| Autor: |
Furcas, Fabio E., Lothenbach, Barbara, Mundra, Shishir, Borca, Camelia, Albert, Cristhiana C., Isgor, O. Burkan, Huthwelker, Thomas, Angst, Ueli M. |
| Rok vydání: |
2023 |
| Předmět: |
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| Zdroj: |
Environmental Science and Technology (2023), 57, 42, 16097-16108 |
| Druh dokumentu: |
Working Paper |
| DOI: |
10.1021/acs.est.3c05260 |
| Popis: |
The transformation of 2-line ferrihydrite to goethite from supersaturated solutions at alkaline pH >= 13.0 was studied using a combination of benchtop and advanced synchrotron techniques such as X-ray diffraction, thermogravimetric analysis and X-ray absorption spectroscopy. In comparison to the transformation rates at acidic to mildly alkaline environments, the half-life,t_1/2, of 2-line ferrihydrite reduces from several months at pH = 2.0, and approximately 15 days at pH = 10.0, to just under 5 hours at pH = 14.0. Calculated first order rate constants of transformation, k, increase exponentially with respect to the pH and follow the progression log_10 k = log_10 k_0 + a*pH^E3. Simultaneous monitoring of the aqueous Fe(III) concentration via inductively coupled plasma optical emission spectroscopy demonstrates that (i) goethite likely precipitates from solution and (ii) its formation is rate-limited by the comparatively slow re-dissolution of 2-line ferrihydrite. The analysis presented can be used to estimate the transformation rate of naturally occurring 2-line ferrihydrite in aqueous electrolytes characteristic to mine and radioactive waste tailings as well as the formation of corrosion products in cementitious pore solutions. |
| Databáze: |
arXiv |
| Externí odkaz: |
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