Feasibility was established for direct dissolution-extraction of uranium employing adduct of N,N-dihexyl octanamide (DHOA), thus eliminating discrete aqueous phase and free acid usage. Various aspects of dissolution of solid uranium dioxide and extraction of uranium into molecular diluent viz. n-hexane and neoteric solvents viz. room temperature ionic liquid (RTIL) and supercritical carbon dioxide (SC CO 2 ) were studied. The organic adduct was found to have composition DHOA.(HNO 3 ) 0.78 (H 2 O) 0.4 . Adduct miscibility and UO 2 dissolution behavior was markedly different for RTIL and n-hexane. The dissolution process, studied by monitoring UV–Vis spectra, was found to be pseudo first order with a rate constant of of 0.074 min −1 and 0.036 min −1 for n-hexane and RTIL respectively. Irrespective of medium, dissolution-extraction efficiency of ≥90% was achievable. Using RTIL for dissolution-extraction medium and SC CO 2 for stripping is promising in terms of overall efficiency as well as RTIL recovery by avoiding aqueous cross contamination.

中文翻译：

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DHOA加合物在室温离子液体/超临界二氧化碳/正己烷中萃取无水UO2水溶液的对比研究

建立了使用N，N-二己基辛酰胺（DHOA）加合物直接溶解-萃取铀的可行性，从而消除了不连续的水相和游离酸的使用。溶解固体二氧化铀和将铀萃取到分子稀释剂中的各个方面。正己烷和现代溶剂，即。研究了室温离子液体（RTIL）和超临界二氧化碳（SC CO 2）。发现有机加合物的组成为DHOA。（HNO 3）0.78（H 2 O）0.4。对于RTIL和正己烷，加合物的混溶性和UO 2溶解行为明显不同。通过监测UV-Vis光谱研究的溶解过程被发现是伪一级反应，正己烷和RTIL的速率常数分别为0.074 min -1和0.036 min -1。不论媒介，溶出-萃取效率可达到≥90％。就整体效率以及避免水交叉污染而实现的RTIL回收而言，将RTIL用于溶出-萃取介质和SC CO 2用于汽提是有希望的。