The synthesis and microstructure of goethite particles precipitated in highly alkaline media

Iron choline citrate was used as the starting chemical in the synthesis of long goethite rods in highly alkaline media. Goethite particles were characterized by 57Fe Mössbauer, XRD, FT-IR, UV/Vis/NIR and FE-SEM. The phase composition and morphology of goethite particles did not change for up to 14 days of heating their suspension at 90 °C. However, upon autoclaving the suspension at 160 °C, the phase transformation goethite → hematite occurred through the dissolution/recrystallization mechanism, as confirmed by FE-SEM. Upon heating the goethite particles in air at 300 °C for 2–4 h hematite was formed with a preserved morphology of the original goethite particles. The hematite particles formed at 800 °C showed a changes in morphology due to the common effect of the solid-state rearrangement involving a loss of residual OH groups and sintering.

► Iron choline citrate was used for first time in “wet” synthesis of goethite.
► The microstructure of long goethite rods was stable at 90 °C.
► At 160 °C, goethite suspension transformed to hematite by dissolution/recrystallization.
► A certain advantage in phase analysis of Mössbauer spectroscopy to XRD was shown.
► The morphology of goethite rods was preserved in hematite produced in air at 300 °C.