title: Photocatalytic and photoelectrocatalytic degradation of the drug omeprazole on nanocrystalline titania films in alkaline media: Effect of applied electrical bias on degradation and transformation products.
abstract: Photocatalytic and photoelectrocatalytic degradation of the drug omeprazole has been studied in the presence of nanocrystalline titania films supported on glass slides or transparent FTO electrodes in alkaline environment. Its photocatalytic degradation rate was assessed by its UV absorbance and by HPLC, while its transformation products were analyzed by HR-LC-MS. Based on UV absorbance, omeprazole can be photocatalytically degraded at an average rate of 6.7×10(-4)min(-1) under low intensity UVA irradiation of 1.5mWcm(-2) in the presence of a nanoparticulate titania film. This corresponds to degradation of 1.4mg of omeprazole per gram of the photocatalyst per liter of solution per hour. The photodegradation rate can be accelerated in a photoelectrochemical cell by applying a forward bias. In this case, the maximum rate reached under the present conditions was 11.6×10(-4)min(-1) by applying a forward bias of +0.6V vs. Ag/AgCl. Four major transformation products were successfully identified and their profiles were followed by HR-LC-MS. The major degradation path includes the scission of the sulfoxide bridge into the corresponding pyridine and benzimidazole ring derivates and this is accompanied by the release of sulfate anions in the reaction mixture.
authors: Department of Chemical Engineering, University of Patras, Caratheodory 1, University Campus, GR-26504 Patras, Greece.
authors: Iosif
authors: I
authors: Tantis
authors: Department of Physics and Astronomy, King Saud University, Riyadh, Saudi Arabia; Department of Automation Engineering, Technological Educational Institute of Pireaus, GR-12244 Athens, Greece.
authors: Leda
authors: L
authors: Bousiakou
authors: Department of Chemical Engineering, University of Patras, Caratheodory 1, University Campus, GR-26504 Patras, Greece.
authors: Zacharias
authors: Z
authors: Frontistis
authors: Department of Chemical Engineering, University of Patras, Caratheodory 1, University Campus, GR-26504 Patras, Greece.
authors: Dionissios
authors: D
authors: Mantzavinos
authors: Department of Environmental and Natural Resources Management, University of Patras, GR-30100 Agrinio, Greece.
authors: Ioannis
authors: I
authors: Konstantinou
authors: Department of Environmental and Natural Resources Management, University of Patras, GR-30100 Agrinio, Greece.
authors: Maria
authors: M
authors: Antonopoulou
authors: Department of Medical Laboratories Technology, Technological Educational Institute of Athens, 12210 Athens, Greece.
authors: George-Albert
authors: GA
authors: Karikas
authors: Department of Chemical Engineering, University of Patras, Caratheodory 1, University Campus, GR-26504 Patras, Greece; FORTH/ICE-HT, P.O. Box 1414, GR-26504 Patras, Greece. Electronic address: lianos@upatras.gr.
authors: Panagiotis
authors: P
authors: Lianos
mesh_terms: D000897:Anti-Ulcer Agents / Q000737:chemistry; D002384:Catalysis; D004563:Electrochemistry; D004566:Electrodes; D006863:Hydrogen-Ion Concentration; D053758:Nanoparticles / Q000737:chemistry / Q000528:radiation effects; D009853:Omeprazole / Q000737:chemistry*; D010782:Photolysis; D054328:Proton Pump Inhibitors / Q000737:chemistry; D012834:Silver / Q000737:chemistry; D014025:Titanium / Q000737:chemistry / Q000528:radiation effects; D014466:Ultraviolet Rays; D014874:Water Pollutants, Chemical / Q000737:chemistry*
chemical_list: D000897:Anti-Ulcer Agents; D054328:Proton Pump Inhibitors; D014874:Water Pollutants, Chemical; C009495:titanium dioxide; D012834:Silver; D014025:Titanium; D009853:Omeprazole
keywords: Omeprazole; Photocatalysis; Photoelectrocatalysis; TiO(2) films; Transformation products