Encircling Angstrom-Scale Channels with Three-Dimensional Network Charges for Enhancing Ion Separation.

Area of Science:

• Materials Science
• Chemical Engineering
• Nanotechnology

Background:

• Membrane-based ion separation is crucial for lithium extraction, wastewater treatment, and energy harvesting.
• Optimizing ion selectivity through charge interactions is key for efficient membrane performance.

Purpose of the Study:

• To investigate the ion separation selectivity of angstrom-scale channels created by a unique 3D network charges-encirclement structure.
• To explore the potential of this novel membrane design for advanced ion separation applications.

Main Methods:

• Fabrication of angstrom-scale channels via swift heavy ion bombardment of polyimide films followed by UV treatment.
• Characterization of channel dimensions (∼7 Å) and ion selectivity (K+/Mg2+ up to 1.2 × 10^5).
• Utilizing characterizations and simulations to understand the role of 3D charge configuration in ion transport.

Main Results:

• Achieved remarkable K+/Mg2+ selectivity (1.2 × 10^5 in single-salt, 1.8 × 10^3 in binary-salt solutions).
• Demonstrated superior performance compared to most state-of-the-art ion separation channels.
• Identified that the 3D charge configuration promotes monovalent ion transport and hinders multivalent ions.

Conclusions:

• 3D network charges-encirclement in angstrom-scale channels provides exceptional ion separation selectivity.
• This approach offers a new paradigm for designing high-precision ion separation membranes.
• Findings pave the way for next-generation membranes in critical separation processes.