Hypochlorite treatment of polyamide membrane for improved reverse osmosis performance

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DOIResolve DOI: http://doi.org/10.12989/mwt.2013.4.1.069
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TypeArticle
Journal titleMembrane Water Treatment
ISSN2005-8624
Volume4
Issue1
Pages6981; # of pages: 13
SubjectChlorinating species; Hypochlorite treatment; Membrane chemistry; N-chlorination; Salt rejections; Alkalinity; Chlorination; Chlorine; Hydrolysis; pH; Polyamides; Reverse osmosis; Membranes
AbstractThe pH-dependent inter-conversion of the three free chlorine species (Cl2, HOCl, OCl-) present in the aqueous hypochlorite solution was theoretically investigated. Each species was found overwhelmingly present in a characteristic pH range. Hypochlorite treatment of the polyamide membrane was carried out over these pH ranges and various membrane responses were observed. As pH is less than 8, membrane tends to be N-chlorinated by Cl2 and HOCl, and N-chlorinated membrane showed reduced water permeance and salt rejection. As pH rises to 10-12, OCl appears to be the dominating chlorine species. Membrane hydrolysis was found to well interpret the improved water permeance and salt rejection. When the pH is between 8-10, both N-chlorination and hydrolysis contribute to the response of the membrane, and the treated membrane showed improved salt rejection but reduced water permeation. Excessive hydrolysis occurred while the membrane was treated at pH 13 for the much stronger alkalinity.
Publication date
LanguageEnglish
AffiliationNational Research Council Canada (NRC-CNRC); Energy, Mining and Environment (EME-EME)
Peer reviewedYes
NPARC number21269339
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Record identifierbbf27c9f-434e-4030-b494-e415882e46a4
Record created2013-12-12
Record modified2016-05-09
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