Analysis of SO₂ removal and ammonium sulfate particle growth in dielectric barrier discharge-photocatalyst hybrid process

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 SO ₂ 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 SO ₂ 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.