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Mineralogy of precipitates formed from mine effluents in Finland
Published in A.A. Balkema, Tailings and Mine Waste 2000, 2022
Liisa Carlson, Sirpa Kumpulainen
Thiobacillus ferrooxidans. Goethite can be formed directly or through transformation of other compounds via solution. Two dissolved species contribute to the formation of goethite from solution. SO4 at pH < 6 and concentrations < 1000 mg/L, and HCO3 at pH > 6 are known from laboratory experiments to favor the crystallization of goethite (Carlson and Schwertmann, 1990). Ferrihydrite can only be formed at pH > 5 in the presence of dissolved silica. Organic compounds may contribute to its formation, too (Schwertmann et al., 1984). Lepidocrocite has surprisingly been observed in mine drainage environments (Blowes et al., 1994, Milnes et al., 1992). In laboratory experiments many common impurities, such as dissolved silica, sulfate, or bicarbonate prevent its formation. According to Bigham (personal communication) a small amount of lepidocrocite was observed in mixture with other iron oxides in an abandoned coal mine in USA. As soon as no more dissolved oxygen could be measured, lepidocrocite disappeared.
Iron Nanoparticles for Contaminated Site Remediation and Environmental Preservation
Published in Alok Dhawan, Sanjay Singh, Ashutosh Kumar, Rishi Shanker, Nanobiotechnology, 2018
Adam Truskewycz, Sayali Patil, Andrew Ball, Ravi Shukla
Lepidocrocite is generally regarded as paramagnetic; however, at extremely low temperatures (52 K), it can become antiferromagnetic (Hirt and Lanci 2011). It has an edge-shared octahedral structure and is relatively unstable under aerobic conditions favoring the formation of Goethite (Chesworth et al. 2008). Lepidocrocite can be formed by mixing solutions of iron salts (Fe3+ or Fe2+) with an oxidant through precipitation or hydrolysis reactions (Cui et al. 2012).
Ten years outdoor exposure of steel in an urban and coastal tropical atmosphere
Published in Corrosion Engineering, Science and Technology, 2021
Juan A. Jaén, Kevin Guzmán, Josefina Iglesias, Griselda Caballero Manrique
In the early stages of atmospheric corrosion, lepidocrocite is predominant. As exposure time increases and the rust layer becomes thicker, the active lepidocrocite is partially transformed into goethite at the Tocumen test site, and to goethite and maghemite at the Sherman-Coastal test site. Cl− deposition is a major factor affecting the corrosion process, as the concentration of Cl− determines the structure of the rust layer formed on CS and the composition of corrosion products.