Simultaneous Removal of NO and SO2 from Flue Gas by Ozone Oxidation and NaOH Absorption

Exhaust flue gas from fossil fuel combustion usually contains a large quantity of SO 2 and NO. In this paper, a process of simultaneous removal of NO and SO 2 by ozone oxidation combined with NaOH absorption was chosen. The main investigations involved O 3 decomposition, factors affecting NO oxidation (O 3 dosage, reaction temperature, NO initial concentration, and presence of SO 2 ), and NaOH absorption. The results indicated O 3 decomposition rate increased as temperature rose and was less affected by initial concentration of O 3 . The optimal temperature for NO oxidation was 150 °C. NO oxidation efficiency increased with the increase of O 3 dosage at a fixed temperature. NO initial concentration and the presence of SO 2 had a slight effect on NO oxidation. The NO oxidation efficiency remained above 90% when n O 3 / n NO was 1. Absorption by NaOH solution resulted in the final removal of above 99% NO, 90% NO 2, and nearly 100% SO 2 at pH above 11.