Extraction of 4F and 5F Elements with Substituted Malonamides

摘要

Diamides of carboxylic acids can be used as extractants for actinides (including trivalent ions) from radioactive wastes solutions in nitric acid medium. They could be an alternative to the mixture (carbomoylphosphonate-TBP) used in the TRUEX process. These solvents are interesting economicaly because they are easy to prepare and to purify. They are completely incinerable and don't create new wastes. Good results have been obtained with tetraalkylmalonamides. This paper deals with pentaalkyles propane diamides with generic formula: (RR'NCO)/sub 2/CHR'' where R and R' are dissymetric (for instance R = CH/sub 3/ and R' = C/sub 4/H/sub 9/). Extraction coefficients of Am/sup 3+/ are given to show the influence of R''. Increasing the length of R'' enhances the distribution coefficients. Good results are obtained with long oxyalkyl radicals, but there is an optimum in the size of the oxyalkyl radical, ramification has a weak influence. The substituent has an influence upon the surrounding of the metal extracted. In the case of simple malonamide four molecules of ligand participate in the complex formation and in the case of substituted amide only two. The better extraction by pentaalkylpropane diamide can be interpreted on the basis of higher molecular flexibility as shown by NMR data. Extraction of uranium, plutonium and fission products have also been done showing the pratical possibilities of these solvents. (ERA citation 13:002952)