Novel approach for recovering lithium from simulated aqueous solutions using carbon dioxide microwave plasma

An approach for recovering lithium from aqueous solutions containing lithium was developed via lithium carbonate (Li2CO3) precipitation through a carbonate mineralization reaction. To enhance the lithium recovery rate, carbon dioxide (CO2) plasma was used to precipitate lithium as Li2CO3. The Li2CO3 precipitate, filtered from the aqueous solution, was analyzed by X-ray diffraction and then confirmed to be Li2CO3 by comparing with commercial Li2CO3. Comparative experiments between CO2 gas and CO2 plasma revealed a significant improvement in the lithium recovery efficiency by 3 times on using CO2 plasma. The amount of remaining lithium in the aqueous solution before and after the reaction was quantified and analyzed by inductively coupled plasma mass spectrometry. Plasma generation was achieved using a 2.45 GHz microwave plasma torch by utilizing CO2 as the discharge gas and allowing immediate reaction with the aqueous solution. Plasma characteristics were analyzed using an optical emission spectrometer to observe the emitted radicals and calculate the rotational temperature of the CO2 plasma. The future potential of this technology for the recovery of lithium from seawater was also investigated.