Modification Mechanism of Polyamide Reverse Osmosis Membrane by Persulfate: Roles of Hydroxyl and Sulfate Radicals.
Environ Sci Technol
; 56(12): 8864-8874, 2022 06 21.
Article
em En
| MEDLINE
| ID: mdl-35622994
ABSTRACT
Oxidative modification is a facile method to improve the desalination performance of thin-film composite membranes. In this study, we comparatively investigated the modification mechanisms induced by sulfate radical (SO4â¢â¯-) and hydroxyl radical (HOâ¢) for polyamide reverse osmosis (RO) membrane. The SO4â¢â¯-- and HOâ¢-based membrane modifications were manipulated by simply adjusting the pH of the thermal-activated persulfate solution. Although both of them improved the water permeability of the RO membrane under certain conditions, the SO4â¢â¯--modified membrane notably prevailed over the HOâ¢-modified one due to higher permeability, more consistent salt rejection rates over wide pH and salinity ranges, and better stability when exposed to high doses of chlorine. The differences of the membranes modified by the two radical species probably can be related to their distinct surface properties in terms of morphology, hydrophilicity, surface charge, and chemical composition. Further identification of the transformation products of a model polyamide monomer using high-resolution mass spectrometry demonstrated that SO4â¢â¯- initiated polymerization reactions and produced hydroquinone/benzoquinone and polyaromatic structures; whereas the amide group of the monomer was degraded by HOâ¢, generating hydroxyl, carboxyl, and nitro groups. The results will enlighten effective ways for practical modification of polyamide RO membranes to improve desalination performances and the development of sustainable oxidation-combined membrane processes.
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01-internacional
Base de dados:
MEDLINE
Assunto principal:
Radical Hidroxila
/
Nylons
Idioma:
En
Ano de publicação:
2022
Tipo de documento:
Article