Effects of polyether-polyamide block copolymer coating on performance and fouling of reverse osmosis membranes

Jennifer S. Louie, Ingo Pinnau, Isabelle Ciobanu, Kenneth P. Ishida, Alvin Ng, Martin Reinhard*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

257 Scopus citations


The effects of a water-permeable polymer coating on the performance and fouling of high-flux (ESPA1 and ESPA3) and low-flux (SWC4) polyamide reverse osmosis (RO) membranes were investigated. It was anticipated that the coating would create a smoother hydrophilic surface that would be less susceptible to fouling when challenged with a motor-oil/surfactant/water feed emulsion (used as a model foulant). AFM and FT-IR analyses confirm that a 1 wt.% polyether-polyamide (PEBAX® 1657) solution applied to ESPA and SWC4 membranes produces a continuous polymer coating layer and, thereby, provides smoother membrane surfaces. However, pure-water permeation data combined with a series-resistance model analysis reveal that the coating does not only cover the surface of the polyamide membrane, but also penetrates into its porous ridge-and-valley structure. During a long-term (106-day) fouling test with an oil/surfactant/water emulsion, the rate of flux decline was slower for coated than for uncoated membranes. This improvement in fouling resistance compensated for the decrease in permeate flux for SWC4 over a period of approximately 40 days. However, the coating material is believed to penetrate more deeply into the polyamide surface layer of the high flux, high surface area ESPA membranes relative to the low-flux SWC4, resulting in significant water flux reduction.

Original languageEnglish (US)
Pages (from-to)762-770
Number of pages9
JournalJournal of Membrane Science
Issue number1-2
StatePublished - Sep 1 2006
Externally publishedYes


  • Coating
  • Fouling
  • Polyether-polyamide block copolymer
  • RO membranes
  • Surface modification

ASJC Scopus subject areas

  • Biochemistry
  • General Materials Science
  • Physical and Theoretical Chemistry
  • Filtration and Separation


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