Insight into the separation mechanisms of MXene@PSS nanochannels for high-efficiency lithium extraction

MM Ge and DQ Wang and CL Wei and SJ Liu and LZ Meng and XM Liu and TM Fang, SEPARATION AND PURIFICATION TECHNOLOGY, 363, 132082 (2025).

DOI: 10.1016/j.seppur.2025.132082

In recent years, the application of membrane separation technology for recovering lithium from lithium-rich salt lake brine has become increasingly significant for the sustainable utilization of resources. In this work, a poly (sodium 4-styrene sulfonate) (PSS) chain polymer was incorporated into the two-dimensional material MXene layer to prepare a composite membrane for Li+/Mg2+ separation, which was analyzed for the through molecular dynamics (MD) simulation. The addition of PSS notably enhanced the Li+/Mg2+ selectivity of the membrane, increasing it from 1.7 to 8.9. Furthermore, we explored the transport differences of Li+ and Mg2+ in the MX@PSS channel by examining the two stages of ion transport process. The results reveal that the high rejection rate of the MX@PSS membrane towards Mg2+, driven by the synergistic effects of size and electrostatic interactions, contributes to its superior selectivity. Finally, the mechanism affecting the asymmetric structure on the separation properties of MX@PSS nanochannels was investigated. A high Li+ flux was obtained with MX@PSS(14 < 16), which further improves the separation performance of the composite membrane. This study elucidates the rapid transport mechanism of Li+ in MX@PSS, providing viable strategies and solid theoretical support for the design of highly selective Li+/Mg2+ separation membranes.

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