Thermodynamic factors in partitioning and rejection of organic compounds by polyamide composite membranes

Adi Ben-David, Yoram Oren, Viatcheslav Freger

Research output: Contribution to journalArticlepeer-review

37 Scopus citations


The paper analyzes the mechanism of partitioning and rejection of organic solutes by polyamide membranes for reverse osmosis and nanofiltration. The partitioning of homologous series of alcohols and polyols, in which polarity changes with size in opposite ways, was measured using attenuated total reflection IR spectroscopy. The results show that the partitioning of polyols monotonously decreases with size, whereas for alcohols it is not monotonous and slightly decreases for small C1-C3 alcohols followed by a sharp increase for larger alcohols. These results may be explained by assuming a heterogeneous structure of polyamide comprising a hydrophobic polyamide matrix and a polar internal aqueous phase. The partitioning data could consistently explain the results of rejection in standard filtration experiments. They clearly demonstrate that high/low partitioning may play a significant role in achieving a low/high rejection of organics. In particular, this points to the need to account for the partitioning effect while using molecular probes such as polyols or sugars for estimating the effective "pore" size or molecular weight cutoff of a membrane and for choosing/developing organic-rejecting membranes.

Original languageEnglish
Pages (from-to)7023-7028
Number of pages6
JournalEnvironmental Science & Technology
Issue number22
StatePublished - 15 Nov 2006

ASJC Scopus subject areas

  • Chemistry (all)
  • Environmental Chemistry


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