Simultaneous Absorption and Oxidation of Nitric Oxide and Sulfur Dioxide by Aqueous Solutions of Sodium Persulfate Activated by Temperature

The absorption-oxidation of nitrogen oxide (NO) induced by aqueous solutions of sodium persulfate (Na2S2O8) in the presence of SO2 has been studied in a bubble column reactor operated in semibatch mode. The effects of Na2S2O8 concentration (0.01-0.20 M), temperature (23-70 degrees C), 1550 ppm gas-phase SO2, and solution pH on NO removal (1000 ppm gas-phase concentration) were investigated. The presence of SO2 dramatically improved NO gas absorption and oxidation while it was itself completely removed. The NO fractional conversions in the presence of SO2 ranged from 77% to 83%, with the greatest effect occurring at lower temperatures (23 and 30 degrees C). While persulfate concentration of 0.1 M appeared optimal for aqueous NO removal, both in the absence and presence of SO2, significant improvements in NO removal were observed for persulfate concentrations of >0.05 M but antagonistic effects were observed with concentrations of <0.05 M in the presence of SO2, compared to without SO2. The pH range of 6.5-8.5 appears to be ideal for NO removal in the presence of SO2. The individual and simultaneous chemistry of NOx and SO2 removal by persulfate is discussed. The results demonstrate the feasibility of removing NOx and SOx simultaneously by aqueous scrubbing.