Selective lithium recovery from aqueous solution using a modified membrane capacitive deionization system

- Electro-enhanced lithium ion recovery system is produced using lithium manganese oxide/activated carbon electrodes.
- Its lithium ion selectivity is investigated using an artificial synthetic brine solution.
- Lithium ion selectivity of the system is much higher than those for the other coexisting ions.
- The system exhibits good reproducibility in 5 consecutive recovery cycles.
- No morphological changes are observed in the adsorbent electrode.

Selective lithium recovery from aqueous solutions containing various cations (Li+, Na+, K+, Ca2 +, and Mg2 +) was tested using a modified membrane capacitive deionization system consisting of a lithium manganese oxide electrode for lithium ion capturing and a carbon electrode for anion capturing. The effect of cations and their concentrations on lithium ion selectivity was investigated. The results showed that the selectivity order found in the collected solutions was Li+ ≫ Mg2 + > Ca2 + > K+ > Na+. This order indicates that the ionic radius and oxidation state affect the selectivity. Approximately 0.35 μmol/g-adsorbent of lithium was recovered, which is 7 times higher than that from the physisorption process under the same experimental conditions. The required energy in the recovery process was calculated as 23.3 Wh/g of lithium. The results were reproducible, and no manganese dissolution was observed during 5 consecutive recovery cycles.