Application of bipolar membrane electrodialysis (BMED) for simultaneous separation and recovery of boron and lithium from aqueous solutions

Simultaneous separation and recovery of lithium and boron from the aqueous solution prepared by dissolving lithium tetraborate using bipolar membrane electrodialysis (BMED) was studied to investigate the effect of applied potential and initial concentrations of lithium and boron as well as co-existing ions in the solution. The results revealed that mass transfer rates of lithium and boron increased with applied voltage up to a maximum limit voltage. Good linear correlation between initial concentrations and transfer rates of lithium and boron was helpful to elucidate the mass transfer mechanism which can be explained by Fick's first law of diffusion. The permeation of lithium and boron through the membrane were little bit affected by the applied voltage and also by the initial concentrations of lithium and boron. The influence of co-existing sodium or chloride ions on the BMED performance was not observed. The separation efficiencies of lithium and boron were quite high with a BMED performance > 90%. The current efficiency of lithium and boron gradually decreased with an increase in the applied voltage while specific power consumption increased with an increase in the applied voltage.