Reversibility of uranium and thorium binding on a modified bauxite refinery residue: the effects of aging temperature

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dc.contributor.authorClark, MWen_AU
dc.contributor.authorPayne, TEen_AU
dc.contributor.authorHarrison, JJen_AU
dc.contributor.authorComarmond, MJen_AU
dc.contributor.authorCollins, RNen_AU
dc.contributor.authorReichelt-Brushett, AJen_AU
dc.date.accessioned2023-01-12T00:31:15Zen_AU
dc.date.available2023-01-12T00:31:15Zen_AU
dc.date.issued2015-02en_AU
dc.date.statistics2022-11-03en_AU
dc.description.abstractThe effects of aging on the pH-dependence and reversibility of uranium and thorium binding by a modified bauxite refinery residue (MBRR) were studied in laboratory uptake/leaching experiments. Natural uranium and thorium isotopes (predominantly 238UVI and 232ThIV) of 0.4, and 0.2 mM were loaded for an 8-day period at the natural equilibrium pH of the MBRR (approximately 8.5) and were allowed to age for 6 months in humid sealed containers at 4, 23, and 65 °C. After aging, anthropogenic 232UVI and 229ThIV were added as exchange isotopes and the pH decreased stepwise from 8 to 3 over several hours in pH dependent experiments. The relative concentrations of the isotope pairs (i.e. 238UVI and 232UVI; 232ThIV and 229ThIV) indicated that irreversibility of UVI and ThIV binding by the MBRR increased with aging and was dependent on the aging temperature and surface actinide loading. Linear combination fitting of the EXAFS data for the uranium loaded materials indicated that at low uranium concentrations sorption to minerals (particularly hematite) was a prime uranium removal mechanism, but at higher concentrations precipitation dominated. The data suggest that increased irreversibility and incorporation of UVI during aging is associated with re-crystallisation of precipitates. © 2014 Elsevier Ltd.en_AU
dc.description.sponsorshipThis study was funded by the Australian Institute of Nuclear Science and Engineering grant AINGRA08087. We also acknowledge the funding provided by the Australian Synchrotron for the XAS work through the provision of the grant AS112/XAS/3643.en_AU
dc.identifier.citationClark, M. W., Payne, T. E., Harrison, J. J., Comarmond, M. J., Collins, R. N., & Reichelt-Brushett, A. J. (2015). Reversibility of uranium and thorium binding on a modified bauxite refinery residue: the effects of aging temperature. Applied Geochemistry, 53, 79-90. doi:10.1016/j.apgeochem.2014.12.011en_AU
dc.identifier.issn0883-2927en_AU
dc.identifier.journaltitleApplied Geochemistryen_AU
dc.identifier.pagination79-90en_AU
dc.identifier.urihttps://doi.org/10.1016/j.apgeochem.2014.12.011en_AU
dc.identifier.urihttps://apo.ansto.gov.au/dspace/handle/10238/14317en_AU
dc.identifier.volume53en_AU
dc.language.isoenen_AU
dc.publisherElsevieren_AU
dc.subjectUraniumen_AU
dc.subjectThoriumen_AU
dc.subjectBauxiteen_AU
dc.subjectAmbient temperatureen_AU
dc.subjectRefiningen_AU
dc.subjectRecrystallizationen_AU
dc.titleReversibility of uranium and thorium binding on a modified bauxite refinery residue: the effects of aging temperatureen_AU
dc.typeJournal Articleen_AU
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