Plasma–Kinetic Coupling and Redox Mechanisms in the Degradation of Acid Red 51 by Atmospheric Corona Discharge

This study investigates the degradation of the xanthene dye Acid Red 51 (ARE‐51) using atmospheric‐pressure corona discharge plasma, integrating electrical characterization, optical emission spectroscopy (OES), kinetic modeling, and physicochemical analysis to establish a unified plasma–liquid interaction framework. A degradation efficiency of ~82% was achieved within 90 min, with apparent pseudofirst‐order kinetics ( k ≈0.017 min −1 ). However, the observed kinetics are governed by a quasisteady‐state flux of reactive species rather than intrinsic reaction rates. OES analysis confirms the generation of key reactive oxygen and nitrogen species (RONS), including •OH, O 3 , and H 2 O 2 , whose formation is directly linked to electron temperature (~12 eV) and discharge characteristics. A two‐stage degradation mechanism is identified: an initial reduction‐dominated phase associated with chromophore cleavage, followed by an oxidation‐dominated phase driven by RONS leading to fragmentation and mineralization. Physicochemical parameters (pH, EC, ORP, and TDS) reveal strong redox transitions and ionic product formation, supporting the proposed mechanism. Energy yield (G 50 ≈0.3–0.6 g·kWh −1 ) demonstrates competitive performance without chemical additives. This work provides a quantitative link between plasma properties and degradation kinetics, offering a new paradigm for the design and optimization of plasma‐based advanced oxidation processes.