Simultaneous absorption of NO and NO2 into alkaline solutions.

Abstract

Simultaneous absorption of NO2 and NO into alkaline solutions was studied in a wide range of gaseous concentrations, NO2 from 5 to 2000 ppm and NO from 0.066 to 1.2%. The absorption rate was not dependent on the concentration of hydroxide ion in the solution, if the alkalinity in the vicinity of the interface was maintained. In the presence of NO in excess of NO2, the stoichiometry of the absorption is expressed by the reaction NO+NO2+2OH-→2NO2-+H2O and the rate is proportional to the product of the interfacial concentrations of NO2 and NO. The predominant mechanism is considered to be the solution of N2O3 in equilibrium with NO and NO2 at the interface followed by its rapid hydration. The absorption rate is expressed by H√k2D [N2O3]G, H√k2D being 2.55 m•s-1, which is about two orders of magnitude greater than the corresponding value for the absorption of N2O4.