scispace - formally typeset
Search or ask a question

Showing papers on "Chromium(III) oxide published in 1987"




Journal Article
TL;DR: In this article, an unreacted core shrinking model with ash diffusion control was found to predict the dissolution behavior of chromium(III) oxide particles satisfactorily in the experimental error range.
Abstract: Chromium oxide, amounting to about 40% of the total corrosion oxides formed within the primary coolant system of Pressurized Water Reactor, can be removed by an oxidative dissolution. The study of dissolution reaction of chromium(III) oxide was carried out with a stirred batch-type dissolver under constant concentration and temperature of bulk phase during the reaction using relatively small amount of chromium(III) oxide particles and dilute nitric acid/permanganate solution. An unreacted-core shrinking model with ash diffusion control was found to predict the dissolution behaviour of chromium(III) oxide particles satisfactorily in the experimental error range. Overall dissolution reaction rate constant of the above model, , being inversely proportional to the bulk phase concentration while being proportional to hydrogen ion concentration and temperature, was expressed by the following experimental correlation within the experimental range.

1 citations


Journal ArticleDOI
TL;DR: In this article, a detailed study of the oxidative dissolution of chromium(III) oxide (Cr2O3) in potassium permanganate is reported, and the kinetics of the reaction follow an inverse-cubic rate law under both acid and alkaline conditions; no inhibition by MnO2 product is observed.
Abstract: A detailed study of the oxidative dissolution of chromium(III) oxide (Cr2O3) in potassium permanganate is reported. The kinetics of the reaction follow an inverse-cubic rate law under both acid and alkaline conditions; no inhibition by MnO2 product is observed. In alkaline solution, in the temperature range 43–140 °C, the rate exhibits dependences on permanganate and hydroxide concentrations which are explained in terms of a Langmuirian adsorption mechanism. The rate of dissolution is controlled by electron transfer within a surface complex in which both OH– and MnO–4 are bound. Thermodynamic parameters imply chemical bond formation between permanganate and ions in the oxide surface. A study in dilute HNO3 shows that adsorption of MnO–4 is also a prerequisite for reaction under acid conditions.