Microfluidic Separation Technology For Impurities In Uranium

Despite its simplicity and versatility for the determination of trace levels of contaminants in a sample, Liquid-Liquid extraction does not always meet the requirements of modern analytical chemistry. For instance, it is a time-consuming, tedious, multistage operation and it requires high consumption of often hazardous organic solvents, which suggests the high production of organic waste. Microfluidic platforms provide several advantages for liquid-liquid extraction processes over conventional methods, for example with respect to lower consumption of solvents and enhanced extraction efficiencies due to the inherent shorter diffusional distances.In this study, the optimization of the liquid-liquid extraction of uranium(VI) in HNO3 media by Tributylphosphate(TBP) and Trialkyphosphine oxide(TRPO) were performed in microsystem through the investigation of the influence of different parameters. For instance, the flow rates, the length as well as the specific interfacial area were varied and the optimized conditions lead to an extraction yield of 99% in a two-phase microsystem for an aqueous contact time of only 38 s in a microchannel. Here, the expected advantages of the miniaturization are clearly highlighted with a considerable reduction of the analysis time and while keeping similar extraction performances as those obtained in batch at the equilibrium. The investigation of the influence of different parameters (flow rates, length of the microchannel, specific interfacial area), it was shown that the same performances of liquid-liquid extraction can be obtained in microsystem and in batch.An analytical procedure was developed to determine the concentration of 21 impurities (Li?Na? Mg? Al?Ca, Ti?V?Cr?Mn?Co?Ni?Cu?Zn? As? Se? Sr? Mo, Ag? Cd? Pb and Bi) in a uranium matrix using the inductively coupled plasma mass spectrometry (ICP-MS). For all of the 21 elements of interest,Mg?Al?Ca?V?Cr?Ni?Cu?Sr?Agand Pb are in perfect agreement with the certified value and with an accuracy better than 10%. Li? Na?Mn?Co?Zn?As?Se?Cd and Bi are in perfect agreement with the certified value and with an accuracy better than 20%.Nevertheless, the experiments whose results are reported in the present work, although not at all optimized, demonstrate the advantages of the miniaturized analytical techniques and constitute a proof of concept and a first step towards a global analytical process with continuous flow.