Early stage time-resolved development of FeOOH nanoparticles from bicarbonate-neutralized Fe2(SO4)3 and Fe(NO3)3 solutions were investigated using SAXS, UV-VIS spectroscopy, in-situ XRD and Cryo-TEM. In Fe2(SO4)3 solutions, total particle volume, indicated by SAXS invariant, decreased with time before visual precipitation. UV-VIS spectra indicated that initially-formed particles were not iron oxyhydroxide. These particles gradually disappeared, with FeOOH-like particles emerging at longer times. Both SAXS and Cryo-TEM results indicated formation of 1-2 nm particles which quickly aggregated. In Fe(NO3)3 solutions, SAXS results indicated that both particle size (2-3 nm) and total particle volume undergo a steady increase with time, but with limited aggregation. In this case the UV-VIS spectra indicated particles of an FeOOH phase. XRD results imply that the FeOOH particles in sulfate and nitrate solutions were evolving towards schwertmannite and ferrihydrite, respectively. The observed differences between the two systems could be due to the stronger Fe-binding ability of sulfate.

Time-resolved study of early-stage formation of iron oxyhydroxide nanoparticles

242nd National Meeting (2011)

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