Nitric oxide scavenging of hydroxyl radicals in a nanosecond pulsed plasma discharge gas–liquid reactor

A continuous gas-liquid film flow reactor with a nanosecond power supply was utilized to produce NO2-, NO3-, and NO2 from Ar/NO mixtures (gas phase) and deionized water (liquid phase). High concentrations of added NO were used as an center dot OH scavenger and to provide insight into the reaction pathways. Chemical analysis of the products exiting the reactor was performed by quenching the liquid samples to eliminate the post-plasma reactions. The gas phase products were analyzed using FTIR and the liquid phase samples were analyzed using ion chromatography and UV-vis spectrophotometer. The concentrations of NO2-, NO3- and NO2 increased with increasing inlet concentrations of NO while the concentration of H2O2 decreased moderately. The plasma gas temperature was approximately 565 K and was unaffected by the NO feed concentration, while the electron density varied from 4.83 x 10(16) cm(-3) to 1.16 x 10(17) cm(-3) for inlet NO concentrations of 0 ppm to 20000 ppm, respectively. The increase in NO2 concentration in the gas phase suggests that center dot OH provides a source of atomic oxygen (O). The results also suggest that center dot OH plays an important role in the formation of HNO2 and HNO3 by directly reacting with NO and NO2, respectively. The highest production rate of center dot OH was 6.5 x 10(-6) moles s(-1) at 20 000 ppm inlet NO. The energy yield of center dot OH was 5.7 x 10(-7) moles J(-1) at 20000ppm inlet NO and is in agreement with our previous work and other literature reports.