纳滤膜在盐湖提锂领域的研究进展

Research progress on nanofiltration membranes in lithium extraction from salt lakes

中国锂(Li)资源消耗量占全球消耗量的40%,然而其产能仅满足工业需求的20%,80%的Li需要进口,研究新一代提Li技术迫在眉睫。纳滤(NF)膜具有选择性离子分离能力,在Mg^(2+)、Li^(+)的选择性分离中表现出突出的潜力。商用NF膜多荷负电,受Donnan效应和静电引力影响,其对正离子的分离能力有限。近年来的研究发现,荷正电NF膜可以有效分离具有相似水合物离子半径的Mg^(2+)和Li^(+)。该文介绍了NF膜中离子传输理论和选择性筛分机理,综述了商用NF膜在盐湖提Li领域的研究现状及不足,分析了荷正电NF膜的制备方式(包括胺单体的选取、纳米材料掺杂、引入中间层及表面接枝等)对提升Mg^(2+)、Li^(+)的选择性分离性能的影响规律。最后,总结了荷正电NF膜在实际工程应用中的挑战和前景。

The consumption of lithium resources in China accounts for 40% of the global consumption,while its production capacity can only meet 20% of the industrial demand,with 80%imported.Therefore,development of new lithium extraction technology is of urgency and significance.Nanofiltration (NF)membrane,with selective ion separation capacity,exhibits outstanding potential in the selective separation of Mg^(2+)and Li^(+).Commercial NF membrane is usually negatively charged,and its separation ability for positively charged ions is limited due to Donnan effect and electrostatic attraction.In recent years,it has been found that positively charged NF membrane shows effective separation on Mg^(2+) and Li^(+) with similar hydrate ion radii.In this review,the ion transport theory and selective screening mechanism of NF membrane were introduced,followed by summarization on the status quo and disadvantages of commercial NF membrane in the field of lithium extraction from salt lakes.The influence of preparation methods of positively charged NF membrane (including the selection of amine monomer,doping of nano-materials,introduction of interlayer and surface grafting,etc.) on improvement in the selective separation performance of Mg^(2+)and Li^(+) was then analyzed.Finally,the challenges and prospects of positively charged NF membrane in practical engineering applications were discussed.