Absorption of dilute NOx into nitric acid solutions containing hydrogen peroxide

Absorption of NOx, diluted with nitrogen up to concentrations of 5000 ppm, was performed at 20 degrees C and 1 atm into aqueous and nitric acid solutions containing H2O2. The absorption rate was determined for various NOx oxidation ratios in the gas phase, and for different concentrations of nitric acid and hydrogen peroxide in the scrubbing liquid. It was found that hydrogen peroxide prevents the HNO2 decomposition, which increases the overall absorption rate. The absorption efficiency remains constant if increasing excess quantities of H2O2 are used. Furthermore it was shown that nitric acid enhances considerably the absorption rate of NOx into H2O2 and that absorption of dilute NOx becomes possible in fairly concentrated nitric acid solutions. Measurements made in various conditions revealed that the specific consumption of H2O2 is stoichiometric with respect to the reaction scheme involving the different NOx species.