Application of Box-Behnken design with response surface methodology for modeling and optimizing ultrasonic oxidation of arsenite with H ₂O₂

A combined ultrasound (US)/H₂O₂ process was used to oxidize arsenite to arsenate, yielding a synergistic effect value of 1.26. This showed that the combined process could be an effective method of oxidizing arsenite, instead of using either ultrasonic or H₂O₂ oxidation processes. This combined process was successfully modeled and optimized using a Box-Behnken design with response surface methodology (RSM). The effects of the US power density, the initial concentration of arsenite, and the H₂O₂ concentration on the sonochemical oxidation efficiency of arsenite were investigated. Analysis of variance indicated that the proposed quadratic model successfully interpreted the experimental data with coefficients of determination of R ² = 0.95 and adjusted R ² = 0.91. Through this model, we can predict and control the oxidation efficiency under different conditions. Furthermore, the optimal conditions for the oxidation of arsenite were found to be a US power density of 233.26 W L^-1, an initial arsenite concentration of 0.5 mg L ^-1, and an H₂O₂ concentration of 74.29 mg L^-1. The predicted oxidation efficiency obtained from the RSM under the optimal conditions was 88.95%. A confirmation test of the optimal conditions verified the validity of the model, yielding an oxidation efficiency of 90.1%. [Figure not available: see fulltext.]