Ferric ion-ascorbic acid complex catalyzed calcium peroxide for organic wastewater treatment: Optimized by response surface method

Hydrogen peroxide (H₂O₂) disproportionation, iron precipitation, and narrow pH range are the drawbacks of traditional Fenton process. To surmount these barriers, we proposed a ferric ion (Fe³⁺)-ascorbic acid (AA) complex catalyzed calcium peroxide (CaO₂) Fenton-like system to remove organic dyes in water. This collaborative Fe³⁺/AA/CaO₂ system presented an obvious improvement in the methyl orange (MO) decolorization, and also effectively eliminated other dyes. Response surface method was employed to optimize the running parameters for this coupling process. Under the optimized arguments (2.76 mmol/L Fe³⁺, 0.68 mmol/L AA, and 4 mmol/L CaO₂), the MO removal achieved 98.90% after 15 min at pH 6.50, which was close to the computed outcome of 99.30%. Furthermore, this Fenton-like system could perform well in a wide range of pH (3–11), and enhance the H₂O₂ decomposition and Fe ions recycle. The scavenger experiment result indicated that hydroxyl radical, superoxide anion free radical, and singlet oxygen were acted on the dye elimination. Moreover, electron spin resonance analysis corroborated that the existences of these active species in the Fe³⁺/AA/CaO₂ system. This study could advance the development of Fenton-like technique in organic effluent disposal.