Boron extraction from lithium-rich brine using mixed alcohols

Abstract Boron removal from lithium-rich brine was systematically investigated by solvent extraction using 2,2,4-trimethyl-1,3-pentanediol (TMPD) dissolved in 2-ethylhexanol and sulfonated kerosene. The extraction parameters were determined, including the concentration of mixed alcohols, lithium and solvents loss. During the extraction, a single TMPD molecule reacted with a single boric acid molecule to form a complex with two C–O–B ester bonds. The mechanism was also verified using density functional theory (DFT). The overall extraction efficiency reached 99.95% by a two-stage countercurrent extraction. NaOH (0.2 mol/L) with an O/A phase ratio of 1:2 was used to strip the loaded organic phase with 99.99% stripping efficiency. The feasible industrial application of this boron extraction method was validated.