Investigating the Performance of Cold Plasma in Removing Methylene Blue Dye from Textile Wastewater

Abstract

Advanced oxidation process is an efficient and innovative method for the complete removal of organic pollutants, which works by using active species, especially hydroxyl radicals. In this process, different oxidation mechanisms are used. Direct electrical discharge on the surface and inside the liquid is a more complex and effective process than electrical discharge on gases. In this process, the electronic current is transferred by surface and water ions and produces plasma, which leads to chemical and physical effects such as the production of radicals and ultraviolet light. In this study, wastewater from textile industries was selected as the target wastewater. The removal of methylene blue as one of the important and toxic dyes in this type of wastewater was investigated under the influence of atmospheric pressure plasma. The electrodes used to generate plasma were made of 316 stainless steel. The experiment was carried out for a duration of 2.5 to 60 minutes. In the conducted analyses, optimal pH, suitable injected gas into the reactor, chemical oxygen demand, effective voltage (V), and distance between electrodes (d) were also studied. The results showed that corona pulse plasma had a high efficiency in dye removal, with over 99% color removal achieved in less than 10 minutes using injected oxygen gas into the system at a pH of 8 and an effective voltage of 130 kV. Additionally, the highest reduction in COD value in the corona pulse method for real textile wastewater reached from 1760 to 200 mg/L, and complete color removal was achieved, reducing its color from 2500 Pt/CO to 75 Pt/CO, indicating the extraordinary impact of this method.

Keywords

• advanced oxidation
• plasma
• oxidizing species
• methylene blue
• textile effluent