Influence of Chloride on the Formation of Iron Oxides From Fe(II) Chloride. I. Effect of [Cl]/[Fe] on the Formation of Magnetite

Abstract

Abstract--The formation of fine-grained magnetite (t0.1 #m) at pH 7 and 25~ from aeration of Fe(II) chloride solutions is presented. The magnetite converted at 105~ to maghemite with poorly developed superstructure lines. Under the experimental conditions employed, as the initial [C1]/[Fe] ratio was increased from the stoichiometric value of 2, the final product contained increasing amounts oflepidocrocite. The degree ofcrystallinity of this phase, as measured by the width at half height of the 020 X-ray diffraction peak, also increased with this ratio. The hydrolysis rate (base consumption to maintain pH) showed a plateau whose position and extent changed with the initial [C1]/[Fe] ratio. Through this plateau region the Eh decreased to a minimum value the position of which was directly related to the [C1]/[Fe] value. The formation of lepidocrocite rather than magnetite is likely due to the high [C1] where there would be increased difficulty for neighboring OH to condense and eliminate HE0. The formation of Fe-O-Fe bonds in this condensation would be impeded by C1 substitution for OH either in the first formed green rust stage or during its oxidation.

Desalination of Water Using ZVI (Fe0)

“…The desalination is associated with changes in Eh ( Figures C5 and C14). Changes in Eh reflect changes in the rate of hydrolysis, where decreases in Eh represent increased hydrolysis, and increases in Eh represent reduced hydrolysis [67]. They indicate that NaCl removal is associated with the OH radical and related species (e.g., HO2 − ) [67].…”

“…Changes in Eh reflect changes in the rate of hydrolysis, where decreases in Eh represent increased hydrolysis, and increases in Eh represent reduced hydrolysis [67]. They indicate that NaCl removal is associated with the OH radical and related species (e.g., HO2 − ) [67]. This is confirmed by the [at+1] analysis in Table 2 where hydrolysis improves the effective NaCl removal efficiency of a Type B pre-treatment by 25%, and a Type C pretreatment by 500%.…”

“…where R = gas constant It follows from Equation (67), that if the temperature changes, then K, ΔE, ΔG, ΔH, ΔS are also known for the new temperature at a constant pH. ΔE 0 which is defined at pH = 0, can be redefined for the pH observed in the water at time t, where for a reaction converting one ion to another the observed Eh indicates [19] …”

ZVI (Fe0) Desalination: Stability of Product Water

“…, ferrous hydroxychloride, e.g., [54][55][56][57][58][59][60][61]. The Na + and Cl´ions are concentrated within the layered molecular structure [54][55][56][57][58][59][60][61].…”

Red ochre decorations in Spanish Neolithic ceramics: a mineralogical and technological study

“…In soils, maghemite usually forms by heating (bush fires, undergrowth and forest fires) of iron oxihydroxides (goethite, lepidocrocite, ferrihydrite) in the presence of organic matter. In such cases maghemite is poorly crystallised and can show isomorphic aluminium replacement [24,25,28].…”