Dielectric barrier discharge coupled with Fe²⁺, Mn²⁺ and Cu²⁺ scrubbing for toluene removal

By-product ozone emission is one of the challenges for applying dielectric barrier discharge (DBD) technology for volatile organic compounds (VOCs) removal. In this study, a DBD reactor followed by a wet scrubber (WS) containing a solution of metal ions (Fe²⁺/Mn²⁺/Cu²⁺) was used to reuse ozone for further oxidation of typical VOC toluene. Compared with the degradation effect of the DBD reactor alone, DBD coupled WS/iron system not only improved the toluene removal efficiency but also significantly reduced the ozone emission. The ozone removal efficiency reached as high as 98% in the DBD coupled WS/Fe²⁺ system. Electron paramagnetic resonance (EPR) tests showed that ozone was converted into radicals such as hydroxyl radicals in Fe²⁺ and Cu²⁺ solution, which further oxidized toluene in WS/iron. Quenching experiments showed that the contribution for toluene degradation by radicals was up to 75% and 62% in Fe²⁺ and Mn²⁺ reactor, respectively. This study demonstrates that the DBD coupled WS system has the potential to be an environmentally friendly technology for gaseous VOCs removal.