基于LDH中间层的纳滤膜及其镁锂分离性能  

Nanofiltration Membrane Based on LDH Intermediate Layer and Its Magnesium Lithium Separation Performance

作　　者：倪红旭 王乃鑫[1] 安全福 NI Hongxu;WANG Naixin;AN Quanfu(Faculty of Environment and Life,Beijing University of Technology,Beijing 100124,China)

机构地区：[1]北京工业大学环境与生命学部,北京100124

出　　处：《北京工业大学学报》2024年第2期187-194,共8页Journal of Beijing University of Technology

基　　金：国家自然科学基金资助项目(22178008,22125801)。

摘　　要：实现盐湖卤水中镁锂的分离成为盐湖提锂过程中面临的巨大挑战,开发具有高镁锂分离性能的纳滤膜成为亟待解决的关键问题。通过化学刻蚀法获得了多孔层状双金属氢氧化物(layered double hydroxide,LDH)纳米片,然后将其沉积在聚丙烯腈多孔膜表面作为中间层,在该中间层上通过聚乙烯亚胺与均苯三甲酰氯界面聚合形成聚酰胺分离层,最终获得表面荷正电的LDH/聚酰胺纳滤膜。LDH中间层不仅增强了膜表面的荷正电性,且诱导聚酰胺层形成咖啡环结构,提高了膜表面的粗糙度,因此同步提高了膜的选择性和渗透性。当分离镁锂比为20的混合溶液时,LDH/聚酰胺纳滤膜的镁锂分离因子为17,渗透性为1.15×10^(-4)L/(m^(2)·h·Pa),且在实验时间(100 h)范围内性能稳定,展现出良好的镁锂分离应用前景。Achieving the separation of magnesium and lithium in Salt Lake brine has become a huge challenge in the process of lithium extraction from salt lakes.Developing nanofiltration membranes with high magnesium lithium separation performance has become a key issue that needs to be urgently solved.In this study,porous layered double hydroxide(LDH)nanosheets were obtained by chemical etching,which were then deposited on the surface of polyacrylonitrile membrane as an intermediate layer.Then,the positively charged polyamide nanofiltration membranes were prepared on the surface of LDH by interfacial polymerization of polyethylenimine and trimesoyl chloride.The intermediate layer of LDH not only enhances the positive charge of the membrane surface,but also induces the formation of a coffee ring structure in the polyamide layer,improving the roughness of the membrane surface,thereby synchronously improving the selectivity and permeability of the membrane.When separating a mixture with a magnesium lithium ratio of 20,the LDH/polyamide nanofiltration membrane has a magnesium lithium separation factor of 17 with the permeance of 1.15×10^(-4)L/(m^(2)·h·Pa).Moreover,the separation performance of the membrane was stable within 100 h,demonstrating good prospects for magnesium lithium separation applications.

关 键 词：镁锂分离 纳滤膜 荷正电 层状双金属氢氧化物 中间层 高渗透性 

分 类 号：TQ028.8[化学工程]