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 (NOx) induced by aqueous solutions of potassium hydrogen peroxymonosulfate or oxone (2KHSO(5).KHSO4.K2SO4) in the absence and presence of SO2 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 degreesC), gas stream flow rate (or residence time), concentration of oxone, solution pH, feed concentrations of NO and SO2, and the presence of O-2 and CO2 in the feed stream on the absorption-oxidation of NO were evaluated in the semibatch flow mode. The individual and simultaneous chemistry of NOx and SO2 removal by peroxomonosulfate (KHSO5) 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-mth-order reaction. The rate of reaction of NO with peroxomonosulfate (HSO5-) was found to be first order with respect to NO and zeroth order with respect to HSO5- (rA = k(mn)C(NO)). After considering mass transfer, the rate of absorption of NO (mol/s.cm(3)) in 0.01-0.02 M HSO5- at room temperature (23 +/- 2 degreesC) was determined to be RA = P-A[1.482 x 10(7) + 1/alphaH(k(mn)D(A))(0.5)](-1). The results demonstrate the feasibility of removing NOx and SOx simultaneously by low-temperature aqueous scrubbing.