A mixed-charge polyelectrolyte complex nanofiltration membrane: Preparation, performance and stability

Michael Zelner, Philipp Jahn, Mathias Ulbricht, Viatcheslav Freger

Research output: Contribution to journalArticlepeer-review

12 Scopus citations


Ion selectivity of nanofiltration (NF) membranes is a critical factor in NF treatment of scaling-prone multi-ion effluents, such as wastewater. When removal of multivalent ions in such effluents is unnecessary or undesired, adjusting their rejection may mitigate scaling, in which case membranes combining oppositely charged electrolytes enable a tunable selectivity towards such ions. Here we report the fabrication of a new tunable and highly stable polyelectrolyte complex NF membrane prepared by successively coating an ultrafiltration membrane support with negatively charged Nafion and positively charged polyvinylamine (PVAm) layers. While Nafion thickness controls the membrane permeability, the second PVAm coating is critical for eliminating defects in the Nafion layer and readily tunes the membrane net charge and, hence, ion selectivity via PVAm concentration in the coating solution. In this manner, a membrane with good permeability, balanced charge, and, therefore, equal (“symmetric”) rejection of divalent anions and cations is obtained. The membrane performance is unaffected by exposure to 10% salt in water; such remarkable stability for a polyelectrolyte-based membrane makes it potentially attractive for the treatment of wastewater effluents and brackish water sources.

Original languageEnglish
Article number119579
JournalJournal of Membrane Science
StatePublished - 15 Oct 2021
Externally publishedYes


  • Divalent ion rejection
  • Mixed polyelectrolyte membrane
  • Nanofiltration
  • Scaling mitigation
  • Tertiary wastewater treatment
  • Wastewater desalination

ASJC Scopus subject areas

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


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