Kinetic barrier networks reveal rate limitations in ion-selective membranes

Ryan S. Kingsbury, Michael A. Baird, Junwei Zhang, Hetal D. Patel, Miranda J. Baran, Brett A. Helms, Eric M.V. Hoek

Research output: Contribution to journalArticlepeer-review

8 Scopus citations

Abstract

While polymer membranes are used to remove salts from environmental and industrial electrolytes, it remains a significant challenge to engineer them to isolate a single dissolved species from complex mixtures, which is important for lithium mining, battery and magnet recycling, and microelectronics. Underpinning this challenge has been a lack of understanding of rate-limiting mechanisms in selective ion transport. Here, we show that hydrated ions exhibit higher free energies of activation when crossing solution-membrane interfaces (i.e., partitioning) than when diffusing through polymers, which challenges historical assumptions embedded in widely used models of membrane performance. We further articulate a framework benchmarked with quantitative capabilities for predicting how functionality within polymer membranes or at their surfaces affects selectivity toward individual dissolved species.

Original languageEnglish (US)
Pages (from-to)2161-2183
Number of pages23
JournalMatter
Volume7
Issue number6
DOIs
StatePublished - Jun 5 2024
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • General Materials Science

Keywords

  • MAP 3: Understanding
  • desalination
  • electrodialysis
  • ion transport
  • lithium
  • membrane
  • membrane selectivity
  • polymers of intrinsic microporosity
  • separation
  • transition state theory

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