Synthesis of Iron Nanomaterials for Environmental Applications from Hydrometallurgical Liquors

Hydrometallurgical leaching solutions are often rich in iron, which was traditionally considered a major impurity. However, iron can be selectively separated and recovered by applying appropriate solvent extraction and stripping techniques, and the resulting solutions can be valorized for the synthe...

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Bibliographic Details
Published in:Minerals (Basel) 2022-04, Vol.12 (5), p.556
Main Authors: Mystrioti, Christiana, Papassiopi, Nymphodora, Xenidis, Anthimos
Format: Article
Language:English
Subjects:
Cations
Chloride
Chromium
Hydrometallurgy
Iron oxides
Leaching
Magnetic properties
Magnetic resonance imaging
Magnetic saturation
Magnetite
Metals
Nanomaterials
Nanoparticles
Nanotechnology
Oxidation
Reagents
Saturation
Solvent extraction
Solvent extraction processes
Sulphates
Synthesis
Water treatment
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Summary:Hydrometallurgical leaching solutions are often rich in iron, which was traditionally considered a major impurity. However, iron can be selectively separated and recovered by applying appropriate solvent extraction and stripping techniques, and the resulting solutions can be valorized for the synthesis of high-added-value products, such as magnetic iron oxide nanoparticles (mIONPs). The aim of this study was to synthesize high-quality mIONPs from solutions simulating the composition of two alternative stripping processes. The precursor solutions consisted of Fe(II) in an acidic sulfate environment and Fe(III) in an acidic chloride medium. The Fe(II)-SO4 solution was treated with a mixture of KNO3-KOH reagents, and the product (M(II)) was identified as pure magnetite with a high specific magnetization of 95 emu·g−1. The treatment of Fe(III)-Cl solution involved the partial reduction of Fe(III) using metallic iron and the co-precipitation of iron cations with base addition combined with microwave-assisted heating. The product (M(III)) was a powder, which consisted of two phases, e.g., maghemite (75%) and magnetite (25%), and also had a high magnetic saturation of 80 emu·g−1. The nanopowders were evaluated for their effectiveness in removing Cr(VI) from contaminated waters. The maximum adsorption capacity was found to be equal to 11.4 and 17.4 mg/g for M(II) and M(III), respectively. The magnetic nanopowders could be easily separated from treated waters, a property that makes them promising materials for the water treatment sector.
ISSN:2075-163X
2075-163X
DOI:10.3390/min12050556