Influence of Relative Humidity on Non-Thermal Surface Discharge Plasma Processing of Gas-Phase Toluene

The performance of gas-phase toluene decomposition was studied by using a surface discharge plasma reactor with or without photo-catalyst under different relative humidity: 0%, 25% and 50% at room temperature and atmospheric pressure .The main purpose of this work is to investigate the effect of relative humidity on the discharge character and toluene oxidation. It was found that the electrical charge and energy density decreased when the percentage of water in air increased. The performance of the plasma became better in humidified air compared with that in the dry air (RH=0%).It was observed that toluene removal rate, the selectivity to CO₂ and CO_x in the decomposition products and energy efficiency increased with the relative humidity increasing. However, it was noticed that humidity had some adverse influence on photo-catalysts activity. It was found that compared with the plasma alone system, plasma-photocatalysis system had higher removal efficiency and CO₂ selectivity in moderate and low relative humidity (RH=25%,RH=0%).But with continuing increase of relative humidity(RH=50%), the catalyst activity was suppressed and energy efficiency decreased in the plasma-photocatalysis system.