Abstract
The ability to simultaneously monitor the flux of iron atoms within the solution and solid phases can provide considerable insight into mechanisms of iron oxide mineral transformations. The autocatalytic interaction between hematite and Fe(ii)-oxalate has long been of interest for its environmental and industrial relevance. In this study we take advantage of iron isotopic labelling and mass-sensitive imaging at the single particle scale to determine how changes in solution composition correlate with the morphologic evolution of faceted, micrometer-sized hematite platelets. Net dissolution is confirmed through analyses of aqueous iron chemistry, as well as by quantitative atomic force microscopy. Isotopic mapping techniques show that Fe(ii) readily adsorbs to (001) and (012) surfaces in the absence of oxalate, but when oxalate is present selective dissolution of the (001) surface prevails and Fe deposition via recrystallization is not observed. Comparison between particle microtopographies following reaction with Fe(ii), oxalate, and Fe(ii)-oxalate show substantially different behaviors, consistent with distinct mechanisms of interaction with hematite surfaces. The extensive characterization conducted on the coupled solution/solid dynamics in this system provides new insight for distinguishing crystal growth, dissolution, and recrystallization processes.
| Original language | English |
|---|---|
| Pages (from-to) | 1979-1992 |
| Number of pages | 14 |
| Journal | Environmental Science: Nano |
| Volume | 12 |
| Issue number | 3 |
| DOIs | |
| State | Published - Jan 24 2025 |
Funding
This material is based upon work supported by the U.S. Department of Energy (DOE), Office of Science, Basic Energy Sciences (BES), Chemical Sciences, Geosciences, and Biosciences Division through its Geosciences Program at Pacific Northwest National Laboratory (PNNL) (FWP 56674). A portion of the work was performed in the Environmental and Molecular Sciences Laboratory (EMSL), a national scientific user facility at PNNL sponsored by the DOE's Office of Biological and Environmental Research, under user proposals https://doi.org/10.46936/lser.proj.2020.51382/60000186 and https://doi.org/10.46936/lser.proj.2021.51922/60000373. PNNL is a multi-program national laboratory operated by Battelle Memorial Institute under contract number DE-AC05-76RL01830 for the DOE.