Enhanced removal of malachite green from wastewater using nonthermal plasma gliding arc discharge combined with ferrate oxidation

The rapid and complete removal of Malachite Green (MG) dye was effectively achieved by combining potassium ferrate (Fe(VI)) treatment with nonthermal plasma discharge in both deionized water (DIW) and tap water (TW). This study evaluated the decolorization and mineralization efficiencies under varying MG concentrations, Fe(VI) dosages, and pH levels, as well as the impact of radical scavengers on the process. Fe(VI) alone resulted in moderate decolorization (35.01 %) and low mineralization (21.46 %) at an MG concentration of 50 mg/L in DIW. Plasma discharge alone achieved mineralization rates of 20.6 % in TW and 24.16 % in DIW. While complete decolorization was observed for all initial MG concentrations, it required significantly longer treatment times (>30 min). However, the combination of Fe(VI) with plasma (Fe(VI)-Plasma) demonstrated significant synergistic effects, achieving total decolorization and high mineralization rates -up to 92.5 % in DIW and 88.7 % in TW for 20 mg/L MG- at much shorter treatment times. Radical scavenger tests revealed that hydroxyl radicals (OH) were the primary oxidants in MG degradation, followed by superoxide radicals and electrons. These findings suggest that the combined Fe(VI)-Plasma technology is a promising and efficient solution for dye removal, reducing both chemical usage and treatment time.