Non-thermal plasma degradation of dye using an underwater dielectric barrier discharge created inside a porous hydrophobic ceramic tube

An alternating-current-driven, atmospheric-pressure, non-thermal plasma reactor was applied to the degradation of dye in water. The plasma reactor, made of a porous hollow ceramic tube, was placed underwater and was able to disperse plasmatic gas containing various reactive species into aqueous dye solution as small bubbles through the micropores of the tube. The hydrophobic coating on the surface of the ceramic tube effectively prevented the water from permeating through it. This wastewater treatment system was able immediately to transfer plasmatic gas to aqueous solution across the porous ceramic tube and provide a large gas-liquid interfacial area, allowing efficient dye treatment. So as to simulate real dyeing wastewater, an aqueous solution comprising two different azo dyes was used. The effect of discharge power, treatment time, and flow rate of oxygen used for the creation of plasma was examined. The results suggest that this system may be useful for the treatment of organic wastewater.