Analytical Sciences


Abstract − Analytical Sciences, 20(12), 1759 (2004).

Mechanism of the NO2 Conversion to NO2- in an Alkaline Solution
Xinyu CHEN, Kenji OKITSU, Norimichi TAKENAKA, and Hiroshi BANDOW
Department of Applied Materials Science, Graduate School of Engineering, Osaka Prefecture University, 1-1 Gakuen-cho, Sakai, Osaka 599-8531, Japan
The reaction of NO2 and NaOH aqueous solution at room temperature was studied for elucidating the behavior of gaseous NO2 in an alkaline solution. Experimental runs related to NO2 absorption have been carried out in various pH solutions. The nitrite and nitrate ions formed in these absorption solutions were quantitatively analyzed. In the case of pH 5 - 12, both of the nitrite and nitrate ions were formed simultaneously. On the other hand, only the nitrite ion was formed when the pH of the absorption solution was higher than 13. In this paper, a new reaction mechanism was proposed to explain the selective formation of nitrite ion in the 10 M alkaline solution. In order to confirm the new reaction mechanism, H218O was used as part of the absorption solution for detecting oxygen gas production. The amounts of reaction products: 18O18O, 18O16O and 16O16O, were quantitatively determined. It was confirmed that the new reaction proceeds mainly in the 10 M alkaline solution.