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TitleIodinated contrast media electro-degradation: Process performance and degradation pathways
AbstractThe electrochemical degradation of six of the most widely used iodinated contrast media was investigated. Batch experiments were performed under constant current conditions using two DSA (R) electrodes (titanium coated with a proprietary and patented mixed metal oxide solution of precious metals such as iridium, ruthenium, platinum, rhodium and tantalum). The degradation removal never fell below 85% (at a current density of 64 mA/cm(2) with a reaction time of 150 min) when perchlorate was used as the supporting electrolyte; however, when sulphate was used, the degradation performance was above 80% (at a current density of 64 mA/cm(2) with a reaction time of 150 min) for all of the compounds studied. Three main degradation pathways were identified, namely, the reductive de-iodination of the aromatic ring, the reduction of alkyl aromatic amides to simple amides and the de-acylation of N-aromatic amides to produce aromatic amines. However, as amidotrizoate is an aromatic carboxylate, this is added via the decarboxylation reaction. The investigation did not reveal toxicity except for the lower current density used, which has shown a modest toxicity, most likely for some reaction intermediates that are not further degraded. In order to obtain total removal of the contrast media, it was necessary to employ a current intensity between 118 and 182 mA/cm(2) with energy consumption higher than 370 kWh/m(3). Overall, the electrochemical degradation was revealed to be a reliable process for the treatment of iodinated contrast media that can be found in contaminated waters such as hospital wastewater or pharmaceutical waste-contaminated streams. (C) 2014 Elsevier B.V. All rights reserved.
SourceScience of the total environment 506, pp. 631–643
KeywordsIodinated contrast mediaElectra-degradationBy-productsPharmaceutical wastewaterToxicity
JournalScience of the total environment
EditorElsevier, Lausanne ;, Paesi Bassi
Year2015
TypeArticolo in rivista
DOI10.1016/j.scitotenv.2014.10.115
AuthorsDel Moro Guido; Pastore Carlo; Di Iaconi Claudio; Mascolo Giuseppe
Text340131 2015 10.1016/j.scitotenv.2014.10.115 ISI Web of Science WOS 000347576800064 Scopus 2 s2.0 84922294157 ISI Web of Science WOS 000347576800064 Iodinated contrast media Electra degradation By products Pharmaceutical wastewater Toxicity Iodinated contrast media electro degradation Process performance and degradation pathways Del Moro Guido; Pastore Carlo; Di Iaconi Claudio; Mascolo Giuseppe Consiglio Nazionale delle Ricerche, Istituto di Ricerca Sulle Acque, Viale F. De Blasio 5, Bari 70132, Italy The electrochemical degradation of six of the most widely used iodinated contrast media was investigated. Batch experiments were performed under constant current conditions using two DSA R electrodes titanium coated with a proprietary and patented mixed metal oxide solution of precious metals such as iridium, ruthenium, platinum, rhodium and tantalum . The degradation removal never fell below 85% at a current density of 64 mA/cm 2 with a reaction time of 150 min when perchlorate was used as the supporting electrolyte; however, when sulphate was used, the degradation performance was above 80% at a current density of 64 mA/cm 2 with a reaction time of 150 min for all of the compounds studied. Three main degradation pathways were identified, namely, the reductive de iodination of the aromatic ring, the reduction of alkyl aromatic amides to simple amides and the de acylation of N aromatic amides to produce aromatic amines. However, as amidotrizoate is an aromatic carboxylate, this is added via the decarboxylation reaction. The investigation did not reveal toxicity except for the lower current density used, which has shown a modest toxicity, most likely for some reaction intermediates that are not further degraded. In order to obtain total removal of the contrast media, it was necessary to employ a current intensity between 118 and 182 mA/cm 2 with energy consumption higher than 370 kWh/m 3 . Overall, the electrochemical degradation was revealed to be a reliable process for the treatment of iodinated contrast media that can be found in contaminated waters such as hospital wastewater or pharmaceutical waste contaminated streams. C 2014 Elsevier B.V. All rights reserved. 506 Published version Articolo in rivista Elsevier 0048 9697 Science of the total environment Science of the total environment Sci. total environ. claudio.diiaconi DI IACONI CLAUDIO carlo.pastore PASTORE CARLO guido.delmoro DEL MORO GUIDO giuseppe.mascolo MASCOLO GIUSEPPE TA.P07.001.004 Trattamenti per il riutilizzo e per lo smaltimento dei fanghi di depurazione