Additive Effect of Water on the Decomposition of VOCs in Nonthermal Plasma

In the removal of volatile organic compounds (VOCs) with nonthermal plasma (NTP), gaseous oxygen is mandatory to oxidatively decompose VOCs. On the other hand, there have been disputed discussions on the additive effect of water in the decomposition of VOCs in NTP, but a unified mechanism has not been established yet. Both of VOC conversion and carbon balance can be affected by plasma reactor type, relative concentration of water, and gas temperature. Hence, the additive effect of water on the NTP decomposition of dichloromethane, toluene, and methanol was examined in the range of water content from 0.0 to 2.0 % at temperatures of 298 and 373 K. Consequently, it has been shown that no rate-promoting effect of water has been observed in the conversion of dichloromethane, toluene, or methanol from 0.5 to 2.0 % of water content, and water addition increased CO₂ selectivity and improved carbon balance to different degrees, depending on the chemical structure of these VOCs.