Oxidation of hydroxylamine by nitrous and nitric acids

New insights into the mechanism of nitrite reduction on a platinum electrode

“…Following the arguments of Gadde and Bruckenstein [1], the ring current may be thought of as a sum of currents ascribable to the oxidation of HNO 2 and NH 3 OH + . It must be noted, however, that this is an approximation which is true only if the two molecules do not react with each other, a condition which is apparently not completely fulfilled [34][35][36] for the present case. While the oxidation current will be mainly influenced by the presence of a highly electroactive species such as hydroxylamine, the decrease in reduction current is mainly explained in terms of the shielding of the ring due to nitrous acid consumption at the disk.…”

Model for predicting hydroxylamine nitrate stability in plutonium process solutions

“…The chemical reactions involved in the autocatalytic oxidation of hydroxylamine nitrate (NH 3 OHNO 3 ) with nitric acid have been proposed by several laboratories (Gowland & Stedman, 1981;Bennett, Brown, Maya, & Posey, 1982). Hydroxylammonium ion is the major hydroxylamine species in solutions with a pH lower than about 5.8 and will be the major species in the highly acidic process solutions.…”

“…Reaction (3) is key in determining the stability of HANeHNO 3 solutions as discussed above. Values for the rate constant, k 3 , have been published by a number of workers (Barney, 1971;Bennett et al, 1982;Pembridge & Stedman, 1979). Measurements have been made in both nitric acid and perchloric acid solutions at ionic strengths of 0.1e6.0 M and temperatures of 0e50 C. The mechanism for this reaction appears to change above approximately 2.0 M ionic strength.…”

“…Activation energies for Reaction (3) have been published in Gowland and Stedman (1981), Bennett et al (1982) and Barney (1971). A value of 41.5 kJ mol À1 is used in the model to predict the dependency of k 3 on temperature.…”

“…The two different sources of k 8 values are in reasonably good agreement, although the slopes of the lines are slightly different. The decomposition data yield a fitted equation that predicts k 8 values over a wide range of acid and HAN [Bennett et al (1982): 25 C in HNO 3 eLiNO 3 mixtures and Barney (1971): 30 C in HNO 3 eNaNO 3 mixtures]. concentrations and temperatures.…”