Simultaneous Removal of SO(2) and NO(x) Using Steel Slag Slurry Combined with Ozone Oxidation

[Image: see text] In this work, steel slag slurry was used in combination with O(3) oxidation for the simultaneous removal of SO(2) and NO(x) in a laboratory-scale wet flue gas desulfurization process. The effects of the oxidation temperature, steel slag concentration, initial SO(2) concentration, and pH value on the desulfurization and denitrification efficiencies were studied. The results showed that the highest NO(x) removal efficiency occurred at an oxidation temperature of 90 °C. With an increase of the oxidation temperature above 90 °C, the denitrification efficiency decreased due to the decomposition of N(2)O(5). The effect of the SO(2) concentration on denitrification was complicated. When the concentration of SO(2) was 500 ppm, generation of SO(3)(2–) promoted the absorption of NO(2). However, higher SO(2) concentrations strengthened the competitive absorption of SO(2) and NO(x). In the pH range of 8.5–4.5, the denitrification efficiency was maintained at about 96%. The component analyses of the aqueous solution and the solid residue were conducted to investigate the compositions of the absorption products. The results showed that NO(3)(–) and SO(4)(2–) were the major anions in the aqueous solution. The nitrogen balance was analyzed to be 95.8%, clearly illustrating the migration and transformation path of nitrogen. In the solid residue, most alkaline substances were consumed, and the final products were mainly CaSO(4) and FeO. Accordingly, the reaction mechanism of simultaneous desulfurization and denitrification using steel slag combined with ozone oxidation was proposed.