Oxidation–reduction reactions of simple hydroxamic acids and plutonium(IV) ions in nitric acid

Abstract

SummarySimple hydroxamic acids such as formo- and aceto-hydroxamic acids have been proposed as suitable reagents for the separation of either Pu and/or Np from U in modified or single cycle Purex based solvent extraction processes designed to meet the emerging requirements of advanced fuel cycles. The stability of these hydroxamic acids is dominated by their decomposition through acid hydrolysis. Kinetic studies of the acid hydrolysis of formo- and aceto-hydroxamic acids are reported in the absence and the presence of Pu(IV) ions. The slow reduction of these plutonium(IV) hydroxamate complexes to Pu(III) aquo-ions has been characterised by spectrophotometry and cyclic voltammetry. The reductions of Pu(IV) in the presence of FHA and AHA are consistent with a mechanism in which free hydroxamic acid in solution is hydrolysed whilst Pu(IV) ions remain fully complexed to hydroxamate ligands; then at some point close to a 1 : 1 Pu(IV) : XHA ratio, some free Pu

Acetohydroxamatoiron(III) Complexes: Thermodynamics of Formation and Temperature Dependent Speciation

“…Whilst there have been many studies of hydroxamic acid hydrolysis and their complexation reactions with Fe(III) ions, there have been relatively few studies of the stability of the Fe(III)-hydroxamate complexes towards hydrolysis. We have previously reported on the kinetics of the hydrolysis of hydroxamic acids both in free solution and when bound to metal ions and developed a kinetic model describing this process at ambient temperatures [11,13]. However, the applications of hydroxamic acids in biological-related fields requires an understanding of the behaviour of these systems at temperature of biological interest, for example in vivo (310K) or temperatures at which proteins start to denature ( ~ 325K) [14].…”

Literature Review: Reduction of Np(v) to Np (Iv)-Alternatives to Ferrous Sulfamate

“…10 The catalyst was prepared by impregnating the 3-5nm Al 2 O 3 particles with a Pt solution. The product was dried at 70 °C and subsequently calcined for 3 hr at 600 °C.…”

The effect of acetohydroxamic acid on stainless steel corrosion in nitric acid

“…As part of an Advanced PUREX process (Adv-PUREX), the use of acetohydroxamic acid (AHA) has been proposed as a means to hold back Pu and Np in the aqueous phase, thus allowing U(VI) to be extracted into the TBP without Pu/Np contamination [2][3][4][5][6]. This has led to the development of a variety of advanced fuel cycle concepts that incorporate AHA, such as URanium EXtraction Plus (UREX+) [7,8] and Grouped ActiNide Extraction (GANEX) [9,10], which do not extract pure plutonium but rather a mix of Pu, Am and Np, providing a non-proliferation advantage over the traditional PUREX process [11].…”