School of Environmental Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074, China.
Water Res. 2012 Jun 1;46(9):2965-72. doi: 10.1016/j.watres.2012.03.025. Epub 2012 Mar 20.
The photodegradation of the widely used β-blockers atenolol and metoprolol were investigated in the presence of fulvic acid (FA) under simulated sunlight. Both atenolol and metoprolol undergo indirect photodegradation in the FA solutions. The triplet excited state of FA ((3)FA(∗)) was verified to be main reactive species responsible for the photosensitized degradation of β-blockers. An electron transfer mechanism for the interaction between β-blockers and (3)FA(∗) was proposed on the basis of a series of experiments. Magnetic property of metal ions exhibited significant impact on photosensitized degradation. Diamagnetic metal ions such as Mg(2+), Ca(2+), Zn(2+), and Al(3+) negligibly affected the degradation. In contrast, paramagnetic metal ions including Mn(2+), Cu(2+), Fe(3+), and Cr(3+) markedly inhibited the reactions in the order of Cr(3+) < Fe(3+) < Cu(2+) < Mn(2+). The inhibition was related to the complexation ability with FA. By LC-ESI-MS/MS analysis, deisopropyl-atenolol (metoprolol) was identified as the main photosensitized product. The degradation pathways of β-blockers involving electron transfer processes were proposed. This finding strongly suggests that (3)FA(∗) was important reactive species for the degradation of β-blockers in natural waters.
在模拟太阳光下，研究了广泛使用的β受体阻滞剂阿替洛尔和美托洛尔在富里酸（FA）存在下的光降解情况。阿替洛尔和美托洛尔在 FA 溶液中均经历间接光降解。证实 FA 的三重激发态（(3)FA(∗)）是导致β受体阻滞剂光敏降解的主要反应性物质。基于一系列实验，提出了β受体阻滞剂与（3）FA(∗)之间相互作用的电子转移机制。金属离子的磁性对光敏降解有显著影响。像 Mg(2+)、Ca(2+)、Zn(2+)和 Al(3+)这样的抗磁性金属离子对降解的影响可以忽略不计。相比之下，包括 Mn(2+)、Cu(2+)、Fe(3+)和 Cr(3+)在内的顺磁性金属离子则以 Cr(3+)<Fe(3+)<Cu(2+)<Mn(2+)的顺序显著抑制反应。这种抑制与与 FA 的络合能力有关。通过 LC-ESI-MS/MS 分析，确定去异丙基-阿替洛尔（美托洛尔）为主要光敏产物。提出了涉及电子转移过程的β受体阻滞剂降解途径。这一发现强烈表明，(3)FA(∗)是天然水中β受体阻滞剂降解的重要反应性物质。
