Water and ions transport mechanism in hyperfiltration with symmetric cellulose acetate membranes

Hyperfiltration is carried out under reverse osmotic conditions by the application of mechanical energy to force the solvent from higher to lower concentration of solute across semipermeable membranes. In the present investigation, experimental work has been performed to measure the water and inorganic cation transport fluxes across cellulose acetate homogeneous hyperfiltration membranes. The osmosis, reverse osmosis, kinetic conductance and membrane potential measurements have helped to determine the hydrodynamic permeability coefficient (L-p), solute permeability coefficient (omega) and reflection coefficient (sigma) for KCl, NaCl, CaCl2 and LaCl3 salts at varied temperatures. Kinetic conductance augmented with membrane potential measurement data has been used to determine molar distribution coefficient and ion exchange capacity, the ionic mobilities and diffusion coefficients of the ions using the theoretical equations relating various functions. The studies have proved useful in understanding the mechanism of water and ions transport through the given polymeric membranes. In the present paper solution diffusion theory has been considered and the amendments to be introduced in the related equations are explained. (C) 2002 Elsevier Science B.V. All rights reserved.