Trimethoprim (TMP) is a pharmaceutical compound, which is commonly found in the water environment. The UV/chlorine process forms several reactive species, including hydroxyl radicals (HO•) and reactive chlorine species, to degrade contaminants. The influencing factors and the optimal operational conditions for the degradation of TMP by the UV/chlorine process were investigated. The degradation of TMP was much faster by the UV/chlorine process as compared to the UV alone or free chlorine alone process. A kinetic model was developed to simulate the degradation of TMP and determine the unknown rate constants. This study also predicted the relative contributions of each of the reactive species and photolysis using the developed kinetic model. It was found that the ClO• radical was the major reactant responsible for the degradation of TMP. Furthermore, the most important finding was the identification of the best operational conditions. The best operational conditions resulted in the lowest use of energy and electrical energy per order (EE/O), namely, (1) for the ultrapure water, the optimum intensity of the UV light and the free chlorine dosage were 2.56 Einstein/L·s and 0.064 mM, respectively, with a minimum EE/O of 0.136 kWh/m³; and (2) for the water matrix containing 3 mg/L NOM, the optimum intensity of the UV light and the free chlorine dosage were 3.45 Einstein/L s and 0.172 mM, respectively, with a minimum EE/O of 0.311 kWh/m³.

中文翻译：

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使用紫外线/游离氯工艺降解甲氧苄啶：影响因素和最佳操作条件

甲氧苄啶 (TMP) 是一种药物化合物，常见于水环境中。紫外线/氯过程会形成多种活性物质，包括羟基自由基 (H2O•) 和活性氯物质，以降解污染物。研究了紫外/氯法降解TMP的影响因素和最佳操作条件。与单独的 UV 或单独的游离氯过程相比，UV/氯过程对 TMP 的降解要快得多。开发了一个动力学模型来模拟 TMP 的降解并确定未知的速率常数。该研究还使用开发的动力学模型预测了每种活性物质和光解的相对贡献。发现 ClO• 自由基是导致 TMP 降解的主要反应物。此外，最重要的发现是确定了最佳操作条件。最佳操作条件导致最低的能源和电能使用量（EE/O），即（1）对于超纯水，最佳紫外线强度和游离氯剂量为 2.56 Einstein/L·分别为 s 和 0.064 mM，最低 EE/O 为 0.136 kWh/m³ ; (2) 对于含有 3 mg/L NOM 的水基质，紫外光的最佳强度和游离氯剂量分别为 3.45 Einstein/L s 和 0.172 mM，最小 EE/O 为 0.311 kWh/m ³ .