Facile Modification of Reverse Osmosis Membranes by Surfactant-Assisted Acrylate Grafting for Enhanced Selectivity

Katie Baransi-Karkaby, Maria Bass, Stanislav Levchenko, Shahar Eitan, Viatcheslav Freger

Research output: Contribution to journalArticlepeer-review


The top polyamide layer of composite reverse osmosis (RO) membranes has a fascinatingly complex structure, yet nanoscale nonuniformities inherently present in polyamide layer may reduce selectivity, e.g., for boron rejection. This study examines improving selectivity by in situ "caulking" such nonuniformities using concentration polarization-enhanced graft-polymerization with a surfactant added to the reactive solution. The surfactant appears to enhance both polarization (via monomer solubilization in surfactant micelles) and adherence of graft-polymer to the membrane surface, which facilitates grafting and reduces monomer consumption. The effect of surfactant was particularly notable for a hydrophobic monomer glycidyl methacrylate combined with a nonionic surfactant Triton X-100. With Triton added at an optimal level, close to critical micellization concentration (CMC), monomer gets solubilized and highly concentrated within micelles, which results in a significantly increased degree of grafting and uniformity of the coating compared to a procedure with no surfactant added. Notably, no improvement was obtained for an anionic surfactant SDS or the cationic surfactant DTAB, in which cases the high CMC of surfactant precludes high monomer concentration within micelles. The modification procedure was also up-scalable to membranes elements and resulted in elements with permeability comparable to commercial brackish water RO elements with superior boric acid rejection.

Original languageEnglish
Pages (from-to)2347-2354
Number of pages8
JournalEnvironmental Science and Technology
Issue number4
StatePublished - 21 Feb 2017
Externally publishedYes

Bibliographical note

Publisher Copyright:
© 2017 American Chemical Society.

ASJC Scopus subject areas

  • General Chemistry
  • Environmental Chemistry


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