Simultaneous degradation of phenol-Cr(VI) wastewater on air injection plasma electrolysis using titanium anode

Phenol and Cr(VI) are dangerous wastewater were degraded simultaneously by reactive chemical species on plasma electrolysis reactor where direct air injection into plasma zone which titanium as the working electrode. Air injection contributes to increasing the formation of the radical species, such as radical ·OH, ·H, O₂^·−, and H₂O₂ molecules, even reducing the energy consumption. The effects of various air injection flow rates, pH, and voltages on phenol–Cr(VI) degradation were observed. The removal efficiency on the binary system was achieved 66% for phenol and 91% for Cr(VI) within 30 min, where the optimum condition of air injection flow rate is 0.2 L min⁻¹ and pH 3.7. The energy efficiency of degradation was compared with that in other competitive processes. Increasing the voltage at constant power decreases the number of ·OH and ·H and increases the number of H₂O₂ molecules, indicating the formation of new reactive species. This study validated the synergistic effect on the simultaneous oxidation and reduction processes in wastewater.