Characterization of multilayer nanofiltration membranes using positron annihilation spectroscopy

• Published in: Journal of membrane science Vol. 343; no. 1; pp. 147 - 156
• Main Authors: Tung, Kuo-Lun, Jean, Yan-Ching, Nanda, Dipankar, Lee, Kueir-Rarn, Hung, Wei-Song, Lo, Chia-Hao, Lai, Juin-Yih
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.11.2009
• Subjects: Membrane characterization; Nanofiltration; Pore size distribution; Positron annihilation spectroscopy; Slow positron beam; Nanofiltration; Membrane characterization; Slow positron beam; Pore size distribution; Positron annihilation spectroscopy
• ISSN: 0376-7388; 1873-3123
• DOI: 10.1016/j.memsci.2009.07.020

Positron annihilation spectroscopy (PAS) coupled with a slow positron beam was used to characterize in situ the layer structure and depth profile of the cavity size in thin film composite (TFC) polyamide nanofiltration (NF) membranes prepared by the interfacial polymerization method. Two techniques, using PAS coupled with a slow positron beam of Doppler broadening energy spectra (DBES) and positron annihilation lifetime spectroscopy (PALS) designed to reveal the layer structure and the cavity sizes contained in a multilayer thin film composite NF membrane, were assessed. To the best knowledge of the authors, a characterization of the depth profile of cavities in NF membranes using PAS coupled with a slow positron beam has never been reported. The membranes selected have a composite structure containing three layers: a selective polyamide layer, a transition layer, and a porous support prepared by the phase inversion technique. Furthermore, the cavity size distribution in the selective top layer plays an important role in determining the performance of the NF membranes.