title: UV and solar photo-degradation of naproxen: TiO₂ catalyst effect, reaction kinetics, products identification and toxicity assessment.
abstract: Direct photolysis and TiO2-photocatalytic degradation of naproxen (NPX) in aqueous solution were studied using a UV lamp and solar irradiation. The degradation of NPX was found to be in accordance with pseudo-first order kinetics, the photocatalytic process being more efficient than photolysis. The NPX removal by photolysis (pHinitial 6.5) was 83% after 3h, with 11% of chemical oxygen demand (COD) reduction, whereas the TiO2-UV process led to higher removals of both NPX (98%) and COD (25%). The apparent pseudo-first-order rate constant (kapp) for NPX degradation by photolysis ranged from 0.0050 min(-1) at pH 3.5 to 0.0095 min(-1) at pH 6.5, while it was estimated to be 0.0063 min(-1) under acidic conditions in photocatalysis, increasing by 4-fold at pH 6.5. Ultra High Performance Liquid chromatography (UHPLC) coupled with a triple quadrupole detector and also a hybrid mass spectrometer which combines the linear ion trap triple quadrupole (LTQ) and OrbiTrap mass analyser, were used to identify NPX degradation products. The main intermediates detected were 1-(6-methoxynaphtalene-2-yl) ethylhydroperoxide, 2-ethyl-6-methoxynaphthalene, 1-(6-methoxynaphtalen-2-yl) ethanol, 1-(6-methoxynaphtalen-2-yl) ethanone and malic acid. Solar photocatalysis of NPX showed COD removals of 33% and 65% after 3 and 4h of treatment, respectively, and some reduction of acute toxicity, evaluated by the exposure of Eisenia andrei to OECD soils spiked with NPX-treated solutions.
authors.affiliation: University of Sfax, Laboratory of Water, Energy and Environment, National School of Engineers of Sfax (ENIS), Route de Soukra Km 3.5, PO Box 1173, 3038 Sfax, Tunisia.
authors.forename: Nabil
authors.initials: N
authors.lastname: Jallouli
authors.affiliation: University of Gafsa, Research Unit of Materials, Environment and Energy, Campus Universitaire Sidi Ahmed Zarroug, 2112 Gafsa, Tunisia.
authors.forename: Kais
authors.initials: K
authors.lastname: Elghniji
authors.affiliation: University of Sfax, Laboratory of Water, Energy and Environment, National School of Engineers of Sfax (ENIS), Route de Soukra Km 3.5, PO Box 1173, 3038 Sfax, Tunisia; Higher Institute of Biotechnology of Sfax (ISBS), Route de Soukra Km 3, 5 PO Box 1175, 3038 Sfax, Tunisia.
authors.forename: Olfa
authors.initials: O
authors.lastname: Hentati
authors.affiliation: LCM - Laboratory of Catalysis and Materials - Associate Laboratory LSRE-LCM, Faculdade de Engenharia, Universidade do Porto, Rua Dr. Roberto Frias, 4200-465 Porto, Portugal.
authors.forename: Ana R
authors.initials: AR
authors.lastname: Ribeiro
authors.affiliation: LCM - Laboratory of Catalysis and Materials - Associate Laboratory LSRE-LCM, Faculdade de Engenharia, Universidade do Porto, Rua Dr. Roberto Frias, 4200-465 Porto, Portugal.
authors.forename: Adrián M T
authors.initials: AM
authors.lastname: Silva
authors.affiliation: University of Sfax, Laboratory of Water, Energy and Environment, National School of Engineers of Sfax (ENIS), Route de Soukra Km 3.5, PO Box 1173, 3038 Sfax, Tunisia; Higher Institute of Biotechnology of Sfax (ISBS), Route de Soukra Km 3, 5 PO Box 1175, 3038 Sfax, Tunisia. Electronic address: mohamed.ksibi@isbs.rnu.tn.
authors.forename: Mohamed
authors.initials: M
authors.lastname: Ksibi
mesh_terms: D000818:Animals; D002384:Catalysis; D002851:Chromatography, High Pressure Liquid; D007700:Kinetics; D013058:Mass Spectrometry; D009288:Naproxen / Q000737:chemistry* / Q000633:toxicity; D009835:Oligochaeta / Q000187:drug effects; D010782:Photolysis; D012989:Soil Pollutants / Q000633:toxicity; D013472:Sunlight; D014025:Titanium / Q000737:chemistry* / Q000528:radiation effects*; D014466:Ultraviolet Rays; D014874:Water Pollutants, Chemical / Q000737:chemistry* / Q000633:toxicity
chemical_list: D012989:Soil Pollutants; D014874:Water Pollutants, Chemical; C009495:titanium dioxide; D009288:Naproxen; D014025:Titanium
keywords: Acute toxicity; Chemical oxygen demand (COD); Naproxen; Photocatalysis; Photolysis