Interactions between hydro-soluble degradation products from a radio-oxidized polyesterurethane and Eu(III) in contexts of repositories for low and intermediate level radioactive waste
Résumé
The complexation of Eu(III) by hydro-soluble degradation products (HDPs) from a radio-oxidized polyesterurethane is investigated. The polyesterurethane Estane 5703 ® (PURe) is radio-oxidized at 1000 kGy with γ-rays at room temperature. The polymer is then hydrolysed by a simplified artificial cement pore water solution (pH 13.3) for 31 days at 60 °C. The HDPs within the leachate are characterized using gas chromatography-mass spectrometry, ionic chromatography, and TOC analyser. The complexation of Eu(III) is studied by time-resolved luminescence spectroscopy (TRLS). The main HDPs are adipic acid-hexane-1,6-dioic acid-and butane-1,4-diol. Unlike HDPs from non-irradiated PURe, the HDPs from 1000 kGy γ-irradiated PURe do form complexes with Eu(III) at pH 13.3. Neither adipate nor butane-1,4-diol are responsible for this complexation. The existence of several types of complexes is evidenced by TRLS and electrospray ionization mass spectroscopy (ESI-MS): complexation reactions and operational constants are proposed. The complexes formed at high pH (from 10 to 13) are different from the lower pH complexes. The lower pH complexes are studied by ESI-MS and two ligands are identified: adipate and an oligomer.
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