Posted by Lithium resources are widely used in battery industry, ceramic and glass industry, lubricating grease production, continuous casting process and many other fields due to their good electrochemical properties, extremely high redox potential and specific heat capacity. The market demand is huge, and its extraction issues have also received widespread attention. More than 60% of lithium resources are contained in salt lake brine and seawater in the form of ions. The extraction process is often interfered by Mg2+, which has similar properties to Li+, resulting in low separation efficiency or high separation cost.
Therefore, the unavoidable problem in the research of liquid-phase lithium resource extraction is Li+/Mg2+ separation.
Researchers at Ocean University of China (which is a key comprehensive university with unique strengths in oceanography and fisheries) filed a patent application under number CN115738757 desribing a method for preparing a monovalent cation selective separation membrane based on a sulfobutyl-β-cyclodextrin ion transport channel. The cation selective separation membrane has high Li+-selectivity.
Blue Star Hangzhou Membrane Industries Co Ltd and Hangzhou Water Treat Technology Development Center Co Ltd jointly filed a patent application (CN115738742) for a preparation method of a positively charged membrane for extracting lithium from a salt lake comprising polyethylene imine / cyclodextrin polyrotaxane with high magnesium-lithium salt separation rate even at high water flux. The unique characteristics of the membrane enable operation at temperature of the water bath between 70-95°C, with treatment time about 2-6 minutes.