Synergistic Interfacial Design of Cation Exchange Membranes via Sequential Electro-Assembly for High-Efficiency...

Area of Science:

• Materials Science
• Electrochemistry
• Chemical Engineering

Background:

• Industrial use of modified ion-exchange membranes is hindered by complex, multi-step ex-situ fabrication processes.
• Existing methods often lack precision in interfacial engineering, limiting membrane performance and scalability.

Purpose of the Study:

• To develop an in-situ electro-assembly strategy for fabricating selective ion-exchange membranes directly within an electrodialysis stack.
• To engineer a hydrophilic, charge-tuned multilayer on a commercial cation exchange membrane for enhanced ion separation.

Main Methods:

• An in-situ electro-assembly strategy using programmed current reversal for sequential deposition of polyethyleneimine (PEI), glutaraldehyde, and polystyrene sulfonate (PSS).
• Fabrication of a selective layer directly onto a cation exchange membrane without stack disassembly.
• Comprehensive characterization of the membrane's structure, hydrophilicity, and ion transport properties.

Main Results:

• Successful construction of a hydrophilic, charge-tuned multilayer membrane with enhanced ion transport kinetics and increased limiting current density.
• Achieved exceptional Li+/Mg2+ selectivity of 107.9.
• Demonstrated robust stability, maintaining a selectivity of 47 over 10 cycles in real salt lake brine.

Conclusions:

• The in-situ electro-assembly method offers operational simplicity, interfacial precision, and superior performance for membrane manufacturing.
• This transformative and scalable platform is ideal for producing high-performance membranes for selective ion separation from complex brines.
• The developed membranes show significant potential for industrial applications in resource recovery from saline sources.