Lepidocrocite characterization

Lepidocrocite is generally less widespread than its polymorph, goethite, but it does occur frequently as orange accumulations in certain environments. These are characterized by the presence of Fe from which lepidocrocite forms by oxidation. The presence of this mineral, therefore, in-... 

Thermal methods of analysis are often useful in the characterization of minerals, as described in Section 7.6.5. Aluminum hydroxides such as gibbsite show a mass loss of 34.6% on dehydroxylation thus, they show an important negative peak in DTA and a marked mass loss in TGA, and so these techniques are employed for both qualitative and quantitative characterization of these minerals. The same happens with iron hydroxides and oxohydroxides, such as goethite, lepidocrocite, and so on also, the presence of OH groups in otherwise thermally inert minerals such as hematite can be detected. 

Despite these limitations, the technique has been applied in the past to characterize the forms of iron occurring in different plants [62-65]. More recently, a detailed study of iron uptake and translocation in rice [66] grown in anaerobic FeCb-enriched nutrient solutions showed primarily the presence of Fe(lll) hydrous oxide components precipitated on the root cell wall (ferrihydrite and/or lepidocrocite). No evidence of Fe(ll) was found in the leaf tissue, the spectra were characteristic of Fe(lll) present in ferritin and in other complexed forms, not further identified by the authors. Iron biomineralization was also observed In a perennial grass grown in extreme acidic environment with a high content of metals [67,68]. In this case, the Mossbauer spectral analysis indicated that iron accumulated in this plant mainly as jarosite and ferrihydrite (ferritin). ]arosite accumulated In roots and rhizomes, while ferritin was detected in all the structures. 

P.M.A. de Bakker, E. Grave, R.E. Vandenberghe, L.H. Bowen, R.J. Pollard, R.M. Persoons, Mossbauer study of the thermal decomposition of lepidocrocite and characterization of the decomposition products. Phys. Chem. Miner. 18, 131-143 (1991)... 

Saito N., Haneda H., Li D., Koumoto K. Characterization of zinc oxide micropatterns deposited on self-assembled monolayer template. J. Ceram. Soc. Jpn. 2002 110 386-390 Santos L.R.B., Santilli C.V., Pulcinelli S.H. Sol-gel transition in Sn02 colloidal suspensions viscoelastic properties. J. Non-Cryat. Solid 1999 247 153-157 Santos L.R.B., Craievich A.F., Santilli C.V., Pulcinelli S.H. Sol phase and sol-gel transition in Sn02 colloidal suspensions. J. Appl. Cryst. 2000 33 609-613 Sasaki T., Watanabe M., Michiue Y., Komatsu Y., Izumi F., Takeuchi S. Preparation of acid-base properties of a protonated titanate with the lepidocrocite-like layer structure. Chem. Mater. 1995 7 1001-1007... 

A subsequent pubUcation characterized the surface film that developed on the steel after exposure to solutions containing these inhibitor compoimds. Attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy was used to identify the species present on the steel surface. The cotmnon steel corrosion product lepidocrocite (y-FeOOH) was not present on the surface, an indication that effective corrosion protection had occrrrred. At short exposure... 

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