Ion transport characteristics in nanofiltration membranes: Measurements and mechanisms

Noeon Park, Jaeweon Cho, Seungkwan Hong, Sangyoup Lee

Research output: Contribution to journalArticlepeer-review

15 Citations (Scopus)


Ion transport characteristics during nanofiltration (NF) were investigated by measuring effective osmotic pressure and diffusivity experimentally. Effective osmotic pressure and diffusivity were measured through lab-scale transport and diffusion tests. First, it was shown that the water flux across NF membranes decreased dramatically with increasing ionic strength because of the noticeable increase in effective osmotic pressure. Second, the results from transport experiments showed that the ion selectivity values, which were derived from the thermodynamic model, decreased with increasing ionic strength. Third, by analysing the data of measured osmotic pressure and diffusivity, it was demonstrated that the former and the latter increased and decreased, respectively, as ionic strength increased. The experimentally determined osmotic pressure across NF membranes was much lower than that calculated theoretically. At best, around 5% or less of the theoretical osmotic pressure was obtained under the experimental conditions investigated. The effective osmotic pressure and ion rejection decreased in the presence of nano-colloids. The influence of nano-colloids on ionic transport was found to be dependent on the concentration and size of the nano-colloids. Therefore, ion transport characteristics across NF membranes can be determined practically by measuring effective osmotic pressure and diffusivity as these reflect both feed water and membrane properties.

Original languageEnglish
Pages (from-to)179-190
Number of pages12
JournalJournal of Water Supply: Research and Technology - AQUA
Issue number2-3
Publication statusPublished - 2010


  • Effective diffusivity
  • Effective osmotic pressure
  • Ion transport characteristics
  • Nano-colloids
  • Nanofiltration

ASJC Scopus subject areas

  • Environmental Engineering
  • Water Science and Technology
  • Health, Toxicology and Mutagenesis


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