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Title: Degradation of polyamide nanofiltration and reverse osmosis membranes by hypochlorite
Authors: Tang, Chuyang Y.
Reinhard, Martin
Leckie, James O.
Do, Van Thanh
Keywords: DRNTU::Engineering::Civil engineering
DRNTU::Engineering::Environmental engineering
Issue Date: 2012
Source: Do, V. T., Tang, C. Y., Reinhard, M., & Leckie, J. O. (2012). Degradation of polyamide nanofiltration and reverse osmosis membranes by hypochlorite. Environmental science & technology, 46(2), 852-859.
Series/Report no.: Environmental science & technology
Abstract: The degradation of polyamide (PA) nanofiltration and reverse osmosis membranes by chlorine needs to be understood in order to develop chlorine-resistant membranes. Coated and uncoated fully aromatic (FA) and piperazine (PIP) semi-aromatic PA membranes were treated with hypochlorite solution and analyzed by X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FTIR). XPS results showed that in chlorine treated FA PA membranes the ratio of bound chlorine to surface nitrogen was 1:1 whereas it was only 1:6 in the case of PIP PA membranes. Surface oxygen of uncoated FA and PIP membranes increased with increasing hypochlorite concentration whereas it decreased for coated FA membranes. High resolution XPS data support that chlorination increased the number of carboxylic groups on the PA surface, which appear to form by hydrolysis of the amide bonds (C(O)–N). FTIR data indicated the disappearance of the amide II band (1541 cm–1) and aromatic amide peak (1609 cm–1) in both coated and uncoated chlorinated FA membranes, consistent with the N-chlorination suggested by the XPS results. Furthermore, the surface charge of chlorinated membranes at low pH (<6) became negative, consistent with amide-nitrogen chlorination. Chlorination appeared to both increase and decrease membrane hydrophobicity depending on chlorination exposure conditions, which implied that N-chlorination and hydrolysis may be competing processes. The effects of property changes on the membrane performance were also observed for NF90, BW30, and NF270 membranes.
DOI: 10.1021/es203090y
Fulltext Permission: none
Fulltext Availability: No Fulltext
Appears in Collections:CEE Journal Articles

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