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近年来,在研究溶剂萃取时,发现两种或两种以上萃取剂的混合物萃取某一金属化合物时,其分配系数要比单独使用一种萃取剂时高很多,这就是所谓协同效应。1958年首先由勃雷克(C.A.Blake)等人提出这个名词,他们在使用二-(2-乙基己基)磷酸(D2EHPA)和磷酸三丁酯(TBP)煤油混合溶剂从硫酸体系中萃取UO_2~(++)时,发现其萃取能力很大,并对此混合物的组成和产生协同的机理作了解释。但实际上早在1954年克宁哈姆(J.G.Cunningham)等人在用硫国酰基三氟丙酮(TTA)和TBP与苯的混合溶剂萃取镨和钕的硝酸化合物时就已发现了这种现象。肯尼迪(J.Kennedy)认为D2EHPA和TBP混合物对PuO_2~(++)同样有协同效应的存在,并在以后很多工作中提出了对协同机构的解释。最近欧文(H.Inving)发表的一系列工作,有力地证明了TTA和中性磷酸酯TBP及TBPO(三丁基氧化膦)的环己烷溶液对锕系元素UO_2~(++),Pu~(3+),Pu~(4+),Am~(3+),Th~(4+),Np~(4+)和镧系元素Eu~(3+),以及第一过渡系的金属离子,均有协同效应的存在,并确定了各种被萃取化合物的组成和求算了它们的平衡常数,对协同效应产生的机理亦提出了较为全面的看法。海莱(T.V.Healy)较广泛地研究了从盐酸体系中用不同中性磷试剂和TTA的混
In recent years, when studying solvent extraction, when a mixture of two or more extractants was found to extract a certain metal compound, its partition coefficient was much higher than that when a single extractant was used alone. This is called synergistic effect. The term was first proposed by CABlake et al. In 1958 and was used to extract UO 2 from sulfuric acid systems using a mixture of di (2-ethylhexyl) phosphoric acid (D2EHPA) and tributyl phosphate (TBP) kerosene ~ (++), it is found that its extraction ability is great, and the composition of the mixture and the mechanism of synergism are explained. But in fact, as early as 1954, JG Cunningham et al. Discovered this phenomenon when extracting nitric acid compounds of praseodymium and neodymium with thionyl trifluoroacetone (TTA) and a mixed solvent of TBP and benzene . J. Kennedy argues that the D2EHPA and TBP blends also have a synergistic effect on PuO_2 ~ (++), and the interpretation of the collaborative agency has been proposed in many of the future work. A series of recent work published by H. Inving strongly proved that the effects of TTA, neutral phosphate TBP and cyclohexane solution of TBPO (tributylphosphine oxide) on actinides UO 2 ~ (++), Pu (3 +), Pu ~ (4 +), Am ~ (3 +), Th ~ (4 +), Np ~ (4+) and lanthanide Eu ~ (3+) Metal ions, have synergistic effects exist, and to determine the composition of a variety of compounds extracted and calculated their equilibrium constant, the mechanism of the synergistic effect also put forward a more comprehensive view. T.V. Healy has more extensively studied the use of different neutral phosphorous reagents and TTAs in a hydrochloric acid system