用于盐湖提锂的聚酰胺复合纳滤膜制备及其性能研究

纳滤膜技术以其环境友好、装置集成度高和智能化控制等优势，在卤水锂资源绿色开发领域具有良好的应用前景。实验通过添加聚乙烯醇对纳滤膜功能层进行改性，考察了聚乙烯醇相对含量对纳滤膜性能的影响。结果表明，聚乙烯醇参与界面聚合反应，纳滤膜功能层O/N比增加，聚乙烯醇分子链间氢键作用降低纳滤膜表面粗糙度。羟基官能团的引入有效改善纳滤膜材料亲水效果，膜面羧基密度随聚乙烯醇相对添加量的增加逐渐增加。聚乙烯醇改性纳滤膜截留效果优异，纳滤膜对镁离子的截留率高于95%,锂离子截留率低于-44%,不可逆通量衰减指数低于15%。聚乙烯醇改性纳滤膜材料具有较好的镁锂分离选择效果及抗污染能力，为用于盐湖卤水镁锂分离国产化纳滤膜材料的开发提供新思路。

Preparation and properties of polyamide nanofiltration membrane based on lithium extraction from salt lake brine

Nanofiltration has received considerable attention in the extraction of lithium from salt lake brine for high flux, high device integration, and low environmental impact. A nanofiltration membrane was modified by polyvinyl alcohol to enhance the efficiency of antifouling and the selectivity performance of magnesium and lithium. The results show that the O/N ratio of nanofiltration membrane increases and the roughness decreases after the modification. The hydrophily of nanofiltration membrane enhances with the introduction of hydroxyl, and the strong hydrogen bonding inhibits the interfacial polymerization which increases the density carboxyl of nanofiltration membrane. The nanofiltration membranes have excellent separation and selectivity performance and the retention rate for magnesium is above 95% and that of lithium is less than -44%, and the decay coefficients of the irreversible flux are lower than 15% showing remarkable antifoulingSability. The preparation of nanofiltration membranes modified by polyvinyl alcohol provides support for the development of domestic membrane materials suitable for the separation of magnesium and lithium from salt lake brine.