title: Degradation kinetics and pathways of three calcium channel blockers under UV irradiation.
abstract: Calcium channel blockers (CCBs) are a group of pharmaceuticals widely prescribed to lower blood pressure and treat heart diseases. They have been frequently detected in wastewater treatment plant (WWTP) effluents and downstream river waters, thus inducing a potential risk to aquatic ecosystems. However, little is known about the behavior and fate of CCBs under UV irradiation, which has been adopted as a primary disinfection method for WWTP effluents. This study investigated the degradation kinetics and pathways of three commonly-used CCBs, including amlodipine (AML), diltiazem (DIL), and verapamil (VER), under UV (254 nm) irradiation. The chemical structures of transformation byproducts (TBPs) were first identified to assess the potential ecological hazards. On that basis, a generic solid-phase extraction method, which simultaneously used four different cartridges, was adopted to extract and enrich the TBPs. Thereafter, the photo-degradation of target CCBs was performed under UV fluences typical for WWTP effluent disinfection. The degradation of all three CCBs conformed to the pseudo-first-order kinetics, with rate constants of 0.031, 0.044 and 0.011 min(-1) for AML, DIL and VER, respectively. By comparing the MS(2) fragments and the evolution (i.e., formation or decay) trends of identified TBPs, the degradation pathways were proposed. In the WWTP effluent, although the target CCBs could be degraded, several TBPs still contained the functional pharmacophores and reached peak concentrations under UV fluences of 40-100 mJ cm(-2).
authors.affiliation: Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, 18 Shuang-qing Road, Beijing 100085, China.
authors.forename: Bing
authors.initials: B
authors.lastname: Zhu
authors.affiliation: Water and Soil Quality Research Group, Department of Environmental Chemistry, IDAEA-CSIC, 18-26 c/Jordi Girona, 08034 Barcelona, Spain.
authors.forename: Bozo
authors.initials: B
authors.lastname: Zonja
authors.affiliation: Department of Chemical Engineering, University of Barcelona, Marti i Franques 1, 08028 Barcelona, Spain.
authors.forename: Oscar
authors.initials: O
authors.lastname: Gonzalez
authors.affiliation: Department of Chemical Engineering, University of Barcelona, Marti i Franques 1, 08028 Barcelona, Spain. Electronic address: carmesans@ub.edu.
authors.forename: Carme
authors.initials: C
authors.lastname: Sans
authors.affiliation: Water and Soil Quality Research Group, Department of Environmental Chemistry, IDAEA-CSIC, 18-26 c/Jordi Girona, 08034 Barcelona, Spain.
authors.forename: Sandra
authors.initials: S
authors.lastname: Pérez
authors.affiliation: Water and Soil Quality Research Group, Department of Environmental Chemistry, IDAEA-CSIC, 18-26 c/Jordi Girona, 08034 Barcelona, Spain; Catalan Institute of Water Research, c/Emili Grahit, 101 Edifici H2O, Parc Cientific i Tecnologic de la Universitat de Girona, E-17003 Girona, Spain.
authors.forename: Damia
authors.initials: D
authors.lastname: Barceló
authors.affiliation: Department of Chemical Engineering, University of Barcelona, Marti i Franques 1, 08028 Barcelona, Spain.
authors.forename: Santiago
authors.initials: S
authors.lastname: Esplugas
authors.affiliation: Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, 18 Shuang-qing Road, Beijing 100085, China.
authors.forename: Ke
authors.initials: K
authors.lastname: Xu
authors.affiliation: Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, 18 Shuang-qing Road, Beijing 100085, China. Electronic address: qiangz@rcees.ac.cn.
authors.forename: Zhimin
authors.initials: Z
authors.lastname: Qiang
mesh_terms: D017311:Amlodipine / Q000737:chemistry / Q000528:radiation effects; D002121:Calcium Channel Blockers / Q000737:chemistry* / Q000528:radiation effects*; D004110:Diltiazem / Q000737:chemistry / Q000528:radiation effects; D004203:Disinfection / Q000379:methods; D007700:Kinetics; D010782:Photolysis; D014466:Ultraviolet Rays; D014700:Verapamil / Q000737:chemistry / Q000528:radiation effects; D062065:Wastewater / Q000737:chemistry; D014874:Water Pollutants, Chemical / Q000737:chemistry*
chemical_list: D017311:Amlodipine; D002121:Calcium Channel Blockers; D004110:Diltiazem; D014700:Verapamil; D062065:Wastewater; D014874:Water Pollutants, Chemical
keywords: Calcium channel blockers; Photolysis kinetics; Transformation byproducts; UV irradiation; Wastewater treatment plant effluent