title: Photodegradation of selected β-blockers in aqueous fulvic acid solutions: kinetics, mechanism, and product analysis.
abstract: 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.
authors.affiliation: School of Environmental Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074, China. ychen@mail.hust.edu.cn
authors.forename: Yong
authors.initials: Y
authors.lastname: Chen
authors.forename: Hong
authors.initials: H
authors.lastname: Li
authors.forename: Zongping
authors.initials: Z
authors.lastname: Wang
authors.forename: Huijie
authors.initials: H
authors.lastname: Li
authors.forename: Tao
authors.initials: T
authors.lastname: Tao
authors.forename: Yuegang
authors.initials: Y
authors.lastname: Zuo
mesh_terms: D000319:Adrenergic beta-Antagonists / Q000737:chemistry*; D001578:Benzopyrans / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008280:Magnetics; D008670:Metals / Q000737:chemistry; D055668:Photochemical Processes; D013056:Spectrophotometry, Ultraviolet; D014867:Water / Q000737:chemistry
chemical_list: D000319:Adrenergic beta-Antagonists; D001578:Benzopyrans; D008670:Metals; D014867:Water; C005023:fulvic acid