Efficient removal of benzene in air at atmospheric pressure using a side-on type 172 nm Xe₂ excimer lamp

The photochemical removal of benzene was studied in air at atmospheric pressure using a side-on type 172 nm Xe₂ excimer lamp with a wide irradiation area. After 1.5 min photoirradiation, C₆H₆ (1000 ppm) in air was completely converted to HCOOH, CO, and CO₂ at a total flow rate of 1000 mL/min. The initial decomposition rate of C₆H₆ was determined to be 1.18 min^-1. By using a flow system, C₆H₆ (200 ppm) was completely removed at a total flow rate of 250 mL/min. The conversion of C₆H₆ and the energy efficiency in the removal of C₆H₆ changed in the 31-100% and 0.48-1.2 g/kWh range, respectively, depending on the flow rate, the O₂ concentration, and the chamber volume. On the basis of kinetic model simulation, dominant reaction pathways were discussed. Results show that the O(³P) + C₆H₆ reaction plays a significant role in the initial stage of the C₆H₆ decomposition. Important experimental parameters required for further improvement of the C₆H₆ removal apparatus using a 172 excimer lamp were discussed based on model calculations.