TRANSPORT AND SEPARATION OF ORGANIC MACROMOLECULES IN ULTRAFILTRATION PROCESSES

The membrane transport and separation characteristics of natural humic macromolecules and a model polyelectrolyte, poly(styrene sulfonate), in ultrafiltration systems employing hydrophilic, neutral, cellulosic-type membranes were studied. The application of a permeation model based on membrane flux equation was systematically validated for charged, random-coil polymers. It was possible to characterize transport behavior of various solute/membrane combinations by a single membrane permeation factor, which was found to depend strongly on solution ionic strength, but to be relatively independent of the ultrafiltration operating mode. It was determined that under certain conditions of solution ionic strength, molecular weight cutoff specifications provided by manufacturers may significantly exceed actual values for random-coil polymers. The findings of the study are considered in the several contexts of methodologies for assessing macromolecule coiling characteristics, macromolecule sample fractionation, and molecular weight determinations for natural organic matter.