Decomposition of Phenol in Water by a Cylindrical Wetted-Wall Reactor Using Direct Contact of Gas Corona Discharge

Abstract

A water purification reactor using direct contact of gas corona discharge with water is developed into a cylindrical-anode wetted-wall reactor. In a modification from the previous plate anode to the present cylindrical anode, it is expected that reactive radicals produced in a plasma region around a wire cathode in a gas phase can efficiently reach the surface of a flowing-water film so that reactive species such as an OH radical can be effectively produced in water. In this study, aqueous phenol was decomposed using the modified reactor to evaluate its efficiency. As a result, the electron efficiency and energetic efficiency of the cylindrical-anode wetted-wall reactor were respectively 2-3 and 3-4 times greater than those of the plate-anode reactors. Furthermore, the activity of the radical-producing plasma in the proposed reactor was 2 orders of magnitude higher than that of the plate-anode reactor. The experiments applying varied water flow rates and discharge currents indicated that the condition that keeps a smooth water surface is important to achieve maximum decomposition efficiency. In addition, it is found that there is an optimized anode radius to attain high decomposition efficiency.

Characterization of plasma-induced phenol advanced oxidation process in a DBD reactor

“…There is currently much ongoing research to exploit and apply electrical discharges for water purification [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16]. Many different prototype reactors have been developed, including systems in which the discharge occurs into [2][3][4][5] or above the liquid [6][7][8][9], as well as hybrid reactors, which utilize both gas phase non-thermal plasma and direct liquid phase corona-like discharge in the water [10,11].…”

“…Many different prototype reactors have been developed, including systems in which the discharge occurs into [2][3][4][5] or above the liquid [6][7][8][9], as well as hybrid reactors, which utilize both gas phase non-thermal plasma and direct liquid phase corona-like discharge in the water [10,11]. In addition reactors have been reported in which the solution to be treated is supplied into the discharge area as an aerosol [12] or as a falling-water film [13,14].…”

The Role of Pulse Voltage Amplitude on Chemical Processes Induced by Streamer Discharge at Water Surface

“…As radical generation primarily depends on plasma contact area, electron energy diffused from the H.V. electrode tip relates to excitation and dissociation of water molecules [13,14]. In our experiments, the gap distance between the H.V.…”

“…Discharge propagation at water surface was captured using a high-speed video camera (VW-6000, Keyence, Japan) and an ultra-high-speed framing camera with 5 ns exposure and 5 ns inter-frame time (Ultraneo, Nac, Japan). OH˙ radicals, O3, and other species have a very short-lifetime (a few nano-seconds to micro-seconds) [14]. The paper also presents degradation of indigo carmine organic dye results, as a model pollutant to evaluate effects of pulse voltage on the chemical processes following the water surface discharge.…”

“…H 2 O 2 is a basic indicator of OH • radicals, and is formed primarily by recombination of OH • radicals in the discharge region [13]. It has a relatively long lifetime, while OH • radicals, O 3 , and other species have a very short-lifetime (a few nano-seconds to micro-seconds) [14]. The paper also presents degradation of indigo carmine organic dye results, as a model pollutant to evaluate effects of pulse voltage on the chemical processes following the water surface discharge.…”