The Role of Hydroxamic Acids in the Retention of Fission Products in TBP Diluents. A Quantitative Study in a Model System

Abstract

The degradation with nitric acid of kerosene-type diluents of TBP in the reprocessing of nuclear fuel leads to the formation of primary nitroalkanes. These, under acid conditions, may hydrolyze to hydroxamic acids, HA, which are well-known complex-ing agents of many metal ions, including ⁹⁵Zr. The formation of very stable HA-⁹⁵Zr complexes has been proposed as a rationale for the retention of ⁹⁵Zr in the diluents. However, the results of this study carried out in a model system, the acid-catalyzed conversion of 1-nitropropane to propanhydroxamic acid, and the subsequent hydrolysis to carboxylic acid and hydroxylamine—easily extensible to the actual reprocessing processes—indicate that in these systems the equilibrium concentration of hydroxamic acids attainable is too low (10^?8 to 10^?9 M) to account for the “zirconium retention” phenomenon.