| Abstract: | The mechanisms by which cellulose acetate membranes can be effective in removing salt from aqueous solution have been considered in relation to available experimental data. It is proposed that diffusive flow is involved, through a pore-free layer in the membrane, and that solute rejection occurs as a result of the high pressures used, and of the fact that the solute is present at relatively low concentration. The effect of pressure on the activity of a component present at low concentration is small, and consequently the flow of solvent is increased to a greater extent at high pressures than is the flow of solute. Rejection thus approaches 100% asymptotically, as the pressure on the system is increased. |
