Sherriff, Nick, Issa, Ragiab, Morris, Katherine, Livens, Francis, Heath, Sarah, Bryan, Nick (2015) Reversibility in radionuclide/bentonite bulk and colloidal ternary systems. Mineralogical Magazine, 79 (6) 1307-1315 doi:10.1180/minmag.2015.079.06
| Reference Type | Journal (article/letter/editorial) | ||
|---|---|---|---|
| Title | Reversibility in radionuclide/bentonite bulk and colloidal ternary systems | ||
| Journal | Mineralogical Magazine | ||
| Authors | Sherriff, Nick | Author | |
| Issa, Ragiab | Author | ||
| Morris, Katherine | Author | ||
| Livens, Francis | Author | ||
| Heath, Sarah | Author | ||
| Bryan, Nick | Author | ||
| Year | 2015 (November) | Volume | 79 |
| Issue | 6 | ||
| Publisher | Mineralogical Society | ||
| DOI | doi:10.1180/minmag.2015.079.06Search in ResearchGate | ||
| Generate Citation Formats | |||
| Mindat Ref. ID | 244700 | Long-form Identifier | mindat:1:5:244700:5 |
| GUID | 0 | ||
| Full Reference | Sherriff, Nick, Issa, Ragiab, Morris, Katherine, Livens, Francis, Heath, Sarah, Bryan, Nick (2015) Reversibility in radionuclide/bentonite bulk and colloidal ternary systems. Mineralogical Magazine, 79 (6) 1307-1315 doi:10.1180/minmag.2015.079.06 | ||
| Plain Text | Sherriff, Nick, Issa, Ragiab, Morris, Katherine, Livens, Francis, Heath, Sarah, Bryan, Nick (2015) Reversibility in radionuclide/bentonite bulk and colloidal ternary systems. Mineralogical Magazine, 79 (6) 1307-1315 doi:10.1180/minmag.2015.079.06 | ||
| Abstract/Notes | AbstractTernary systems of 152Eu(III), bulk bentonite and ethylenediaminetetraacetic acid (EDTA) ([Eu] = 7.9 × 10–10 M; pH = 6.0–7.0) have been studied. Without EDTA, there was slow uptake in a two-stage process, with initial rapid sorption of Eu(III) (96%), followed by slower uptake of a much smaller fraction (3.0% over a period of one month). The reversibility of Eu(III) binding was tested by allowing Eu(III) to sorb to bentonite for 1–322 days. EDTA was added to the pre-equilibrated Eu bentonite systems at 0.01 M, a concentration that was sufficient to suppress sorption in a system where EDTA was present prior to the contact of Eu(III) with bentonite. A fraction of the Eu was released instantaneously (30–50%), but a significant amount remained bound. With time, the amount of Eu(III) retained by the bentonite reduced, with a slow fraction dissociation rate constant of approximately 4.3 × 10–8 s–1 (values in the range 2.2 × 10–8 – 1.0 × 10–7 s–1) for pre-equilibration times ≥7 days. Eventually, the amount of Eu(III) remaining bound to the bentonite was within error of that when EDTA was present prior to contact (4.5% ± 0.6), although in systems with pre-equilibration times >100 days, full release took up to 500 days. Europium interactions with colloidal bentonite were also studied, and the dissociation rate constant measured by a resin competition method. For the colloids, more Eu was found in the slowly dissociating fraction (60–70%), but the first-order dissociation rate constant was faster, with an average rate constant of 8.8 × 10–7 s–1 and a range of 7.7 × 10–7 –9.5 × 10–7 s–1. For both bulk and colloidal bentonite, although slow dissociation was observed for Eu(III), there was no convincing evidence for 'irreversible' binding. | ||
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