THE SCIENCE OF REVERSE OSMOSIS -MECHANISMS, MEMBRANES, TRANSPORT AND APPLICATIONS

Abstract

A view of the science of reverse osmosis on the basis of the preferential sorption-capillary flow mechanism is presented. Preferential sorption at the membrane-solution interface is a function of solute-solvent-membrane material interactions arising from polar-, steric-, nonpolar-, and/or ionic-character of each one of the above components. Quantitative parameters for characterizing solutes and membrane materials at aqueous solution-membrane interfaces have been generated. Basic transport equations suitable for membrane specification and system analysis, and applicable for all membrane materials and membranes at all levels of solute separations have been developed for reverse osmosis systems involving aqueous solutions and preferential sorption of water at the membrane-solution interface. The polar, steric, and nonpolar parameters characterizing solutes have been built into the above transport equations through appropriate additional equations and correlations. As a result, it is now possible to predict the performance of a membrane for a large number of single and mixed solute aqueous feed solutions from only a single set of experimental reverse osmosis data for a reference NaCl-H2O feed solution. This is illustrated.