从高放废液中分离锕系元素的TRPO流程是我国自主研发、具有良好应用前景的分离流程。为了提高其综合性能，致力于完善TRPO流程，尤其是锕系元素反萃工艺的研究工作从未间断。本论文选取四甲基双酰胺荚醚（N,N,N’,N’-四甲基-3-氧杂-戊二酰胺，简写作TMDGA）作为水相配位反萃剂，研究了它与锕系元素和裂片/腐蚀产物的配位行为以及从负载TRPO中反萃锕系元素及其他金属离子的性能。TMDGA是一种只含CHON的化合物，水相中溶解性优良，在30%TRPO/煤油体系中的溶解度非常小。温度达到200 oC TMDGA开始分解，分解产物为气体，不产生二次固体废物。TMDGA中两个羰基氧和醚键氧均可参与配位。TMDGA与Ln(III)、An(III, IV)和Zr(IV)最多形成三级配合物。金属离子与TMDGA配位的化学计量稳定常数由液-液萃取法测定。Ln(III)、An(III, IV)和Zr(IV)均可与TMDGA形成稳定的配合物；低酸度水解可能会降低Np(IV)和Pu(IV)的配位稳定性。TMDGA与Pu(IV)或Np(IV)配位是吸热反应，与Am(III)配位是放热反应；配位反应均可自发进行（ΔGθ < 0）。金属离子在TMDGA/硝酸 - 30%TRPO/煤油体系中的分配比受TMDGA浓度和体系酸度的影响。随着TMDGA浓度增加，Ln(III)、Y(III)、Zr(IV)、Am(III)、Np(VI)和Pu(III,IV)的分配比明显下降；而Mo(VI)、Fe(III)、Ru(III)、Pd(II)、Tc(VII)和U(VI)的分配比没有明显变化。多数金属离子的分配比随酸度的增加先增大后减小，但是Zr(IV)和Np(VI)的分配比随酸度升高而增大。TMDGA对Np(IV, VI)的有效反萃需要低酸度（< 0.3 mol/L）条件。有机相负载的Mo(VI)会导致Np(IV)的反萃不完全，可能是因为部分Np(IV)与Mo(VI)和TRPO分子结合成难以被反萃的多核配合物。残余Np(IV)可由稀草酸和TMDGA的混合溶液完全反萃。基于上述实验结果，设计了从负载TRPO中反萃锕系元素的概念流程：先用0.2 mol/L TMDGA五级反萃Am(III)、Pu(IV)、镧系元素和大部分Np(IV)，再用0.1 mol/L 草酸和0.1 mol/L TMDGA的混合溶液四级反萃残留Np(IV)，最后用5%碳酸铵三级反萃铀。串级实验结果表明该概念流程紧凑、操作酸度低、可实现超铀元素的整体反萃，超铀元素和铀之间无交叉污染，具有较好应用前景。
TRPO process, for actinides partitioning from high level waste, was independently developed in China and has a good application prospect. In order to enhance its performance, TRPO process, especially its actinide stripping process, was continuously improved. N,N,N’,N’-tetramethyl diglycolamide (TMDGA) is applied as a water-soluble coordinating stripping-agent. Its coordination behaviors with actinides or fission/ corrosion products and the stripping performance for these metallic ions from TRPO were studied in the present dissertation. TMDGA is a kind of only CHON ligand. It dissolved well in the aqueous phase, but hardly in 30% TRPO/kerosene. TMDGA was decomposed from 200 oC. The decomposition products were gases without generation of secondary solid wastes . TMDGA coordinated with the metallic ions by two carbonyl oxygens and the ether oxygen. Up to three TMDGA molecules were involved in the formation of complexes with Ln(III), An(III, IV) and Zr(IV). The stoichiometric stability constants of TMDGA complexes were determined by liquid-liquid extraction method. TMDGA could coordinate with Ln(III), An(III, IV) and Zr(IV) with high stability constants. Hydrolysis of metallic ions might reduce the stability of Np(IV)-TMDGA and Pu(IV)-TMDGA complexes. The coordination reaction was endothermic for Pu(IV)-TMDGA and Np(IV)-TMDGA, exothermic for Am(III)-TMDGA; and these coordination reactions were spontaneous (ΔGθ < 0). The distribution ratios of metallic ions in TMDGA/HNO3 - 30% TRPO/kerosene system were influenced by the concentration of TMDGA and the aqueous acidity. With the increase in TMDGA concentration, distribution ratios of Ln(III), Y(III), Zr(IV), Am(III), Np(VI) and Pu(III,IV) decreased significantly; while, those of Mo(VI), Fe(III), Ru(III), Pd(II), Tc(VII) and U(VI) were almost kept unchanged. With the increase in acidity, distribution ratios of most metal ions increased first and then decreased; while, those of Zr(IV) and Np(VI) increased monotonically. Effective stripping of Np(IV, VI) should be conducted in low acidity (< 0.3 mol/L). The loaded Mo(VI) in organc phase might cause the reservation of Np(IV), probably because of the formation of polynuclear complexes of Np(IV), Mo(VI) and TRPO. The residual Np(IV) in organic phase could be removed by the mixture of TMDGA and dilute oxalic acid.Accordingly, a conceptual process was proposed to strip actinides from loaded TRPO organic phase: first, Am(III), Ln(III), Pu(IV) and most Np(IV) were stripped by 0.2 mol/L TMDGA through 5-stage stripping; then, the residual Np(IV) was removed by the mixture of 0.1 mol/L TMDGA and 0.1 mol/L oxalic acid through 4-stage stripping; finally, U(VI) was stripped by 5% ammonium carbonate solution through 3-stage stripping. The experimental results of cascade extraction show that the compact conceptual process can strip transuranic elements together in low acidity and effectively separate them from uranium. The proposed stripping process is promising.
