Reaction of gadolinium chelates with ozone and hydroxyl radicals.
Environ Sci Technol
; 47(17): 9942-9, 2013 Sep 03.
Article
en En
| MEDLINE
| ID: mdl-23888885
ABSTRACT
Gadolinium chelates are used in increasing amounts as contrast agents in magnetic resonance imaging, and their fate in wastewater treatment has recently become the focus of research. Oxidative processes, in particular the application of ozone, are currently discussed or even implemented for advanced wastewater treatment. However, reactions of the gadolinium chelates with ozone are not yet characterized. In this study, therefore, rate constants with ozone were determined for the three commonly used chelates Gd-DTPA, Gd-DTPA-BMA, and Gd-BT-DO3A, which were found to be 4.8 ± 0.88, 46 ± 2.5, and 24 ± 1.5 M(-1) s(-1), respectively. These low rate constants indicate that a direct reaction with ozone in wastewater is negligible. However, application of ozone in wastewater leads to substantial yields of (â¢)OH. Different methods have been applied and compared for determination of k((â¢)OH+Gd chelate). From rate constants determined by pulse radiolysis experiments (k((â¢)OH+Gd-DTPA) = 2.6 ± 0.2 × 10(9) M(-1) s(-1), k((â¢)OH+Gd-DTPA-BMA) = 1.9 ± 0.7 × 10(9) M(-1) s(-1), k((â¢)OH+Gd-BT-DO3A) = 4.3 ± 0.2 × 10(9) M(-1) s(-1)), it is concluded that a reaction in wastewater via (â¢)OH radicals is feasible. Toxicity has been tested for educt and product mixtures of both reactions. Cytotoxicity (MTT test) and genotoxicity (micronuclei assay) were not detectable.
Texto completo:
1
Base de datos:
MEDLINE
Asunto principal:
Contaminantes Químicos del Agua
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Quelantes
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Eliminación de Residuos Líquidos
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Medios de Contraste
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Gadolinio
Tipo de estudio:
Evaluation_studies
Idioma:
En
Revista:
Environ Sci Technol
Año:
2013
Tipo del documento:
Article