TY - JOUR
T1 - Precipitation pathways for ferrihydrite formation in acidic solutions
AU - Zhu, Mengqiang
AU - Frandsen, Cathrine
AU - Wallace, Adam F.
AU - Legg, Benjamin
AU - Khalid, Syed
AU - Zhang, Hengzhong
AU - Mørup, Steen
AU - Banfield, Jillian F.
AU - Waychunas, Glenn A.
N1 - Funding Information:
The work was supported by the U.S. Department of Energy, Office of Basic Energy Sciences, under Award Number DE-AC02-05CH11231 to Lawrence Berkeley National laboratory. M.Z. also thanks the partial support from the U.S. National Science Foundation under Grant EAR-1529937. C.F. acknowledges funding from the Danish council for independent research. Use of the National Synchrotron Light Source, Brookhaven National Laboratory was supported by the U.S. DOE Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-98CH10886. This research used resources of the Advanced Photon Source, a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contract No. DE-AC02-06CH11357. Use of the Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, is supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Contract No. DE-AC02-76SF00515.
Publisher Copyright:
© 2015.
PY - 2016/1/1
Y1 - 2016/1/1
N2 - Iron oxides and oxyhydroxides form via Fe3+ hydrolysis and polymerization in many aqueous environments, but the pathway from Fe3+ monomers to oligomers and then to solid phase nuclei is unknown. In this work, using combined X-ray, UV-vis, and Mössbauer spectroscopic approaches, we were able to identify and quantify the long-time sought ferric speciation over time during ferric oxyhydroxide formation in partially-neutralized ferric nitrate solutions ([Fe3+]=0.2M, 1.82O)63+, μ-oxo aquo dimers and ferrihydrite, and that with time, the μ-oxo dimer decreases while the other two species increase in their concentrations. No larger Fe oligomers were detected. Given that the structure of the μ-oxo dimer is incompatible with those of all Fe oxides and oxyhydroxides, our results suggest that reconfiguration of the μ-oxo dimer structure occurs prior to further condensation leading up to the nucleation of ferrihydrite. The structural reconfiguration is likely the rate-limiting step involved in the nucleation process.
AB - Iron oxides and oxyhydroxides form via Fe3+ hydrolysis and polymerization in many aqueous environments, but the pathway from Fe3+ monomers to oligomers and then to solid phase nuclei is unknown. In this work, using combined X-ray, UV-vis, and Mössbauer spectroscopic approaches, we were able to identify and quantify the long-time sought ferric speciation over time during ferric oxyhydroxide formation in partially-neutralized ferric nitrate solutions ([Fe3+]=0.2M, 1.82O)63+, μ-oxo aquo dimers and ferrihydrite, and that with time, the μ-oxo dimer decreases while the other two species increase in their concentrations. No larger Fe oligomers were detected. Given that the structure of the μ-oxo dimer is incompatible with those of all Fe oxides and oxyhydroxides, our results suggest that reconfiguration of the μ-oxo dimer structure occurs prior to further condensation leading up to the nucleation of ferrihydrite. The structural reconfiguration is likely the rate-limiting step involved in the nucleation process.
UR - https://www.scopus.com/pages/publications/84944937805
U2 - 10.1016/j.gca.2015.09.015
DO - 10.1016/j.gca.2015.09.015
M3 - Article
AN - SCOPUS:84944937805
SN - 0016-7037
VL - 172
SP - 247
EP - 264
JO - Geochimica et Cosmochimica Acta
JF - Geochimica et Cosmochimica Acta
ER -