Effect of hydrophobicity of extractant on extraction equilibrium of lithium with a mixture of beta-diketone and neutral phosphorus compounds

Using three kinds of novel beta-diketone of different alkyl-chain length (1 -phenyl-1,3-octanedione, 1 -phenyl-1, 3-tetradecanedione and 1-phenyl-1,3-i cosanedione) and four Binds of neutral phosphorus compounds of different al kyl-chain length (tri-n-butylphosphine oxide, tri-n-octylphosphine oxide, t ri-n-butylphospate and tris(2-ethylhexyl) phosphate, the extraction equilib rium of lithium was investigated, and the synergistic effect of these extra ction systems was examined, in order to determine the optimum extraction sy stem for lithium. t is found that lithium is synergistically extracted by the mixture of beta -diketone and neutral phosphorus compounds, and that the ability of lithium extraction with the synergistic reagent of trialkylphosphine oxide is high er than that with tri-alkylphosphate. However, the effect of alkyl-chain le ngth of beta-diketone on the extraction equilibrium constants is negligibly small. These results are confirmed by molecular modeling of the extractant s and synergistic reagents.