Generation of reactive oxygen species in simulated flue gas under vacuum ultraviolet radiation

• We determine reactive oxygen species in simulated flue gas under VUV radiation.
• We examine the effects of H2O content, O2 content, flow rate and VUV lamp power.
• Increasing O2 content and flow rate will increase O3 production.
• Increasing H2O content and flow rate will increase H2O2 production.
• Increasing lamp power will affect O3 production slightly but decrease H2O2 production.

Reactive oxygen species, which are responsible for the removal of SO2 and NOx, generated under vacuum ultraviolet (VUV) radiation in simulated flue gas (N2/O2/CO2/H2O (v/v) = 74%/8%/10%/8% without SO2 and NOx) were determined. Under typical experimental conditions, 26.5 μmol ozone, 1.7 μmol hydrogen peroxide, and 0.3 μmol hydroxyl radical were detected. The effects of H2O and O2 contents, gas flow rate, and lamp power on the generation of reactive oxygen species were investigated. Results show that H2O and O2 contents as well as flow rate significantly affected O3 and H2O2 production. High content of H2O resulted in a decrease in O3 production but an increase in H2O2 production, whereas O2 content demonstrated the opposite effects owing to its varying absorption across sections. O3 and H2O2 production increased with increasing flow rate, while their concentrations changed slightly. High-power lamps had a negligible effect on O3 and H2O2 production, but O3 production decreased and H2O2 production increased under extremely low-power lamp radiation. In addition, the variations of the production of reactive oxygen species were also correlated with the oxidation processes of VUV-induced simultaneous desulfurization and denitrification.