Abatement of VOCs by Cold Atmospheric Air Plasma at Low Temperature and Ambient Pressure

Volatile organic compounds (VOCs) emitted from various industrial processes are extremely harmful pollutants. They are involved in forming ozone, photochemical smog, and fine particles (PM_2.5) in the atmosphere, which pose a considerable threat to human health and ecosystem safety. The hybrid plasma-catalytic technology is an efficient method for VOC abatement. In this work, a coaxial dielectric barrier discharge (DBD) based non-equilibrium cold plasma source powered by a bipolar pulse power source is reported for effective decomposition of VOCs in an enclosed region at low temperature (< 50°C) and ambient pressure. The decomposition efficiency of VOCs is, in general, controlled via the specific input energy, which mainly depends on the flow rates of treated VOCs, but here we report the synergistic effect of highly energetic electrons and reactive species on the decomposition process. The excited species are analyzed using optical emission spectroscopy. The electron temperature and particle density measurements have also been carried out using the recorded spectra and line intensity ratio technique. For about 60 minutes of continuous operation of the plasma source, a decomposition efficiency of 99.7% (toluene) and 74.8% (benzene) is achieved. The developed source produces powerful, immediate discharge and energetic electrons, which have been efficiently used for VOC degradation. Results are useful for applying non-equilibrium cold plasmas in an enclosed region containing numerous VOCs.