Degradation of Synthetic Dyeing Wastewater by Underwater Electrical Discharge Processes

Abstract

Electrical discharge treatments of synthetic dyeing wastewater were carried out with two different systems: underwater pulsed electrical discharge (UPED) and underwater dielectric barrier discharge (UDBD). Reactive Blue 4 (RB4) and Acid Red 4 (AR4) were used as model contaminants for the synthetic wastewater. The performance of the aforementioned systems was compared with respect to the chromaticity removal and the energy requirement. The results showed that the present electrical discharge systems were very effective for degradation of the dyes. The dependences of the dye degradation rate on treatment time, initial dye concentration, electrical energy, and the type of working gas including air, O2, and N2 were examined. The change in the initial dye concentration did not largely affect the degradation of either RB4 or AR4. The energy delivered to the UPED system was only partially utilized for generating reactive species capable of degrading the dyes, leading to higher energy requirement than the UDBD system. Among the working gases, the best performance was observed with O2. As the degradation proceeded, the concentration of total dissolved solids and the solution conductivity kept increasing while pH showed a decreasing trend, revealing that the dyes were effectively mineralized.

Catalytic/inhibitory effect of the joint presence of two dyes on its destruction by underwater plasma processes: a tool for optimization parameters of treatment

“…A large number of works are devoted to studying the effect of electric discharges on azo dyes due to the widespread use of this class of dyes [14, 15, 17, 19, 25-27, 30, 32, 34]. It should be noted that the growth of studies on the decomposition of anthraquinone dyes because of carcinogenic properties in water [20,23,24,29,31,33,35]. However, the wastewater of industrial factories contains more than one dye.…”

Electrical and spectral characteristics of a tube-to-plate helium plasma generated using dielectric barrier discharge in water

“…Currently, the electrical discharge of DBD in water used to remove organic contaminants could be divided into two main groups, namely electrical discharge inside the reactor immersed in water and direct electrical discharge in water. The plasmas need to transfer a section of distance before reacting with organic pollutants for the electrical discharge inside the reactors which are immersed in water [9][10][11][12], leading to disappear of short lifetime active species before chemical reactions. It could seriously affect the degradation efficiency of organic pollutants in water, because the short lifetime active species such as OH* and O* play an important role for organic pollutants removal.…”

Decolorization of methyl violet in simulated wastewater by dielectric barrier discharge plasma

“…Nonequilibrium plasma is considered to be a highly efficient and environmentally friendly method to solve this problem because it is a rich source of high-energy, active particles. [7][8][9][10] Regarding the present research situation, although nonequilibrium plasma technology has been applied in wastewater processing research, [10][11][12][13][14][15][16] the technology is not yet mature due to problems such as high cost and its unknown mechanism of action. In particular, for practical application in industry, the processing speed and decolorization efficiency need to be further improved, and the energy consumption should be reduced to as low as possible.…”