RT Journal Article
T1 Metastability, nanocrystallinity and pseudo-solid solution effects on the understanding of schwertmannite solubility
A1 Caraballo Monge, Manuel Antonio
A1 Rimstidt, J. Donald
A1 Macías Suárez, Francisco
A1 Nieto Liñán, José Miguel
A1 Hochella Jr., Michel F.
AB The role of metastable nanocrystalline precursors, like schwertmannite, in iron and sulfate rich acidic waters iscommonly underestimated or even neglected. In addition to schwertmannite metastability, its heterogeneouschemical composition and the current use of disparate solubility products result in an incongruousunderstanding of this mineral. In order to characterize schwertmannite stability in acid mine drainage settings,we used coincident schwertmannite and solution samples to determine how its solubility product is related toits composition. The solubility products (as log Ksp) for 30 natural samples of this study span a range of log Kspvalues from 5.8 to 39.5. These values show a gradual distribution on the pH–pe space from pH 1.93 to 4.71 andpe values from8.5 to 13.7. A set of three predictive equations to select the best schwertmannite solubility productfor each new specific case study was obtained. This approximation allows generating an appropriate solubilityproduct for schwertmannite despite the lack of information in certain environments (e.g., absence of formerwater chemistries on Mars). The trend observed for Fe and S contents in schwertmannite can be interpreted asa pseudo-solid solution ranging from high to low S and Fe concentrations. The polyphasic nature ofschwertmannite was studied by means of a thermodynamic model assuming equilibrium between a hydrousferric oxide (HFO), schwertmannite, and solution. All the results obtained in this study support theunderstanding of schwertmannite as a polyphasic nanomineral and encourage using a broad log Ksp range tomodel the solubility of schwertmannite in nature
PB Elsevier
SN 0009-2541
YR 2013
FD 2013-10
LK https://hdl.handle.net/10272/23138
UL https://hdl.handle.net/10272/23138
LA eng
NO Caraballo, M. A., Rimstidt, J. D., Macías, F., Nieto, J. M., & Hochella, M. F., Jr. (2013). Metastability, nanocrystallinity and pseudo-solid solution effects on the understanding of schwertmannite solubility. In Chemical Geology (Vols. 360–361, pp. 22–31). Elsevier BV. https://doi.org/10.1016/j.chemgeo.2013.09.023
NO This study was financed by the Spanish Ministry of Science and Innovation through the project METODICA (Ref. CGL2010-21956-C02-02). M.A.C. was financially supported by the Spanish Ministry of Education and the Post-doctoral International Mobility Sub-programme I+D+i 2008–2011.
DS Repositorio Institucional de la Universidad de Huelva
RD 1 jun 2026