Simultaneous removal of SO2 and NO2 using a Mg–Al oxide slurry treatment

• SO2 and NO2 were simultaneously removed from a mixed gas using a Mg–Al oxide slurry.
• Comparison was made between the removal of the gases individually and simultaneously.
• It was found that the presence of the SO2 significantly affected the removal of NO2.

SO2 and NO2 were simultaneously removed from a mixed gas using a Mg–Al oxide slurry treatment. Both adsorption to the oxide material itself and dissolution of the gases in the aqueous slurry contributed to the removal. A comparison was made between removal of the two gases separately and the simultaneous process. The removal of SO2 using both the simultaneous and individual process was similar; however, the removal of NO2 was lower for the simultaneous process. For the individual treatments, SO2 and NO2 were separately dissolved in the Mg–Al oxide slurry to produce SO32-, NO2-, and NO3-, which were subsequently removed by the Mg–Al oxide. However, when the simultaneous process was employed, the dissolved gases were seen to have a significant effect on each other. It was speculated that the production of NO2- was increased by the reduction of NO2 by SO32-. On increasing the quantity of the Mg–Al oxide, or on raising the temperature of the system, the removal of SO2 increased, with a concurrent decrease in NO2 removal. The increase in removal of SO32- was speculated to hinder the conversion of NO2 to NO2-, therefore decreasing the removal of the nitrogen species. The results demonstrate that the Mg–Al oxide slurry was highly effective for simultaneously removing NO2 and SO2 from a mixed gas.