Hydroxylamine derivative in Purex process - Part VIII. The kinetics and mechanism of the redox reaction of N-methylhydroxylamine and vanadium(V)

The kinetic properties of the oxidation-reduction reaction between N-methylhydroxylamine (NMHAN) and vanadium(V) in nitric acid medium has been studied by spectrophotometry at 23.1degreesC. The rate equation of the redox reaction was determined as -d[V(V)]/dt=k[V(V)] [NMHAN] by investigating the influence of concentration of NMHAN, acidity, ionic strength and the ratio of initial concentration of V(V) to NMHAN on the reaction. The rate constant of the reaction k=0.818+/-0.051 (mol/l)(-1).s(-1) at the ionic strength of 1.00 mol/l. The activation energy of the redox reaction was calculated to be 39.6 kJ/mol. A possibly radical mechanism of the redox reaction between NMHAN and V(V) has been suggested on the basis of electron spin resonance (ESR) spectra of nitroxyl radical, i.e., CH3NHO. It is helpful to understand and make the redox mechanism of NMHAN and Np(VI) clear in the reprocessing process of nuclear spent fuel.