Performance of CaO2-Based Processes for the Decolorization of a Reactive Textile Dye

The adoption of environmentally friendly technologies for treating textile dye-containing wastewater through advanced oxidation processes is critical for maintaining ecological and environmental health. Calcium peroxide (CaO2) has emerged as a powerful oxidant with significant oxidizing potential. This study evaluates the performance of Direct-CaO2, UV/CaO2, Fe2+/CaO2, and UV/ Fe2+/CaO2 processes for the decolorization of RB222 in an aqueous solution. Optimal conditions were identified, with the CaO2 dosage being the most influential independent variable. At a pH of 10 and a CaO2 dosage of 1.0 g, the Direct-CaO2 and UV/CaO2 processes achieved dye removal efficiencies of 79.80% and 90.40%, respectively, with removal rates of 0.665 mg/L/min and 0.755 mg/L/min for 100 mg/L RB222. The Fe2+/CaO2 and UV/Fe2+/CaO2 processes required a pH of 2.50 and a Fe2+/CaO2 ratio of 0.40 for optimum performance. Under these conditions, Fe2+/CaO2 achieved complete RB222 removal in 40 min, corresponding to a removal rate of 2.50 mg/L/min with 0.125 g CaO2. UV/Fe2+/CaO2 achieved the same in just 10 min, with a removal rate of 10 mg/L/min using 0.0625 g CaO2.The presence of Cl- anions adversely affected the efficiency of RB222 decolorization. Thermodynamic analysis confirmed that the decolorization reactions in all processes are endothermic in nature. The findings highlight the high efficiency of CaO2-based processes for RB222 removal, offering a promising approach for the treatment of dye-contaminated wastewater.