Magnetic Field-Assisted Bundled Capillary Chromatography for Uranium and Lithium Extraction from Salt Lakes

Bundled capillary chromatographic columns with methyl vinyl silicone rubber (MVQ) and polytetrafluoroethylene (PTFE) as substrates were fabricated and assisted by a ring magnetic field for the synchronous extraction of uranium and lithium from salt lakes. Through multiple groups of comparative experiments, the optimal peristaltic pump rotational speed was determined to be 1.81 mL/min and the optimal magnetic field-assisted method for separation is when a ring magnet is nested, with its magnetic field lines pointing opposite to the water flow direction (“S-N”). Among them, the MVQ capillary showed better performance. Without an external magnetic field, the uranium-lithium separation factor and magnesium-lithium separation factor of the MVQ capillary chromatographic column were 1.32 and 1.008, respectively; it required 289 stages of separation to reduce the magnesium-lithium ratio from 200 to 20. Under the action of the “S-N” magnetic field, the uranium-lithium separation factor of the MVQ capillary chromatographic column increased to 1.41, the magnesium-lithium separation factor increased to 1.015, and only 155 stages of separation were needed to reduce the magnesium-lithium ratio to 20. Moreover, the action mechanism of the magnetic field was explored, the possible impact of the liquid membrane on the separation process was further verified, and the movement mechanism of ions inside the capillary chromatographic column was analyzed in depth. The results demonstrate that the external magnetic field can be used to improve the separation and extraction efficiency of uranium and lithium from salt lakes, providing new insights for relevant research.