Ferrihydrite formation : the role of Fe13 Keggin clusters
Weatherill, Joshua Simon and Morris, Katherine and Bots, Pieter and Stawski, Tomasz M. and Janssen, Arne and Abrahamsen, Liam and Blackham, Richard and Shaw, Samuel (2016) Ferrihydrite formation : the role of Fe13 Keggin clusters. Environmental Science and Technology, 50 (17). pp. 9333-9342. ISSN 0013-936X (https://doi.org/10.1021/acs.est.6b02481)
Preview |
Text.
Filename: Weatherill_etal_EST2016_Ferrihydrite_formation_the_role_of_Fe13_Keggin_clusters.pdf
Final Published Version License: Download (6MB)| Preview |
Abstract
Ferrihydrite is the most common iron oxyhydroxide found in soil and is a key sequester of contaminants in the environment. Ferrihydrite formation is also a common component of many treatment processes for clean-up of industrial effluents. Here we characterize ferrihydrite formation during the titration of an acidic ferric nitrate solution with NaOH. In-situ SAXS measurements supported by ex situ TEM indicate that initailly Fe13 Keggin clusters (radius ~0.45 nm) form in solution at pH 0.5 - 1.5, and are persistant for at least 18 days. The Fe13 clusters begin to aggregate above ~ pH 1, initially forming highly linear structures. Above pH ~ 2 densification of the aggregates occurs in conjunction with precipiation of low molecular weight Fe(III) speices (e.g. monomers, dimers) to form mass fractal aggregates of ferrihydrite nanoparticles (~ 3 nm) in which the Fe13 Keggin motif is preserved. SAXS analysis indicates the ferrihydrite particles have a core-shell structure consisting of a Keggin center surrounded by a Fe-depleted shell, supporting the surface depleted model of ferrihydrite. Overall, we present the first direct evidence for the role of Fe13 clusters in the pathway of ferrihydrite formation during base hydrolysis, showing clear structural continuity from isolated Fe13 Keggins to the ferrihydrite particle structure. The results have direct relevance to the fundamental understanding of ferrihydrite formation in environmental, engineered and industrial processes.
ORCID iDs
Weatherill, Joshua Simon, Morris, Katherine, Bots, Pieter ORCID: https://orcid.org/0000-0001-6863-0648, Stawski, Tomasz M., Janssen, Arne, Abrahamsen, Liam, Blackham, Richard and Shaw, Samuel;-
-
Item type: Article ID code: 57292 Dates: DateEvent2 August 2016Published2 August 2016Published Online2 August 2016AcceptedSubjects: Technology > Engineering (General). Civil engineering (General) > Environmental engineering
Science > ChemistryDepartment: Faculty of Engineering > Civil and Environmental Engineering Depositing user: Pure Administrator Date deposited: 05 Aug 2016 08:51 Last modified: 08 Oct 2024 00:16 Related URLs: URI: https://strathprints.strath.ac.uk/id/eprint/57292