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Merging Ion Concentration Polarization between Juxtaposed Ion Exchange Membranes to Block the Propagation of the Polarization Zone
Published on: February 23, 2017
Synergistic Interfacial Design of Cation Exchange Membranes via Sequential Electro-Assembly for High-Efficiency
Zhibo Zhang1,2, Geting Xu1,2, Yangbo Qiu3
1College of Chemical Engineering, Zhejiang University of Technology, Hangzhou 310014, China.
Abstract:
The industrial application of modified ion-exchange membranes is limited by complex, discontinuous ex-situ processes. This study introduces an in-situ electro-assembly strategy that enables the direct fabrication of a selective layer within an electrodialysis stack without disassembly. By utilizing a programmed current reversal to orchestrate the sequential deposition of polyethyleneimine (PEI), glutaraldehyde cross-linking, and polystyrene sulfonate (PSS) adsorption, we achieve meticulous interfacial engineering on a commercial cation exchange membrane. Comprehensive characterization confirms the successful construction of a hydrophilic, charge-tuned multilayer, which enhances ion transport kinetics and raises the limiting current density. This method culminates in a membrane with an exceptional Li+/Mg2+ selectivity of 107.9 and robust stability, retaining a significant selectivity of 47 over 10 cycles in real salt lake brine. This synergistic integration of operational simplicity, interfacial precision, and superior performance establishes a transformative and scalable platform for manufacturing high-performance membranes for selective ion separation from complex brine sources.
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