Study of the performance of stainless steel and tungsten as plasma electrodes in the degradation of remazol red waste using the anodic plasma electrolysis method

Remazol Red (RR) is a persistent dye used extensively in textile industries, posing significant environmental challenges due to its resistance to conventional treatment methods. The anodic plasma electrolysis process, an advanced oxidation process (AOP), is one of the promising technologies for degrading RR that generates increased radical hydroxyl (OH•). This study aims to compare stainless steel and tungsten in terms of RR degradation and erosion rate. In addition, it also assesses the effect of power and air injection rates on RR degradation. The results show that stainless steel achieved an RR degradation of 94.73% in just 8 min, whereas tungsten only managed 84.54%. In terms of erosion, stainless steel experienced a minimal erosion of electrode, only 0.07 g, whereas tungsten exhibited a higher erosion, reaching 1.8 g within a 30-min timeframe. Based on this research, the recommended operating conditions are 1.2 L.min^-1 air injection rate and 500 W power level. Under these conditions, RR degradation reached 99.84%, Pt-Co degradation was 99.16%, and COD reduction reached 84.16% from the initial 200 ppm waste concentration with an additional 20 ppm FeSO₄. The by-products obtained were 0.438 mmol of ammonia (NH₃) and 1.736 mmol of nitrate (NO_3–).