Transformation of ferric compounds into iron oxides

Autor:	L.P. Sapolnova, L. P. Yermilova, A. I. Gorshkov, B. B. Zvyagin, F. V. Chukhrov
Rok vydání:	1977
Předmět:	Goethite Chemistry Inorganic chemistry Oxide Geology engineering.material Hematite chemistry.chemical_compound Ferrihydrite visual_art Jarosite medicine engineering visual_art.visual_art_medium Ferric Hydroxide Lepidocrocite medicine.drug
Zdroj:	International Geology Review. 19:766-774
ISSN:	1938-2839 0020-6814
DOI:	10.1080/00206817709471076
Popis:	Ferrihydrite (2.5 Fe2O2-4.5 H2O) is an unstable colloidal mineral. It dissolves in highly alkaline solutions and is precipitated from them in the form of goethite. Jarosite is stable at very low pH but is decomposed at higher values of pH with separation of iron oxides. Experiments show that in rapid decomposition of jarosite a protohematite substance, ferrihydrite, is formed. This transformation occurs at moderate pH values when solutions percolate through the aggregates of jarosite. Ferrihydrite, an unstable colloidal hydrated oxide of ferric iron, changes spontaneously to stable hematite with time. Very slow decomposition of jarosite results in its replacement by iron hydroxide, goethite. Under laboratory conditions in alkaline solutions lepidocrocite may be obtained from jarosite. The synthesis of this iron hydroxide passes through a stage of intermediate products: ferrihydrite and hydrated ferric oxide - ferriprotolepidocrocite, formed by solution of ferrihydrite in strongly alkaline solutions. The t...
Databáze:	OpenAIRE
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