title: Photodegradation of propranolol by Fe(III)-citrate complexes: kinetics, mechanism and effect of environmental media.
abstract: Photogeneration of HO was optimized in Fe(III)-citrate solution within the pH range of 3.0-9.0 to investigate its photoreactivity at neutral pH without the addition of H(2)O(2) under simulated sunlight. The generation of HO decreased with increasing pH within the range of 6.0-9.0 at the Fe(III)-to-citrate ratio of 10:50 (10(-6)M). However, when the concentration of citrate increased to 1.5 × 10(-4)M, the formation rate of HO increased in the order of pH 9.0<3.0<7.0<4.0<5.0. The pH-dependent HO production was governed by the stability of Fe(II)/Fe(II)-citrate and the amount of O(2)(-) in the solution. Propranolol can be efficiently photodegraded in Fe(III)-citrate system at pH 7.0 with pseudo-first-order constant 3.1 × 10(-4)s(-1). HO was verified to be the main reactive oxygen species (ROS) responsible for the photodegradation of propranolol. The presence of metal ions inhibited the Fe(III)-cit-induced photodegradation in the order of Mn(2+)>Cu(2+)>Ca(2+)>Mg(2+). Both humic acid (HA) and fulvic acid (FA) markedly suppressed the degradation of propranolol. Moreover, the iron in Fe(III)-citrate system was reused by a simple addition of citrate to the reaction solution. By GC-MS analysis, the photoproducts of the propranolol were identified and the degradation pathway was proposed. This work suggests that Fe(III)-citrate complexes are good alternative for the advanced treatment of organic pollutants at neutral pH in aqueous solution.
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: Zizheng
authors.initials: Z
authors.lastname: Liu
authors.forename: Zongping
authors.initials: Z
authors.lastname: Wang
authors.forename: Miaomiao
authors.initials: M
authors.lastname: Xue
authors.forename: Xianchen
authors.initials: X
authors.lastname: Zhu
authors.forename: Tao
authors.initials: T
authors.lastname: Tao
mesh_terms: D002851:Chromatography, High Pressure Liquid; D002951:Citrates / Q000737:chemistry*; D005290:Ferric Compounds / Q000737:chemistry*; D008401:Gas Chromatography-Mass Spectrometry; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D010777:Photochemistry; D011433:Propranolol / Q000737:chemistry*; D017382:Reactive Oxygen Species / Q000737:chemistry
chemical_list: D002951:Citrates; D005290:Ferric Compounds; D017382:Reactive Oxygen Species; D011433:Propranolol