We have determined that Na2O2 solution is very effective as an absorption solution for NOx removal at extremely low concentrations of NOx. In order to attain Environmental Quality Standard (EQS) for NOx by regulating only NOx from stationary and mobile emmission sources the regulation must be very severe.
The regulation will be desirable when, in addition to the emission source regula-tion, one removes NOx only in areas having very high concentrations locally higher than the EQS.
The absorption efficiency of NOx depends on the concentration of both H2O2 and NaOH in the solution.
Concentrations higher than 2g H2O2/l and 8g NaOH 1/l were needed.
We conducted experiments using a small apparatus, which had absorption units with glass fiber cloths set up parallel to the sample gas flow and in which the Na2O2 solution was circulated and sprinkled over the units. The Na2O2 solution containing H2O2 higher than 5g/l abruptly lowered the absorption efficiency when the NaOH concentration became lower than 12g/l NaOH was consumed by reaction with CO2 to form Na2O2 and NaHCO3 and the absorption efficiency gradually decreased. The absorption power significantly by using two units, one for CO2 absorption and the other for NOx.
