 0. 25-0.3, with relatively low press ure drops across the membrane (2-3 MPa). Structural characteristics of the substrate and the selective layer of the membrane have been obta ined.