Analysis of SO2 Removal and Ammonium Sulfate Particle Growth in Dielectric Barrier Discharge−Photocatalyst Hybrid Process

Abstract

We analyzed SO2 removal and ammonium sulfate particle growth in the dielectric barrier discharge−photocatalyst hybrid (DBD−PH) process. The DBD−PH reactor consists of two zones: the first for plasma generation and SO2 conversion and the second for ammonium sulfate particle formation and growth. In this work, the first zone was packed with TiO2-coated glass beads used as a dielectric material. The UV light generated from the plasma discharge activates the TiO2 photocatalyst, and the SO2 removal efficiency increases as a result of the reactive radicals generated by plasma reactions and TiO2 photocatalyst. In this work, the SO2 removal efficiency was found to increase as the applied peak voltage, residence time, and pulsed frequency increased and as the initial SO2 concentration decreased. In the DBD−PH process, gaseous SO2 is converted into H2SO4 and, upon addition of NH3, into solid (NH4)2SO4 particles, which can be separated by particle collectors. Using the second zone of the reactor, we examined (NH4)2SO4 particle growth as a function of reactor length for various process conditions. We found that the (NH4)2SO4 particles grow by particle coagulation and surface reaction along the reactor and that larger particles are produced as the residence time or initial SO2 concentration increases. This study can be a basis for the design of more efficient particle collectors in the DBD−PH process for SO2 and NO removal.