AWWA MTC69660

AWWA MTC69660 Depth Heterogeneity of Elemental Composition, Concentration of Functional Groups and Degree of Crosslinking in the Active Layers of Reverse Osmosis and Nanofiltration Membranes
Conference Proceeding by American Water Works Association, 11/01/2009

Coronell, Orlando; Gonzalez, Mari; Marinas, Benito J.; Cahill, David G.

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This research studied the depth heterogeneity of the elemental composition, concentration ofionized functional groups and degree of polymer cross-linking in the active layer of the ESNAnanofiltration (NF) and FT30 reverse osmosis (RO) membranes. The study also examined the elementalcomposition 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 usingthe ion-probing procedure reported in previous studies, and analyzing the preparedsamples using RBS, XPS and time-of-flight secondary ion-mass spectrometry (TOF-SIMS).Results show that the concentration of carboxylic groups and degree of polymercrosslinking in the active layer of the ESNA and FT30 membranes are higher near the topsurface than in the bulk of the active layer. In contrast, amine groups were found to bepreferentially located in the bottom ~ 100 nm of the FT30 active layer. Includes 21 references, table.