Canonica Silvio, Meunier Laurence, von Gunten Urs
Eawag, Swiss Federal Institute of Aquatic Science and Technology, 8600 Dübendorf, Switzerland.
Water Res. 2008 Jan;42(1-2):121-8. doi: 10.1016/j.watres.2007.07.026. Epub 2007 Jul 26.
The kinetics of Ultraviolet C (UV-C)-induced direct phototransformation of four representative pharmaceuticals, i.e., 17alpha-ethinylestradiol (EE2), diclofenac, sulfamethoxazole, and iopromide, was investigated in dilute solutions of pure water buffered at various pH values using a low-pressure and a medium-pressure mercury arc lamp. Except for iopromide, pH-dependent rate constants were observed, which could be related to acid-base equilibria. Quantum yields for direct phototransformation were found to be largely wavelength-independent, except for EE2. This compound, which also had a rather inefficient direct phototransformation, mainly underwent indirect phototransformation in natural water samples, while the UV-induced depletion of the other pharmaceuticals appeared to be unaffected by the presence of natural water components. At the UV-C (254 nm) drinking-water disinfection fluence (dose) of 400 Jm(-2), the degree of depletion of the select pharmaceuticals at pH=7.0 in pure water was 0.4% for EE2, 27% for diclofenac, 15% for sulfamethoxazole, and 15% for iopromide, indicating that phototransformation should be seriously taken into account when evaluating the possibility of formation of UV transformation products from pharmaceuticals present as micropollutants.
使用低压和中压汞弧灯，在不同pH值缓冲的纯水稀溶液中研究了紫外线C（UV-C）诱导的四种代表性药物，即17α-乙炔雌二醇（EE2）、双氯芬酸、磺胺甲恶唑和碘普罗胺的直接光转化动力学。除碘普罗胺外，观察到了与pH相关的速率常数，这可能与酸碱平衡有关。发现除EE2外，直接光转化的量子产率在很大程度上与波长无关。这种化合物的直接光转化效率也相当低，在天然水样中主要发生间接光转化，而紫外线诱导的其他药物的消耗似乎不受天然水成分存在的影响。在UV-C（254 nm）饮用水消毒通量（剂量）为400 Jm(-2)时，在pH = 7.0的纯水中，所选药物的消耗程度对于EE2为0.4%，双氯芬酸为27%，磺胺甲恶唑为15%，碘普罗胺为15%，这表明在评估作为微污染物存在的药物形成紫外线转化产物的可能性时，应认真考虑光转化。
