ABSORPTION OF LEAN NOX IN AQUEOUS-SOLUTIONS OF NACLO2 AND NAOH

The absorption of such lean NOx as encountered in flue gases in aqueous mixed solutions of NaCIO2 and NaOH was carried out using a stirred vessel with a plane interface at 25 °C and atmospheric pressure. The rate of NO2 absorption was analyzed by the chemical absorption theory under the fast-reaction regime. The reaction which prevailed was found to be the parallel reactions involving oxidation and hydrolysis, and to be second order with respect to NO2. The second-order rate constant for the hydrolysis was evaluated as 3.09 X 108 L/mol s. The order of reaction relative to CIO2” was derived as unity for chlorite concentrations greater than 1.0 M. The third-order rate constant for the oxidation was derived as 7.32 X 108 (L/mol)2/s at [NaOH] = 0.20 M. For the absorption of NO, there appears to be a gradual jump in absorption rate at the interfacial concentration of NO ranging from 5 X 10-7 to 2 X 10-6 mol/L. Above this transition region, the order of reaction in NO approaches 2, whereas below the transition region, the order of reaction becomes unity. © 1979, American Chemical Society. All rights reserved.