Enhancement of phenol degradation in aqueous solution by a hollow screw like electrode in gas-liquid DBD

Nonthermal plasma process of dielectric barrier discharge was successfully applied to experimental phenol degradation in a synthetic waste water aqueous solution. A typical coaxial reactor was disposed vertically but the surface of the high voltage internal electrode was shaped like a hollow screw. This electrode allowed to have a quasi-homogeneous plasma in all the length of the reactor and the inter-electrode space. With this configuration was possible to decrease the typical consumed electric power by the reactor and the liquid temperature at the end of the experience. A 90%Ar-10%O2, 80%Ar-20%O2 or 100%O2 gas mixture flowed across the gas gap and on the liquid surface. The applied electric power was in the range of 18-23 kV at 1.5 kHz. A 100%O2 gas mixture, experimental results showed an enhancement of removal efficiency beyond of 99% compared with a smooth surface cylindrical electrode after 1 hour of treatment. Also, this high efficiency was obtained with lower released power compared with that of smooth surface cylindrical electrode.