Highly efficient extraction of lithium from salt lake brine by LiAl-layered double hydroxides as lithium-ion-selective capturing material

The extraction of lithium from salt lake brine in the Chinese Qaidam Basin is challenging due to its high Mg/Li and Na/Li ratios. Herein, we utilized a reaction-coupled separation technology to separate sodium and lithium ions from a high Na/Li ratio brine(Na/Li = 48.7, w/w) and extracted lithium with Li Al-layered double hydroxides(Li Al-LDHs). The Li Al-LDHs act as lithium-ion-selective capturing materials from multication brines. That is, the lithium ions selectively enter the solid phase to form Li Al-LDHs, and the sodium ions are still retained in the liquid phase. This is because the lithium ions can be incorporated into the structural vacancies of LiAl-LDHs, whereas the sodium ions cannot. The effects of reaction conditions on lithium loss and separation efficiency were investigated at both the nucleation and the crystallization stage, e.g., the nucleation rotating speed, the Li/Al molar ratio, the crystallization temperature and time, and co-existing cations. The lithium loss is as low as 3.93% under optimal separation conditions.The sodium ions remained in the solution. Consequently, an excellent Na/Li separation efficiency was achieved by this reaction-coupled separation technology. These findings confirm that LiAl-LDHs play a critical function in selectively capturing lithium ions from brines with a high Na/Li ratio, which is useful for the extraction of lithium ions from the abundant salt lake brine resources in China.

丁酮-水分离新方法研究

针对工业上采用蒸馏法分离丁酮┐水体系能耗大的问题，研究了加有盐类的复合萃取剂对该体系的萃取分离效果。结果表明：ＣＬ，ＣＭ盐能明显地改变丁酮┐水之间的互溶度，大幅度地增大萃取剂对组分的萃取分配系数和选择性系数，达到分离提纯丁酮的目的。进一步研究了萃取工艺参数对分离效果的影响。经初步热量衡算表明，应用本研究方法分离丁酮┐水可比传统的蒸馏法节省７０％的能耗。

环己酮-水分离新方法的研究

针对工业上传统的蒸馏法分离环己酮－水体系能耗过大的问题，研究了含盐类的复合萃取剂对该体系的萃取分离效果。结果表明，ＬｉＣｌ、ＭｇＣｌ２能明显改变环己酮与水之间的互溶度，大幅度提高复合萃取剂对组分的萃取分配系数和选择性系数，达到分离提纯环己酮的目的。进一步研究了萃取工艺参数对分离效果的影响。经初步热量衡算表明：应用本法分离环己酮－水比传统的蒸馏法节省能耗约２５％。