Theoretical study on the degradation of hydroxybenzophenones by hydroxyl radical in water: Microscopic reaction mechanism, kinetics, toxicity

This study used the DFT M062X/6-311G (d, p) method to explain the microscopic reaction mechanism of hydroxyl radical (•OH) with four benzophenones at the molecular level. The results showed that the most favorable reaction mechanism is the radical adduct formation (RAF) reaction. The order of reaction rate constants is K_{•OH, BP1} (2.18 × 10⁹ M⁻¹ s⁻¹) > K_{•OH, 2HB} (4.35 × 10⁸ M⁻¹ s⁻¹) > K_{•OH, 4DHB} (1.23 × 10⁸ M⁻¹ s⁻¹) > K_{•OH, 4HB} (7.08 × 10⁷ M⁻¹ s⁻¹). Based on this, we established a kinetic model to compare two advanced oxidation processes (AOPs). The results showed that the degradation efficiency of benzophenones by the UV/H₂O₂ process was 16.0–53.8 % higher than that of the Fenton method. The purpose of this study is to gain a deeper understanding of the basic principles of hydroxyl degradation of benzophenone derivatives, and to provide a theoretical reference for process selection in the actual sewage treatment process.