OES analysis in a nonthermal plasma used for toxic gas removal: Rotational and excitation temperature estimation

Nonthermal plasma technologies are often used for cleaning toxic gases. In this work, we will present an optical emission spectroscopy (OES) study in a dielectric barrier discharge (DBD) used to remove NO x specifically. Rotational temperatures are calculated from the UV-OH band (A 2Σ, ν = 0 → X 2Π ν′ = 0) situated between 306–310 nm; for the rotational temperature, a fitting method was employed (comparison between experimental data with a synthetic molecular spectrum). Excitation temperatures were calculated using OII atomic lines situated in a wavelength range of 300–700 nm using a Boltzman’s plot method. From calculated temperatures, a thermal inequity characteristic of nonthermal plasma discharges has been high-lighted. The influence of the percentage of water added to the DBD reactor is also studied in the removal efficiency and in the OH band intensities and temperatures.