Formation of lepidocrocite (γ-FeOOH) from oxidation of nanoscale zero-valent iron (nZVI) in oxygenated water

Abstract

To assess the aquatic reactivity, toxicity, fate and transport of nanomaterials, it is essential to determine their transformations in terms of composition, morphology and surface characteristics in water. In this work, oxidation products of nanoscale zero-valent iron (nZVI) are characterized with spherical aberration corrected scanning transmission electron microscopy (Cs-STEM) integrated with selected area electron diffraction (SAED) and energy-dispersive X-ray spectroscopy (EDS). Crystalline structures from nZVI oxidation in oxygenated water are identified. The results of Cs-STEM, EDS, X-ray diffraction (XRD), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS) all prove that the main products are oxyhydroxides (FeOOH), notably lepidocrocite (γ-FeOOH).