Aqueous Absorption and Oxidation of Nitric Oxide with Oxone for the Treatment of Tail Gases: Process Feasibility, Stoichiometry, Reaction Pathways, and Absorption Rate

The absorption−oxidation of nitrogen oxides (NO x ) induced by aqueous solutions of potassium hydrogen peroxymonosulfate or oxone (2KHSO 5 ·KHSO 4 ·K 2 SO 4 ) in the absence and presence of SO 2 has been studied in a bubble column reactor operated in semicontinuous and continuous countercurrent flow modes. The influence of different process variables, such as temperature (22−55 °C), gas stream flow rate (or residence time), concentration of oxone, solution pH, feed concentrations of NO and SO 2, and the presence of O 2 and CO 2 in the feed stream on the absorption−oxidation of NO were evaluated in the semibatch flow mode. The individual and simultaneous chemistry of NO x and SO 2 removal by peroxomonosulfate (KHSO 5 ) is discussed. The effects of simultaneous mass transfer and chemical reactions in the liquid phase were also investigated with a bubble column reactor operated in the continuous countercurrent flow mode using the theory of absorption accompanied by fast pseudo- m th-order reaction. The rate of reaction of NO with peroxomonosulfate (HSO 5 - ) was found to be first order with respect to NO and zeroth order with respect to HSO 5 - ( r A = k mn C NO ). After considering mass transfer, the rate of absorption of NO (mol/s·cm 3 ) in 0.01−0.02 M HSO 5 - at room temperature (23 ± 2 °C) was determined to be R A = P A [1.482 × 10 7 + 1/ aH ( k mn D A ) 0.5 ] -1 . The results demonstrate the feasibility of removing NO x and SO x simultaneously by low-temperature aqueous scrubbing.