Generation of Nitrous Acid by Ultrasound Irradiation in the Organic Solution Consisting of Tri-n-butylphosphate, Nitric Acid and Water

摘要

The generation of nitrous acid (HNO_2) by ultrasound was investigated for an organic solution consisting of tri-n-butylphosphate, nitric acid (HNO_3) and water under several conditions. The amount of HNO_2 was found to increase by a factor of 40 upon ultrasound irradiation, and the concentration of HNO_2 reached the steady-state after long time irradiation. Although the concentration of HNO_3 was low, the rate of generation of HNO_2 in the organic solution was higher than that in aqueous solution equilibrated with the organic solution. The formation rates of HNO_2 were greatly enhanced with an increase in concentration of HNO_3 in the organic solution. The concentration of HNO_2 was higher in the absence of a gas phase, because the HNO_2 was transferred from the solution into the gas phase as a form of NOx. In the presence of a gas phase, a higher concentration of HNO_2 was obtained at a lower temperature, due to the higher solubility of NOx in the solution.