Influence of urotropin on the precipitation of iron oxides from FeCl3 solutions

Šarić, Ankica; Musić, Svetozar; Nomura, Kiyoshi; Popović, Stanko (1998) Influence of urotropin on the precipitation of iron oxides from FeCl3 solutions. Croatica Chemica Acta, 71 (4). pp. 1019-1038. ISSN 0011-1643

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Abstract

Precipitations of iron oxides from FeCl3 solutions in the presence of urotropin at 90 degrees C were monitored using the Fourier transform infrared spectroscopy, Mossbauer spectroscopy, X-ray diffraction and transmission electron microscopy. Urotropin was used as a generator of OH- ions. The precipitation processes depended on the concentrations of FeCl3 and urotropin and the time of aging. After 1 day of aging the precipitation systems up to pH approximate to 2, the beta-FeOOH phase was precipitated, while in the region of 5 < pH < 6 the mixtures of beta-FeOOH, alpha-Fe2O3 and alpha-FeOOH were precipitated, and at pH > 6 the mixtures of alpha-Fe2O3 and alpha-FeOOH were observed. The beta-FeOOH phase precipitated at 2.16 < pH < 5.55 dissolved after 7 days, yielding soluble iron for the alpha-FeOOH growth on account of alpha-Fe2O3. At pH approximate to 1.5 and less, beta-FeOOH was present as a single phase up to 7 days of aging the precipitation systems. The mechanisms of iron oxide precipitation in dependence on pH were discussed. The size and morphology of oxide particles were strongly influenced by experimental conditions of the precipitation process as shown by transmission electron microscopy.

Item Type:

Article

Uncontrolled Keywords:

beta-feooh; structural-properties; water solutions; akaganeite; particles; hydrolysis; hematite; mossbauer; ions; transformation

Subjects:

NATURAL SCIENCES > Chemistry

Divisions:

Division of Materials Chemistry

Projects: