THE FORMATION OF A THIRD PHASE IN THE SIMULTANEOUS EXTRACTION OF ACTINIDE(IV) AND URANYL NITRATES BY TRIBUTYL PHOSPHATE IN DODECANE

Short Alternative Route for Nuclear Fuel Reprocessing Based on Organic Phase Self-Splitting

A more sustainable management of natural resources and the establishment of processes allowing a joint management of nuclear materials to avoid their diversion from their civilian use are two issues for the nuclear industry. Short alternatives to existing processes have therefore been proposed based on known systems available, tributylphosphate (TBP), for the separation of actinides by liquid/liquid extraction. Proof of concept of such alternative has been established on the uranium(VI)/thorium(IV) system. From an organic phase consisting of a mixture of TBP/n-dodecane loaded with uranium and thorium, two fluxes have been obtained: the first contains almost all of the thorium in the presence of uranium in a controlled ratio, the second contains surplus uranium. Two levers were selected to control the spontaneous separation of the organic phase: the addition of concentrated nitric acid, or the temperature variation. Best results have been obtained using a temperature drop in the liquid/liquid extraction process, and variations in process conditions have been studied. Final metal recovery and solvent recycling have also been demonstrated, opening the door for further process development.

Transcriptomic analysis of the highly efficient oil-degrading bacterium Acinetobacter venetianus RAG-1 reveals genes important in dodecane uptake and utilization

The hydrocarbonoclastic bacterium Acinetobacter venetianus RAG-1 has attracted substantial attention due to its powerful oil-degrading capabilities and its potential to play an important ecological role in the cleanup of alkanes. In this study, we compare the transcriptome of the strain RAG-1 grown in dodecane, the corresponding alkanol (dodecanol), and sodium acetate for the characterization of genes involved in dodecane uptake and utilization. Comparison of the transcriptional responses of RAG-1 grown on dodecane led to the identification of 1074 genes that were differentially expressed relative to sodium acetate. Of these, 622 genes were upregulated when grown in dodecane. The highly upregulated genes were involved in alkane catabolism, along with stress response. Our data suggest AlkMb to be primarily involved in dodecane oxidation. Transcriptional response of RAG-1 grown on dodecane relative to dodecanol also led to the identification of permease, outer membrane protein and thin fimbriae coding genes potentially involved in dodecane uptake. This study provides the first model for key genes involved in alkane uptake and metabolism in A. venetianus RAG-1.

Analysis of the transcriptome of the oil-degrading bacterium Acinetobacter venetianus RAG-1 helps in identification of genes that are involved in uptake and metabolism of alkanes, thus helping in bioremediation.

Distribution coefficients of UO2(NO3)2· 2TBP in supercritical fluid CO2as determined by on-line time resolved laser induced fluorescence

Time resolved laser induced fluorescence has been used for on-line analysis of uranium extraction from acidic solutions with tributyl phosphate modified supercritical carbon dioxide. Thein-situmeasurement allows direct characterization of the supercritical fluid extraction. The extractions were found to be first order with respect to uranium and the distribution coefficient was observed to increase with temperature and tributyl phosphate concentration.