Numerical Simulation of Continuous Extraction of Li(+) from High Mg(2+)/Li(+) Ratio Brines Based on Free Flow Ion Concentration Polarization Microfluidic System

Ion concentration polarization (ICP) is a promising mechanism for concentrating and/or separating charged molecules. This work simulates the extraction of Li(+) ions in a diluted high Mg(2+)/Li(+) ratio salt lake brines based on free flow ICP focusing (FF-ICPF). The model solution of diluted brine continuously flows through the system with Li(+) slightly concentrated and Mg(2+) significantly removed by ICP driven by external pressure and perpendicular electric field. In a typical case, our results showed that this system could focus Li(+) concentration by ~1.28 times while decreasing the Mg(2+)/Li(+) ratio by about 85% (from 40 to 5.85). Although Li(+) and Mg(2+) ions are not separated as an end product, which is preferably required by the lithium industry, this method is capable of decreasing the Mg(2+)/Li(+) ratio significantly and has great potential as a preprocessing technology for lithium extraction from salt lake brines.