Steady state and pulse radiolysis studies of molybdenum octacyanate in aqueous solutions
The oxidation of oxygen saturated solutions of Mo(CN)/sub 8//sup 4 -/ at different pH values was studied by steady state and pulse radiolysis techniques. It was shown that Mo(CN)/sub 8//sup 3 -/ is the oxidation product formed. G values of the Mo(V) octacyanate varied with the pH of the solution. It was of the order of 13 at pH 0(1 M HClO/sub 4/) and approaching zero at pH > 7. The high G values in acid solutions are explained by the oxidation of the Mo(IV) complex ion in the reactions with OH and HO/sub 2/ radicals and by H/sub 2/O/sub 2/. The H/sub 2/O/sub 2/ reaction with Mo(IV) ion was found to be a very slow reaction and 75 percent effective only. In neutral and alkaline solutions the low G values are interpreted by the reduction of the Mo(V) ions formed by the O/sub 2/- radicals. Confirmation of the above mechanism was established by using the pulse radiolysis technique. The formation of Mo(CN)/sub 8//sup 3 -/, the oxidation product of Mo(CN)/sub 8//sup 4 -/ in the reactions with OH and HO/sub 2/ radicals, was followed at 385 nm. The rate constants (in M/sup -1/ s/sup -1/) are (5.8 +- 0.5) x 10/sup 9/ and (5.7 +- 0.6) x 10/sup 4/, respectively. These values were unaffected by the presence of H/sup +/ or unreactive alkaline cations. O/sup -/ reacts with Mo(CN)/sub 8//sup 4 -/ much more slowly (estimated to be approximately 1 x 10/sup 7/ M/sup -1/ s/sup -1/). O/sub 2//sup -/ reduces the Mo(CN)/sub 8//sup 3 -/ to Mo(CN)/sub 8//sup 4 -/, the rate constant found was 3.0 +- 0.5 x 10/sup 5/ M/sup -1/ s/sup -1/.
- Research Organization:
- Nuclear Research Centre-Negev, Beersheba, Israel
- OSTI ID:
- 7139928
- Journal Information:
- J. Phys. Chem.; (United States), Vol. 80:21
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
MOLYBDENUM COMPLEXES
RADIATION CHEMISTRY
AQUEOUS SOLUTIONS
CHEMICAL REACTION KINETICS
CYANATES
G VALUE
GAMMA RADIATION
HYDROXYL RADICALS
IRON COMPLEXES
OXIDATION
PEROXY RADICALS
PH VALUE
CARBONIC ACID DERIVATIVES
CHEMICAL REACTIONS
CHEMISTRY
COMPLEXES
DISPERSIONS
ELECTROMAGNETIC RADIATION
IONIZING RADIATIONS
KINETICS
MIXTURES
NITROGEN COMPOUNDS
ORGANIC COMPOUNDS
RADIATIONS
RADICALS
REACTION KINETICS
SOLUTIONS
TRANSITION ELEMENT COMPLEXES
400600* - Radiation Chemistry