Application of positron annihilation technique to reverse osmosis membranematerials

Positron annihilation lifetime spectroscopy has been adopted as a new appro ach for studying vacancies of reverse osmosis membrane materials composed o f cellulose acetate films and aromatic polyamide resins. The intensity of t he ortho-positronium (o-Ps) lifetime increased with the amount of vacancies determined using N-2 isotherm at -195 degrees C. Changes of vacancy profil es induced by heat treatment in the cellulose acetate films were detected u sing o-Ps. It was found that the positron annihilation technique is applica ble to the study of vacancy profiles associated with salt selectivity in ty pical reverse osmosis membranes. (C) 2000 Elsevier Science Ltd. All rights reserved.