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The oxidation of water and inorganic nitrogen compounds by potassium ferrate (VI)
Abstract
The oxidations of azide, hydroxylamine, hydrazine, and ammonia by potassium ferrate(VI) were investigated in aqueous solutions from neutral to basic pH conditions. The study included both reaction kinetics and product determination. The rate of disappearance of the ferrate(VI) ion was monitored spectrophotometrically at 505 nm using both stopped-flow and conventional instruments. The analytical techniques of gas chromatography, ion chromatography, and differential pulse polarography were used to identify and quantitate the products of these reactions. Dinitrogen, nitrous oxide, nitrite, and nitrate were the most often encountered nitrogen-containing products from these oxidations. A mass balance between the products formed and the ferrate(VI) reacted was calculated for each reductant. Based on the kinetic results and the product analysis data, the order of reactivity of these solutes toward ferrate(VI) at pH 10 is: N$\sb2$H$\sb4$ $>$ NH$\sb2$OH $\gg$ NH$\sb3$ $>$ N$\sb3\sp-$. At pH 7, the reactivity order is: N$\sb2$H$\sb5\sp+$ $>$ NH$\sb2$OH $\approx$ N$\sb3\sp-$ $\gg$ NH$\sb4\sp+$. A mechanism is proposed for each of these reactions which is consistent with the kinetic data and the product distributions. The reactive species nitroxyl (HNO or NO$\sp-$) is suggested as a likely intermediate in a number of the proposed mechanisms. In addition, the stoichiometry and products from the oxidation of solvent water by the ferrate(VI) in the pH range from 4 to 8.5 was reinvestigated. Gas chromatography and differential pulse polarography were used to determine the products of the reaction. Molecular oxygen is found to be the major product of this oxidation with small amounts of hydrogen peroxide also detected. A mechanism has been proposed by which these products are formed.
Subject Area
Chemistry|Analytical chemistry
Recommended Citation
Erickson, John Edward, "The oxidation of water and inorganic nitrogen compounds by potassium ferrate (VI)" (1988). ETD collection for University of Nebraska-Lincoln. AAI8911108.
https://digitalcommons.unl.edu/dissertations/AAI8911108