Photodegradation characteristics of pharmaceuticals and personal care products (PPCPs) during UV irradiation are of practical and scientific importance in selecting operational parameters during water treatment processes. In this study, the molar extinction coefficient (ε), quantum yield (φ), and degradation kinetics of neutral/anionic forms of sulfamethoxazole (SMX) and ibuprofen (IBU) were compared by varying solution pH. The degradation kinetics of the target compounds were observed to reversely correlate to the energy gap between highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) values of the target compounds. Then, a kinetic model for predicting the direct photolytic rates at different solution pH was established based on ε and φ of neutral/anionic species. The root mean squared errors for the modeled values suggest that the model exhibits good predictive power. Finally, in order to evaluate the electrical energy consumption during the UV direct photolysis process, the electrical energy per order (EE/O) was assessed. The experimental and modelling results are important to elucidate the mechanism of degradation of target PPCPs under UV irradiation and allow for the selection of optimal conditions in water treatment processes.

中文翻译：

---

磺胺甲恶唑和布洛芬的紫外线直接光解：实验和模型研究

紫外线照射过程中药物和个人护理产品（PPCP）的光降解特性对于选择水处理过程中的操作参数具有实际和科学的重要性。在这项研究中，通过改变溶液pH值，比较了磺胺甲恶唑（SMX）和布洛芬（IBU）的摩尔消光系数（ε），量子产率（φ）和降解动力学。观察到目标化合物的降解动力学与目标化合物的最高占据分子轨道（HOMO）和最低未占据分子轨道（LUMO）值之间的能隙反向相关。然后，基于ε建立了预测不同溶液pH下直接光解速率的动力学模型。和φ是中性/阴离子种类。建模值的均方根误差表明该模型具有良好的预测能力。最后，为了评估UV直接光解过程中的电能消耗，对每订单的电能（EE / O）进行了评估。实验和建模结果对于阐明目标PPCP在紫外线照射下的降解机理以及在水处理过程中选择最佳条件非常重要。