抄録
The oxidation behavior of triiodide ions (I3-) in iodine solution in contact with 12 vol% NOx gas was examined in the range from room temperature to 80°C.
Upon contact with 2 vol% NOx gas, 13- ions in the solution disappeared within 1 h, and were replaced by iodine molecules (I2) in increasing concentration. A similar suppression of I3- ions was observed also with a starting liquid phase of concentrated I3- solution. This behavior of I3- and I- ions is attributed to the oxidation of these ions in the solution into I2 molecules by HNO2 and HNO3 formed by the reaction between NO2 contained in the NOx gas-and water. The above oxidation reactions set in when the HNO3 concentration exceeds 1 N. Beyond 10 N HNO3, the I2 molecules forming part of the I3- molecular structure, appear to be further oxidized into IO3-.
The oxidation of I3- in I- aqueous solution in contact with continuously supplied 1 vol% NOx is considered to be brought about in the initial stage by HNO2, and in the succeeding stage by HNO3 after its concentration exceeds a threshold point around 1 N.
