Aqueous solutions polluted by contaminants different from those generally studied (phenol and chlorophenols) were treated in a falling film gas-liquid dielectric barrier discharge reactor. The lower was the Henry's law constant of a molecule, the better was its removal percentage, regardless of its other chemical properties. In the case of saturated molecules, the removal mechanism is the transfer of pollutants from the liquid phase to the gas phase where they react with the active species of the discharge. For phenol, the reaction with ozone in the liquid phase was estimated to be responsible of about 30% of the removal. A computational fluid dynamic modelling provided a better understanding of the phenomena, indicating that mass transfer of pollutants from liquid to gas is accelerated due to (1) the intense mixing in the liquid film and (2) the reaction of the pollutant with the active species in the gaseous phase.

International audienceA hybrid plasma-catalytic system was used in for the hydrogenation of carbon dioxide (CO2) into methane (methanation) at atmospheric pressure and very low temperature using a dielectric barrier discharge (DBD) plasma reactor packed with Ni-CexZr1−xO2 catalysts. Three catalysts were prepared by a conventional wet impregnation method, using 15 wt% of Ni loading over ceria-zirconia mixed oxides having different Ce/Zr ratios. The physico–chemical features of both catalysts and supports were evaluated by means of X-Ray Diffraction (XRD), Temperature-Programmed Reduction of H2 (H2-TPR), Temperature Programmed-Desorption of CO2 (CO2-TPD) and Transmission Electron Microscopy (TEM). The methanation experiments in the absence or in the presence of plasma were carried out in the temperature range of 90–420 °C. The hybrid plasma 15NiCZ5842 catalyst combination was found to efficiently convert CO2 into methane even at low temperature. Indeed, CO2 conversions as high as 80%, together with 100% selectivity toward methane was measured in the presence of plasma at 90 °C. On the contrary in the absence of plasma, the same conversion and selectivity were only achieved at much higher temperatures around 300 °C, for the same catalyst