Liquid-phase water isotope separation using graphene-oxide membranes

Karin Ching, Andy Baker, Ryoji Tanaka, Tingwen Zhao, Zhen Su, Rodney S. Ruoff, Chuan Zhao, Xianjue Chen

Research output: Contribution to journalArticlepeer-review

Abstract

We report pressure-driven liquid-phase isotope separation (dead-end filtration) to enrich D and 18O in natural water using graphene oxide (G-O) and UV-reduced graphene oxide (UV-rG-O) membranes. The isotope diffusivity (molecular diffusion and adsorption separation) was found to be responsible for isotope separation. Adsorption separation is the dominant mechanism for improvements in D and 18O enrichment via increased G-O loading that leads to the increased number of adsorption sites (epoxy and hydroxyl groups on G-O), and higher degrees of reduction of G-O that result in the narrowing of the nanochannels which decreases the portion of water molecules experiencing molecular diffusion. The best performing membrane was “UV-rG-O” made by exposing a G-O membrane to 24 h UV irradiation from one side, showing enrichment of D of 0.5% for D/H and 18O of 0.08% for 18O/16O in a single-stage experiment, without contribution from the vapor pressure isotope effect. This work improves the understanding of the mechanisms for graphene-based membrane separation of D and 18O enriched water.

Original languageEnglish
Pages (from-to)344-354
Number of pages11
JournalCarbon
Volume186
DOIs
Publication statusPublished - Jan 2022

Keywords

  • Diffusion
  • Filtration
  • Graphene oxide
  • Isotope effect
  • Membranes
  • Water isotopes

ASJC Scopus subject areas

  • Chemistry(all)
  • Materials Science(all)

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