AWWA MTC69660

This research studied the depth heterogeneity of the elemental composition, concentration of ionized functional groups and degree of polymer cross-linking in the active layer of the ESNA nanofiltration (NF) and FT30 reverse osmosis (RO) membranes. The study also examined the elemental composition of the bulk of the active layers using Rutherford backscattering spectrometry (RBS), and the surface of the active layers using X-ray photoelectron spectroscopy (XPS). Finally, the concentration of functional groups was studied by preparing membrane samples using the ion-probing procedure reported in previous studies, and analyzing the prepared samples using RBS, XPS and time-of-flight secondary ion-mass spectrometry (TOF-SIMS). Results show that the concentration of carboxylic groups and degree of polymer crosslinking in the active layer of the ESNA and FT30 membranes are higher near the top surface than in the bulk of the active layer. In contrast, amine groups were found to be preferentially located in the bottom ~ 100 nm of the FT30 active layer. Includes 21 references, table.