Mineralization of Rhodamine B dye in water using dielectric barrier plasma jet with process optimization

• Dielectric barrier discharge jet destroys and mineralizes Rhodamine B dye in water. • Removal efficiency was achieved at 96% with energy efficiency of 0.193 g/kWh. • Optimal operation is 60 W power, 20 kHz frequency, and argon flow rate of 1.5 L/min. • The Rhodamine B removal follows pseudo-first-order kinetics with k = −0.18 min -1 . • Degradation includes de-ethylation, chromophore cleavage, and mineralization steps. To address the persistent challenge of textile wastewater treatment, a non-thermal dielectric barrier discharge (DBD) plasma jet process was developed and optimized for the effective removal and mineralization of Rhodamine B dye from synthetic wastewater. Using the Box–Behnken design and response surface methodology, the influence of three key process parameters- applied power (30–60 W), power frequency (10–20 kHz), and argon gas flow rate (0.5–1.5 L/min)- and their interactions on the decomposition of RhB were systematically evaluated and optimized for an initial RhB concentration of 100 mg/L. Under optimal conditions of 60 W applied power, 20 kHz frequency, and 1.5 L/min gas flow rate, the DBD plasma jet achieved a high RhB removal efficiency of 96% within 20 min, with an energy efficiency of 0.193 g/kWh and a G 50 energy yield of 0.266 g/kWh. The process followed pseudo-first-order kinetics, with mineralization of the dye evidenced by a 94% reduction in chemical oxygen demand, 92% reduction in total organic carbon, and the formation of nitrate and ammonium ions. The degradation pathway of RhB, involving de-ethylation, chromophore cleavage, and subsequent mineralization, was proposed based on optical emission spectroscopy and liquid chromatography-mass spectrometry analyses. This study demonstrates the potential of the DBD plasma jet as an efficient and sustainable method for the treatment of dye-laden wastewater.