Extraction equilibria of lithium with N,N-bis(2-ethylhexyl)-3-oxobutanamide and tributyl phosphate in kerosene and FeCl3

The application of the β-carbonyl amide N,N-bis(2-ethylhexyl)-3-oxobutanamide for the extraction of lithium ions from saturated MgCl2 solutions was investigated using tributyl phosphate (TBP) as the second component in a mixed extractant and FeCl3 as the co-extractant. The effects of the extractant concentrations, H+ solution concentrations, phase ratios, Fe/Li molar ratios, and other factors on the extraction were fully investigated. Our results demonstrate that compared to conventional extraction systems, a higher Li-to-Mg separation factor of 450-700 can be obtained, and the formation of phase interface objects can be effectively avoided under low solution acidity without emulsification. The mechanism suggests that (LiFeCl4·2TBP·NB2EHOTA)·4TBP·NB2EHOTA is formed at lower (10%) TBP/NB2EHOTA mixed concentrations. This paper reports the application of β-carbonyl amide extractants for Li separation from salt lake brine with high Mg-to-Li ratios.