HPMBP-P507-TBP三元协萃Gd^(3+)

SYNERGISTIC EXTRACTION OF Gd^(8+) BY TERNARY SYSTEM OF AAB SPECIES COMPOSED OF HBMBP-P507-TBP IN TOLUENE

本文研究1-苯基3-甲基4-苯甲酰吡唑啉酮-5HPMBP)、2-乙基己基膦酸2-乙基己基酯(P507)与磷酸三丁酯(TBP)的甲苯溶液,从高氯酸底液中萃取钆机理。实验发现Gd^(3+)有三元协萃效应。该体系属于螯合中性络合AAB类协萃体系。其一元、二元和三元萃取平衡常数分别为lgβ_1=-4.24(HPMBP),lgβ_1=-2.88(生成Gd(PMBP)_3(HBMBP));lgβ_(12)=-1.04(HPMBP-P507);lgβ_(13)=-0.316(HPMBP-TBP);lgβ_(13)=1.87(生成Gd(PMBP)_3·2TBP);lgβ_(123)=1.04(HPMBP-P507-TBP)。

Trivalcnt lanthanide systems have been shown to exhibit variable coordination number ranging from 6 to 12 with which 7 and 8 are a common sight .Those ions which have the coordination number twice as large as the number of valence electrons may easily produce synergic effect.In order to prove the regularity of synergistic extraction and the exploration of new ternary synergic system proposed by Xu Guangxian and to search a new solvent extract systm for separating the lanthanide elements, the synergic extraction of Cd3+ from perchloric acid solution by HBMBP P507-TBP in toluene was studied. The system is composed of two chelate extracting ligands and one neutral extractants, namely AAB species.The equilibrium constants were determined to be logB1=-4.24 (HPMBP system, extracted complex Gd(PMBP)3) , logB1 =-2.88(extracted complex Gd(PMBP)3(HPMBP)) , logB12=-1.04 (HPMBP-P507 system, synergic complex Gd(HA2)(PMBP)2) , logB13 = -0.316(HPMBP-TBP system, synergic complex Gd(HMBP)3TBP) , logB13 = 1.87(synergic complex Gd(PMBP)32TBP), logB123 = 1.04(HPMBP-p507-TBP system,ternary synergic complex Gd(HA2)(PMBP)2TBP) respectively. According to Xu Guangxian's opinion, the synergistic effect of chelate, neutral complex in ternary system arises from satisfying the electricity neutrality principle, loss-of-hydrophilic principle and coordinate substitution principle.From the structure of ternary extraction compound, it is shown that the existence of the different size molecules of P507 and PMBP increases the unsymmetry of coordinate ions. Perhaps that is the reason to produce an obvious ternary synergic effect.