Dielectric Barrier Discharge of Moist Nitrogen: A Methodology for Exclusive NO Generation

Abstract

Chemical transformations of moist nitrogen in dielectric barrier discharge cold plasma into NO, NO2, and NO2− in conjunction with the control for exclusive NO generation are reported. Initial gas-phase products NO and NO2 were identified and estimated spectrophotometrically at respective absorption $\lambda _{{{\text {max}}}}$ taking the set of three closely spaced peaks around 204, 214.5, and 226 nm in case of the former, while at 400 nm for latter. Other products NO2− and H2O2 were identified and estimated by wet-chemical sampling methods followed by colorimetric analyzes, respectively, at 540 and 350 nm. NO, NO2, and NO2− yields increased continuously, with increase in gas residence time inside the plasma zone, applied voltage between two electrodes, and the moisture concentration in the gas stream. Typical G values estimated are: NO, $3.98 \times 10^{-3}$ ; total NO2 and NO2−, $6.30 \times 10^{-3}$ ; and H2O2, $2.7 \times 10^{-3}~\mu \text {mol}\cdot \text {J}^{-1}$ . In the product mixture, employing NO2 and NO2− absorber solution, 50–750 ppm level NO was obtained as an exclusive product with 0.05–24 kHz ac power supplies.