Reactive Black 5 elimination via Cu(II)-induced sodium percarbonate process: Box-Behnken design, mechanism profiling, application performance, and energy boosting

The utilization of sodium percarbonate (SPC, Na₂CO₃·1.5H₂O₂) as an alternative to H₂O₂ for degrading recalcitrant organics in advanced oxidation is emerging due to SPC’s stability, safety, and pH adaptability. This study innovatively employed Cu(II)-activated SPC to remove reactive black 5 (RB5), focusing on Box-Behnken design (BBD), mechanism profiling, application performance, and energy boosting. BBD and response surface methodology optimized conditions (2.592 mM Cu(II), 0.022 mM SPC, pH 7.18) achieved 90.08% RB5 removal (R² = 0.9997, prediction error < 1%), with the model showing strong predictive capability. Quenching experiments and liquid chromatography-mass spectrometry (LC-MS) revealed that 1O2, O2•−, and CO3•− were the main active species in oxidizing RB5 through three possible pathways. Cl⁻, SO₄²⁻, NO₃⁻, and HCO₃⁻ (0.1-5.0 mM) contained in the ultrapure water did not inhibit RB5 removal in the Cu(II)/SPC system, and the Cu(II)/SPC could remove 76.1% of RB5 in industrial wastewater, demonstrating the potential for practical application of this system. The application of energy (heating, ultraviolet light, ultrasound) significantly improved the effectiveness of the Cu(II)/SPC system in degrading RB5; thus, these means can be used to assist in the activation of SPC in real dye wastewater treatment. This work provides theoretical and practical insights for SPC-based advanced oxidation processes.