Effects of ozone pre-treatment on diclofenac: Intermediates, biodegradability and toxicity assessment |
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Authors: | Alessandra D Coelho Ana Agüera Santiago Esplugas |
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Affiliation: | a Programa de Engenharia Química - COPPE, UFRJ, CP 68502, 21941-972, Rio de Janeiro, Brazil b Departament d'Enginyeria Química. Universitat de Barcelona, Martí i Franquès 1, 08028 Barcelona, Spain c Pesticide Residue Research Group, Faculty of Sciences, University of Almería, 04071 Almería, Spain |
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Abstract: | Diclofenac (DCF), a common analgesic, anti-arthritic and anti-rheumatic drug, is one of the most frequently detected compounds in water. This study deals with the degradation of diclofenac in aqueous solution by ozonation. Biodegradability (BOD5/COD ratio and Zahn-Wellens test), acute ecotoxicity and inhibition of activated sludge activity were determined in ozonated and non-ozonated samples. Liquid chromatography coupled with time-of-flight mass spectrometry (LC/TOF-MS) was used to identify the intermediates formed in 1 h of ozonation. Eighteen intermediates were identified by these techniques and a tentative degradation pathway for DCF ozonation is proposed.Experimental results show that ozone is efficient at removing DCF: > 99% removal (starting from an initial concentration of 0.68 mmol L− 1) was achieved after 30 min of ozonation (corresponding to an absorbed ozone dose of 0.22 g L− 1, which is 4.58 mmol L− 1). However, only 24% of the substrate was mineralized after 1 h of ozonation. The biodegradability, respiration inhibition in activated sludge and acute toxicity tests demonstrate that ozonation promotes a more biocompatible effluent of waters containing DCF. |
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Keywords: | Diclofenac Ozonation Intermediates Biodegradability Toxicity Inhibition |
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