Comparison of liquid and liquid‐gas phase plasma reactors for discoloration of azo dyes: Analysis of degradation products

Abstract

Three plasma systems are used for decomposition of two organic textile dyes. The highest discoloration efficiency over 90% is reached in the water falling film DBD when maximal energy of 270 and 450 kJ L−1 is applied into Reactive Yellow 125 and Direct Red 79 dye solutions, respectively. Decomposition of the dye molecules is confirmed by concentration decreases in dye chromatograms. Similar degradation products are identified in the positive diaphragm discharge and water falling film DBD. In the negative diaphragm discharge, different products are formed due to electrochemical reactions on the anode. Substitution of halogens, hydrogen addition on the azo group and the cleavage of the azo group itself are the main mechanisms contributing to the destruction of the dye molecule in the compared plasma systems.

Influence of solution properties and gas addition on hydrogen peroxide production by a novel plasma source

“…A very high electric field value is usually necessary for the initiation of the breakdown. Typical electrode configurations are point to plane [3][4][5], coaxial [6] or pin-hole systems [7][8][9][10]. Especially pin-hole systems are often combined with the additional gas bubbling that extends chemical mechanisms utilised in further applications [11][12][13].…”

Influence of Plasma-Activated Water on Physical and Physical–Chemical Soil Properties

“…Special attention is given to plasma interactions in and with liquids [3,4]. Common applications of plasma in this field are focused mainly on waste water treatment [5][6][7][8], hydrocarbons re-forming [9], the production and treatment of nanoparticles [10][11][12], surface treatment of solid materials [13,14] and, recently, also the utilization of so called plasma-activated water (PAW) for bio applications in medicine [15][16][17][18] and agriculture [19].…”

Special issue: Plasma and Liquids

“…The two different configurations of gas‐liquid plasma reactors allow for compact operation and characterization of the chemical and physical processes inside the reactor. Other papers in this issue include analysis of direct underwater discharges (Yang et al and Kozakova et al), study of pollutant treatment (Magureanu et al, Kozakova et al, Tampieri et al), determination of the fundamental species formation for plasma formed in contacting with a liquid water stream (X. Zhang et al, Tarabova et al, and Wandell et al), and analysis of plasma with organic liquids (Rezaei et al and Franclemont et al) . Of particular importance for chemical oxidation is the determination of hydroxyl radical, ·OH, concentrations and production using chemical probes (M. Zhang et al and X. Zhang et al), and in the case of an air plasma contacting the liquid the determination of nitrogen containing species and their interactions with species such as hydrogen peroxide (Tarabova et al) is necessary.…”

“…Three contributions to this Special Issue are devoted specifically to the decontamination of various compounds found in the liquid phase (Kozakova et al, Magureanu et al, Tampieri et al) and this work builds upon the environmental applications of gas‐liquid plasma that have recently been reviewed …”

“…Kozakova et al report on azo dye decoloration and degradation in liquid and liquid‐gas plasma reactors . Many studies have been reported in the literature that utilize dye decoloration (see reviews) as a means to assess the relative performance of different plasma reactors for decomposing compounds that exist primarily in the liquid phase.…”