Efficient degradation of dichloromethane by nonthermal plasma combined with UV-activated wet scrubber

Non-thermal plasma (NTP) technology has emerged as a promising approach for the control of chlorinated volatile organic compounds (CVOCs) due to its high degradation efficiency and operational simplicity. However, practical application is constrained by secondary ozone (O₃) emissions and incomplete degradation of CVOCs to CO 2 and HCl. To address these limitations, a liquid-phase UV system was integrated downstream of the NTP reactor to convert O₃ into reactive oxygen species (ROS), thereby enhancing DCM mineralization. The results showed that the degradation efficiency (DE) and mineralization rate (MR) of DCM in the NTP+UV(L) system reached 83.5% and 73.9%, respectively, which were markedly elevated compared to those of the NTP system (DE: 17.3%, MR: 20.9%) and the UV(L) system (DE: 28.7%, MR: 36.1%). The synergistic effect in this combined system was attributed to the activation of O 3 into hydroxyl radicals (·OH) and superoxide ions (·O 2 - ) by UV light in the solution for the deep oxidation of DCM. The chlorine in DCM was converted into chloride ions (Cl - ) and trapped in the solution. Finally, the reaction pathways of DCM within the NTP+UV(L) system were inferred by detecting organic intermediates in both the gas and liquid phases. This novel combined NTP+UV(L) system represents a potential method for DCM degradation.