Reduction of neptunium(V) by hydrogen peroxide in the presence of oxalic acid

Journal Article · Thu Jan 01 04:00:00 EST 1987 · Sov. Radiochem. (Engl. Transl.); (United States)

OSTI ID:6715366

Malkova, N N; Matyukha, V A; Afanas'eva, T V; Krot, N N

Neptunium(V) in 0.5-4 M HNO/sub 3/ with H/sub 2/C/sub 2/O/sub 4/ concentration above O.05 M is irreversibly reduced by H/sub 2/O/sub 2/ according to a reaction, the order of which with respect to the reducing agent is equal to one, and with respect to the metal it varies from one to two. From an analysis of the kinetic curves, obtained by the spectrophotometric method, it follows that the slowest step of the reduction process is the direct reaction of NpO/sub 2//sup +/ ions with H/sub 2/O/sub 2/ molecules, leading to the formation of HO/sub 2/ radicals. The latter are subsequently capable of simultaneously reducing neptunium (V) and oxidizing neptunium(IV). An equation is derived that describes the kinetic curves of the reduction of neptunium(V) well. It was used to calculate the values of the rate constant of the direct reaction of NpO/sub 2//sup +/ with H/sub 2/O/sub 2/ and the value of ..cap alpha.. - the ratio of the rate constants of the reactions of HO/sub 2/ with neptunium(IV) and (V). It was shown that within the range of HNO/sub 3/ concentrations studied, 0.5-4 M, and H/sub 2/C/sub 2/O/sub 4/ 0.025-0.25 M, k/sub 1/ changes little. The parameter ..cap alpha.. decreases sharply with increasing H/sub 2/C/sub 2/O/sub 4/ concentration and with decreasing HNO/sub 3/ concentration. The corresponding values of the apparent activation energy were determined according to the temperature dependence of k/sub 1/ and ..cap alpha... The similarity and difference of the processes of reduction of neptunium(V) by H/sub 2/O/sub 2/ in nitrate-oxalate media and concentrated HNO/sub 3/ solutions are discussed.

• OSTI ID: 6715366
• Journal Information: Sov. Radiochem. (Engl. Transl.); (United States), Journal Name: Sov. Radiochem. (Engl. Transl.); (United States) Vol. 28:3; ISSN SVRDA
• Country of Publication: United States
• Language: Russian

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
ACTINIDE COMPOUNDS
ACTINIDES
CARBOXYLIC ACID SALTS
CARBOXYLIC ACIDS
CHALCOGENIDES
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
COMPLEXOMETRY
DICARBOXYLIC ACIDS
ELEMENTS
EQUATIONS
HYDROGEN COMPOUNDS
HYDROGEN PEROXIDE
INORGANIC ACIDS
KINETIC EQUATIONS
KINETICS
METALS
NEPTUNIUM
NEPTUNIUM COMPOUNDS
NEPTUNIUM NITRATES
NEPTUNIUM OXIDES
NITRATES
NITRIC ACID
NITROGEN COMPOUNDS
ORGANIC ACIDS
ORGANIC COMPOUNDS
OXALATES
OXALIC ACID
OXIDES
OXYGEN COMPOUNDS
PEROXIDES
QUANTITY RATIO
REACTION KINETICS
REDOX POTENTIAL
REDUCING AGENTS
REDUCTION
SPECTROPHOTOMETRY
TRANSURANIUM COMPOUNDS
TRANSURANIUM ELEMENTS
VALENCE