Consideration on modeling of Nb sorption onto clay minerals
| Autor: | Ko Hemmi, Tetsuji Yamaguchi, Asako Shimada, Toshikatsu Maeda, Yoshihisa Iida, Logan Barr, Saki Ohira |
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| Rok vydání: | 2020 |
| Předmět: |
Aqueous solution
Chemistry Sorption 010501 environmental sciences engineering.material 010403 inorganic & nuclear chemistry 01 natural sciences 0104 chemical sciences Chemical state Chemical engineering Silicate minerals Illite engineering Physical and Theoretical Chemistry Solubility Clay minerals 0105 earth and related environmental sciences Waste disposal |
| Zdroj: | Radiochimica Acta. 108:873-877 |
| ISSN: | 2193-3405 0033-8230 |
| DOI: | 10.1515/ract-2020-0006 |
| Popis: | Sorption distribution coefficient (Kd) of niobium-94 on minerals are an important parameter in safety assessment of intermediate-depth disposal of waste from core internals etc. The Kd of Nb on clay minerals in Ca(ClO4)2 solutions were, however, not successfully modeled in a previous study. The high distribution coefficients of Nb on illite in Ca(ClO4)2 solutions were successfully reproduced by taking Ca–Nb–OH surface species into account. Solubility of Nb was studied in Ca(ClO4)2 solutions and the results were reproduced by taking an aqueous Ca–Nb–OH complex species, CaNb(OH)6 +, into account in addition to previously reported Nb(OH)6 − and Nb(OH)7 2−. Based on this aqueous speciation model, the Ca–Nb–OH surface species responsible for the sorption of Nb on illite in Ca(ClO4)2 solutions was presumed to be X_OCaNb(OH)6. Although uncertainties exist in the speciation of aqueous Ca–Nb–OH species, the result of this study proposed a possible mechanism for high distribution coefficient of Nb on illite in Ca(ClO4)2 solutions. The mechanism includes Ca–Nb–OH complex formation in aqueous, solid and surface phases. |
| Databáze: | OpenAIRE |
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