【摘要】 用反相纸层析技术研究了β-二酮(PMBP、HTTA与HBA)与有机磷酸(P538、P204、P507)组成的体系对稀土的协萃效应。提出两种萃取剂都是以酸性配体形式起作用,协萃效应与两种萃取剂的pKa大小及萃取剂的空间位阻有关。当两种萃取剂的pKa相差较大时,β-二酮的酸式电离被抑制,大大减弱了配位能力,协萃效应很弱。当两种萃取剂的pKa相近,同时空间位阻较小时,协萃效应最为显著。更多还原

【Abstract】 The synergistic effect of Ln with such a system consisted of a β-diketone (PMBP, HTTA, HBA) and an organophosphoric acid (P538, P204 and P507) was studied by means of reversed-phase paper chromatographic technique. There is a relationship existing between the synergistic effect and the difference of pKa of the two extractants containing in this system. The synergistic effect is also affected by the steric hindrance. Because the acidity of β-diketone is weaker than that of organophosphoric acid, and the major coordination form of β-diketone is the acidic enol form, so that if the difference of pKa is large enough, the synergistic effect will be very weak or even can’t be observed due to the acidic dissociation of β-diketone depressed by the organophosphoric acid. On the other hand, the better synergistic effect will be given by such systems, in which the steric hindrance of these two ligands are small and their pKa are near to each other. It suggested that two extractants will both act as an acidic ligand and was supported by the results given from IR spectrum.更多还原