Ternary Heterostructure Membranes with Two-Dimensional Tunable Channels for Highly Selective Ion Separation

Area of Science:

• Materials Science
• Chemical Engineering
• Environmental Science

Background:

• Selective ion separation from brines is crucial for obtaining high-purity lithium, a vital nonrenewable resource.
• Conventional separation methods face significant challenges, necessitating the development of more efficient and rapid approaches.

Purpose of the Study:

• To present a novel graphene oxide (GO)-based ternary heterostructure membrane for selective ion separation.
• To demonstrate a unique design for tunable interlayer channels that precisely control ion passage based on hydration radius.

Main Methods:

• Fabrication of a GO-based ternary heterostructure membrane incorporating two-dimensional zeolitic imidazolate framework-8 (ZIF-8) and zinc alginate (ZA) polymers.
• Utilizing Zn2+-induced confinement synthesis in a two-dimensional space to create tunable interlayer channels.
• Modulating membrane layer spacing based on ion hydration radius for selective ion transport.

Main Results:

• The hybrid ionic intercalation membrane exhibited tunable layer spacing, facilitating rapid passage of smaller hydrated ions while hindering larger ones.
• Achieved remarkable selectivity with ion pair partitioning ratios: K+/Li+ = 20.9, Na+/K+ = 31.2, and Li+/Mg2+ = 9.5.
• The ZIF-8/GO heterostructure enhanced selectivity, while the ZA/GO heterostructure improved mechanical robustness and stability.

Conclusions:

• The developed GO-based ternary heterostructure membrane offers a promising solution for efficient and selective ion separation from brines.
• This advanced membrane design holds significant potential for lithium extraction and various other ion separation applications.
• The unique design provides precise control over ion transport, addressing limitations of existing separation technologies.