Removal of sulfur dioxide from air using a packed-bed DBD plasma reactor (PBR) and in-plasma catalysis (IPC) hybrid system

Sulfur dioxide, a noxious air pollutant, can cause health and environmental effects, and its emissions should be controlled. Nonthermal plasma is one of the most effective technologies in this area. This study evaluated the efficiency of a packed-bed plasma reactor (PBR) and in-plasma catalysis (IPC) in SO₂ removal process which were finally optimized and modeled by the use of the central composite design (CCD) approach. In this study, SO₂ was diluted in zero air, and the NiCeMgAl catalyst was selected as the catalyst part of the IPC. The effect of three main factors and their interaction were studied. ANOVA results revealed that the best models for SO₂ removal efficiency and energy yielding were the reduced cubic models. According to the results, both PBR and IPC reactors were significantly energy efficient compared with the nonpacked plasma reactor and had high SO₂ removal efficiency which was at least twice larger than that of the nonpacked one. Based on the results, the efficiency of IPC was better than in PBR, but its performance decreased over time. However, the PBR had relatively high SO₂ removal efficiency and energy efficiency compared to the nonpacked reactor, and its performance remained constant over the studied time. In optimization, the maximum SO₂ removal efficiency and energy efficiency were 80.69% and 1.04 gr/kWh, respectively (at 1250 ppm, 2.5 L/min, and 18 kV as the optimum condition) obtained by the IPC system which were 1.5 and 1.24 times greater than PBR, respectively. Finally, the model's predictions showed good agreement with the experiments.