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Chain processes in the Tc(VII)-catalysed oxidation of hydrazine by nitrate and perchlorate ions
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Thyer, Aubrey Maurice (1990) Chain processes in the Tc(VII)-catalysed oxidation of hydrazine by nitrate and perchlorate ions. PhD thesis, University of Warwick.
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Official URL: http://webcat.warwick.ac.uk/record=b3224438~S15
Abstract
Studies of the reaction between pertechnetate ion and hydrazine in solutions in several different acids have been carried out In order to establish the reaction mechanism and, where possible, the Individual rate constants of each step. Computer simulation of the experimental data has been utilised to enable the formulation of reaction schemes for these very complex chain reactions.
In nitric acid the reaction typically exhibits an Induction period of variable length depending on the acidity and concentrations of nitrate, hydrazine and technetlium. This is followed by a stage of rapid loss of hydrazine from the solution due to its oxidation by TcVI, while the TcIV produced is re-oxidised to TcVI by nitrate. The termination step is considered to be the acid-catalysed oxidation of TcVI to TCO4- by nitrate. The effect of increasing acidity is to Increase the length of the induction stage and to decrease the rate of hydrazine oxidation during the fast reaction stage: this causes the reaction to be terminated with increasingly greater residual concentrations of unoxidized hydrazine: at 5 aol da-3 HN03 no loss of N2h4 from the solution is observed.
Replacing nitric acid by acids such as HCIO4, HBF4, HC1 or CF3COOH shows that nitric acid Is unique in Its inhibiting effect on the hydrazine destruction reaction. In the presence of these acids the length of the Induction stage is decreased, and the rate of the fast reaction stage is increased, with increasing acidity, i.e. in direct contrast to the situation for HNO3 media.
Item Type: | Thesis (PhD) | ||||
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Subjects: | Q Science > QD Chemistry | ||||
Library of Congress Subject Headings (LCSH): | Hydrazine, Nitrates, Perchlorates, Nitric acid | ||||
Official Date: | 1990 | ||||
Dates: |
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Institution: | University of Warwick | ||||
Theses Department: | Department of Chemistry | ||||
Thesis Type: | PhD | ||||
Publication Status: | Unpublished | ||||
Supervisor(s)/Advisor: | Kemp, T. J. (Terence James), 1938- | ||||
Sponsors: | Science and Engineering Research Council (Great Britain) ; British Nuclear Fuels (Firm) | ||||
Extent: | various : illustrations, charts | ||||
Language: | eng |
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