QUANTIFICATION OF FUNCTIONAL GROUPS IN THE ACTIVE LAYER OF HIGH PRESSURE MEMBRANES

摘要

The performance of nanofiltration (NF) and reverse osmosis (RO) membranes is closely related to membrane charge, which is the result of positive and negative functional groups (FGs) present in the membrane active layer [Petersen, 1993]. The net membrane charge relates directly to the rejection of charged species by the electric exclusion mechanism [Szymczyk, A. and Fievet, P., 2005], whereas FGs’ density is a result of the incomplete cross-linking of the membrane active layer polymer and thus relates to membrane-solute interaction. Detection of membrane surface FGs and confirmation of different group functionality at opposite sides of interfacially-polymerized polyamide films by means of contact angle titration methods has been reported [Wamser and Gilbert, 1992]. Net membrane charge has been traditionally studied via streaming potential analysis [Childress and Elimelech, 2000] and tangential streaming potential analysis [Szymczyk and Fievet, 2005]. Functional groups density, however, has remained elusive to quantification.