Pulse radiolytic investigations of aqueous solutions of methoxybenzene cation radicals: the effect of colloidal RuO/sub 2/
The formation and decay of the radical cations of 1,4-dimethoxybenzene (DMB) and 1,2,4,5-tetramethoxybenzene (TMB) were investigated by the pulse radiolysis technique in the absence and the presence of colloidal RuO/sub 2/ particles. DMB/sup +/ was obtained only by Tl/sup 2 +/ oxidation of DMB while TMB/sup +/ was produced by oxidation of TMB using both Tl/sup 2 +/ and Br/sub 2//sup -/. In the absence of RuO/sub 2/ both DMB/sup +/ and TMB/sup +/ decay predominantly via a second-order process, although there is a contribution of a pseudo-first-order reaction. The rate constants for these reactions are reported. RuO/sub 2/ colloidal particles catalyze the decay of both TMB/sup +/ and DMB/sup +/. The reactions of TMB/sup +/ with RuO/sub 2/ were found to depend on pH, pulse intensity, and colloid concentration. At pH 3-4, adsorption of TMB/sup +/ to the colloid is observed, followed by the decay of the remaining TMB/sup +/ in the bulk. At higher pHs, loading of the RuO/sub 2/ colloid by positive holes takes place until equilibrium is achieved between loaded holes and TMB/sup +/ and again the remaining TMB/sup +/ decays at a later stage. The fraction of TMB/sup +/ that loads the colloidal particles increases with both pH and (RuO/sub 2/). It is also suggested that DMB/sup +/ loads the RuO/sub 2/ at the pH where experiments were performed. (TMB)/sub 2/ and (DMB)/sub 2/ dimers (or higher oligomers) are suggested to be the final products both in the absence and presence of RuO/sub 2/. No O/sub 2/ is formed with the RuO/sub 2/ colloid despite a favorable redox potential for water oxidation.
- Research Organization:
- Hebrew Univ. of Jerusalem, Israel
- OSTI ID:
- 7042009
- Journal Information:
- J. Phys. Chem.; (United States), Vol. 91:4
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ANISOLE
RADIOLYSIS
AQUEOUS SOLUTIONS
CATIONS
CHEMICAL REACTION KINETICS
COLLOIDS
EXPERIMENTAL DATA
PH VALUE
PULSE TECHNIQUES
REDOX POTENTIAL
RUTHENIUM OXIDES
CHALCOGENIDES
CHARGED PARTICLES
CHEMICAL RADIATION EFFECTS
CHEMICAL REACTIONS
CHEMISTRY
DATA
DECOMPOSITION
DISPERSIONS
ETHERS
INFORMATION
IONS
KINETICS
MIXTURES
NUMERICAL DATA
ORGANIC COMPOUNDS
ORGANIC OXYGEN COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
RADIATION CHEMISTRY
RADIATION EFFECTS
REACTION KINETICS
REFRACTORY METAL COMPOUNDS
RUTHENIUM COMPOUNDS
SOLUTIONS
TRANSITION ELEMENT COMPOUNDS
400600* - Radiation Chemistry