Technical NotePhotolysis of low concentration H2S under UV/VUV irradiation emitted from high frequency discharge electrodeless lamps

- The photolysis of low concentration of H2S malodorous gas.
- Self-made high frequency discharge electrodeless lamp.
- Effects of relative humidity and gas environments.
- Mechanisms for direct and indirect photolysis (ozone and radical generation).

The photolysis of low concentration of H2S malodorous gas was studied under UV irradiation emitted by self-made high frequency discharge electrodeless lamp with atomic mercury lines at 185/253.7 nm. Experiments results showed that the removal efficiency (ηH2S) of H2S was decreased with increasing initial H2S concentration and increased slightly with gas residence time. ηH2S was increased dramatically with relative humidity from <5% to 43% while the concentration of oxygen in gas environments affected the removal of H2S. The mechanisms for direct and indirect photolysis (generation of ozone) were illustrated by the experimental results on photolysis of H2S under argon environments and ozonation of H2S under air environments, respectively. The overall ηH2S by photolysis is higher than the combination of ηH2S by direct photolysis and ozonation, suggesting that hydroxyl radical-mediated indirect photolysis played an important role during photolysis processes. The main photolysis product was confirmed to be SO42- with ion chromatograph.