Low temperature hydrothermal synthesis and characterization of iron oxide powders of diverse morphologies from spent pickle liquor

Iron oxide nanoparticles (goethite and hematite) of various shapes have been synthesized through a simple
hydrothermal reaction from the stripped solution of Fe(III) obtained after extraction and separation of Zn
and Fe from spent pickle liquor. The influence of pH and synthesis time on the structure and morphology of
the as-prepared α-Fe2O3 are investigated. It was possible to control the particle size and shape by adjusting
the pH (2–12) of the starting solutions and time of synthesis (1–6 h). Under the appropriate conditions, rod-
like α-FeOOH (goethite) and hexagonal α-Fe2O3 (hematite) materials of the uniform nano-crystalline structure
were selectively synthesized in large quantities. The morphology and structure of the final products were inves-
tigated in detail by X-ray powder diffraction pattern (XRD), transmission electron microscopy (TEM), Raman
spectroscopy and vibrational sample magnetometer (VSM). The probable mechanism of formation of uniform
α-FeOOH and α-Fe2O3 nano-particles is discussed on the basis of the experimental results and characterization
studies. The evaluation of the magnetic property has established the weak ferromagnetism characteristics of both
goethite and hematite at room temperature.
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