【摘要】 本文用分配比测定平衡常数法、等摩尔系列法测萃合物组成,用凝固点降低法测有机相TOA的表观分子量,并以萃合物的红外光谱加以佐证。实验表明在C⁰_H2SO=1.97M时,TOA萃取U（VI）生成的萃台物为（R₃NH）₄UO₂（SO₄）₃,logβ₁0=4.83;在pH=2.3、[SO₄^2-]=0.5M时,则生成（R₃NH）₂UO₂（SO₄）₂萃合物,萃取平衡常数logβ＇₁0=10.0。胺铀比从4:1转变为2:1,这就解释了为什么pH>2时D_U又回升的现象。更多还原

【Abstract】 The extraction of uranium (VI) by organic amine compound is quite a complex physico-chemical process. Depending on the acidity of the aqueousphase, the amine salt may exist in different species-the bisulfate salt(R3NH)HSO4, the sulfate salt (R3Nll)2SO4 an their mixture In high acidity or a mixtrue of the amine sulfate salt an ’ the free amine at low acidities. Different viewpoints have been emerged from the extraction mechanism of uranium (VI) by tertiary amine in the sulfate solution as occurring by either one of the mechanisms, that is the anion exchange mechanism and the adduct formation reaction.W. J. McDowell suggeste : that both extraction mechanism can occur simultaneously and which one is favored that is dependent on the concentration of the sulfate ion in the aqueous phase. At higher sulfate ion concentrations the uranium is present to a large extent as the complex disulfate anlon and the anion exchange mechanism pre ominates, whereas at lower sulfate ion concentration, quite high amounts of the neutral or cationic uranium species exist an the a uct formation mechanism predominates, when fixed to the concentration of sulfate 0.5M, the anion exchange mechanism predominates owing to the ifferent pH of the aqueous phase, herein raises an issue whether the extracte complex is (R3NH)2UO2(SO4)2 or (R3NH)4UO2(SO4)2. According to C. F. Colman it is the formeer whereas C. Boirie pointe out it is the latter, while oing research on the properties of the extaction of uranyl sulfate by the tertiary amine N-235, Yuan Cheng-ye change pH of the aqueous phase from 0.8 to 2.2. The partition coefficient of uranium increase with the rising pH until the maximum value appeare an then it ecreased at pH 1.4 to 1.6. But at pH 2, it is har to explain why the partition coefficient of uranium raised again. The same situation was reporte by theORNL engage in the extraction of uranium (VI) from the leached solution of uranium ores by trioctylamine. This paper suggests that the characteristics of the partition coefficient of uranium originate from the change in pH of aqueous phase thereby leading to the change in the composition of the extractable species. Experimental results showe that the extractable species of uranium formated at 1.97M H2SO4 are (R3NH)4UO2(SO4)3 an (R3NH)2UO2(SO4), at pH 2.3 and the logarithm of the equilibrium constants β10 was foun to be 4.83 and 10.0 respectively. The mole ratio of ToA to uranium (VI) Was transformed from 4:1 to 2:1. This phenomenon explained why the Partition coefficient of uranium (VI) was increased at pH 2. The composition of the extractable species was confirmed by the methods of slope analysis, equimolar series. An infrared spectra of the extractable species reinforced the evidence. The synergistic extraction mechanism of uranyl sulfate by tri-n-octyla mine and di-2-ethylhexylphosphoric acid in benzene solution in 1.97MH2SO4 has been investigated. The binary synergistic extracted equilibrium constant was determined to be logβ12=8.71 and the composition of synergistic extracted complex (R3NH)4UO2(SO4)2(HA2)2 was proved by slope method.更多还原