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.