Bromomethane Decomposition Using a Pulsed Dielectric Barrier Discharge

The decomposition of bromomethane (CH₃Br), which is an ozone-depleting substance, is carried out using a pulsed dielectric barrier discharge. To accomplish this, a plasma reactor comprising a stainless discharge wire electrode and a quartz cylinder wrapped with a copper mesh as the ground electrode is employed. This reactor is energized by a pulsed high-voltage power supply using an insulated-gate bipolar transistor. The effects of humidity, flow rate, and initial CH₃Br concentration on CH₃ Br decomposition are investigated. The relative humidity is found to slightly affect the CH₃Br decomposition. Additionally, the CH₃Br decomposition efficiency is found to decrease with increasing gas flow rate; however, the amount of decomposed CH₃Br increases with gas flow rate. More than 95% CH₃Br decomposition efficiency is achieved at a gas flow rate of 1 L/min and initial CH₃Br concentrations of 1000, 5000, and 10 000 ppm. Gas chromatography/mass spectroscopy analysis shows that approximately 95% of the decomposed CH₃Br is converted to HBr, which can be easily removed using an alkaline scrubber. The energy efficiency of the CH₃Br decomposition increases with the initial concentration at the same specific energy. In addition, the specific energy decreases when the energy efficiency is maintained by increasing the gas flow rate.