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 °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 °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 NO x and SO2 removal by persulfate is discussed. The results demonstrate the feasibility of removing NO x and SO x simultaneously by aqueous scrubbing.

Nitric oxide (NO) removal by aqueous sodium persulfate (Na2S2O8) simultaneously activated by temperature and Fe2+ was studied in a lab-scale bubble reactor. The effects of Na2S2O8 (0.01–0.20 M), Fe2+ (0.00–0.10 M), gas-phase NO (500–1000 ppm) concentrations, and temperatures (23–90 °C) were investigated. NO fractional conversion at all temperatures with and without the presence of Fe2+ increased sharply with persulfate concentration up to about 0.10 M before leveling off. At 0.10 M Na2S2O8 and 0.01 M Fe2+ concentrations, conversions of up to 79% and approximately 100% were observed at 70 and 90 °C, respectively. Increased temperature led to increased conversions of NO at all persulfate levels, and activation by 0.01 M Fe2+ further improved NO conversion by ∼10% at all temperatures. The chemistry of NO removal and proposed reaction pathways are discussed. The results demonstrated the feasibility of improved NO aqueous scrubbing by temperature- and Fe2+-activated persulfate.

The chemistry and kinetics of NO removal by aqueous solutions of sodium persulfate (Na 2 S 2 O 8 ) simultaneously activated by temperature and Fe 2+ were studied in a bubble reactor. Reaction pathways were proposed and a mathematical model utilizing the pseudo-steady-state-approximation technique and film theory of mass transfer were developed. The model was solved numerically using the fourth order Runge−Kutta method in Matlab to obtain species concentrations; correlate experimental data; and estimate mass transfer and kinetic rate parameters. The model was used to investigate the effects of Na 2 S 2 O 8 (0.01−0.2 M), Fe 2+ (0−0.1 M), gas-phase NO (500−1000 ppm) concentrations and temperatures (23−90 °C), and is a follow-up to an experimental study, which demonstrated that Fe 2+ activation further improved NO conversion by ∼10% at all temperatures. The model results, which appeared to fit those of the experiments remarkably well, were discussed and predicted kinetic data compared with available literature values.

No abstract