Investigation of Mg²⁺/Li⁺ separation by nanofiltration

The Mg²⁺/Li⁺/Cl^- solutions were filtrated with a commercially available DK nanofiltration membrane to investigate the possibility to enrich the lithium component. The investigation was significant as such an approach might be a competing substitute for the present lithium purification industry and the environmental protection purpose. The Donnan steric pore model (DSPM) was implemented for the prediction. The separation of Mg²⁺/Li⁺ was mainly affected by the working pressure (or the permeation flux) and a limiting separation factor was found around 0.31. The effective membrane charge density was evaluated and its dependence on the permeation flux as well as the ion pattern was discussed. For predicting an actual separation of electrolytes, the experimental investigation seems necessary for the reliability and efficiency.