Oxidation of Aqueous Toluene by Gas-Phase Pulsed Corona Discharge in Air-Water Mixtures Followed by Photocatalytic Exhaust Air Cleaning

The treatment of wastewaters containing hazardous volatile organic compounds (VOCs) requires the simultaneous treatment of both water and air. Refractory toluene, extensively studied for its removal, provides a basis for the comparison of its abatement methods. The oxidation of aqueous toluene by gas-phase pulsed corona discharge (PCD) in combination with the subsequent photocatalytic treatment of exhaust air was studied. The PCD treatment showed unequalled energy efficiencies in aqueous and gaseous toluene oxidation, reaching, respectively, up to 10.5 and 29.6 g center dot kW(-1)center dot h(-1). The PCD exhaust air contained toluene residues and ozone in concentrations not exceeding 0.1 and 0.6 mg center dot L-1, respectively. As a result of the subsequent photocatalytic treatment, both airborne residues were eliminated within a contact time with TiO2 as short as 12 s. The results contribute to the possible application of the studied approach in closed-loop energy-saving ventilation systems.