Optimization Research on Dye Degradation Using Persulfate/Ferrous Ion/UV Process: Application for Methylene Blue and Textile Wastewater Treatment

The rapid development of the textile industry has led to an increasing discharge of dye effluents into the environment, posing a major environmental issue due to the recalcitrance and harmfulness of colorants. This work investigated the degradation of Methylene Blue (MB) through the persulfate‐based process and evaluated its applicability for treating actual textile wastewater. The influences of pH, [Fe 2+ ], and [S 2 O 8 2− ] on MB removal were examined, and the process was further optimized using the Box–Behnken design (BBD) to systematically evaluate their interactive effects. The result revealed that the optimum condition for photocatalytic persulfate reaction for MB removal was at pH 3.07; Fe 2+ concentration of 19.5 mM, and S 2 O 8 2− concentration of 31.3 mM, the removal rate of MB was achieved at 95.33% after 60 min reaction. Under optimal conditions, the persulfate‐based advanced oxidation process (AOP) demonstrated good performance in treating real textile effluent, attaining 83.97% COD removal and 90.00% color removal, thereby reaching Vietnam's national discharge standard for the effluent of the textile industry (QCVN 13‐MT:2015/BTNMT, Column B). This study provides a novel and practical contribution by integrating single‐factor evaluation with RSM optimization to identify key operational parameters governing persulfate activation and dye degradation.