Hydrous Ferric Oxide

The redox properties of Fe II adsorbed onto a series of Fe III (oxyhydr)oxides (goethite, lepidocrocite, nano-sized ferric oxide hydrate (nano-FOH), and hydrous ferric oxide (HFO)) have been investigated by rest potential measurements at a platinum electrode, as a function of ...

Produced ceramic-lined steel pipe using the self-propagating high-temperature synthesis (SHS) method has found uses in many applications. A SHS-centrifugal machine was designed to produce a ceramic-lined steel pipe from ferric oxide and aluminum powder (thermite mixture) under high centrifugal acceleration. The obtained products are expected to be Al2O 3 ceramic in the innermost layer and a Fe layer in a region between the outer steel pipes. In the present work, specific regions of a pipe was particularly observed to investigate the stuck (dead) spaces at the pipe head because of its importance in further processes (joining, welding, etc.) which may affect the quality of the next operations. In this article, the product's composition, phase separation, microhardness, and surface finish were studied on three zones of the pipe.

http://link.springer.com/article/10.1007/s11837-012-0498-7

Volcanic rocks exposed at Q-prospect in the northern Chatree gold deposit, Phichit province, Thailand, appear to have erupted during Permo-Triassic period; they are geochemically composed of basalt porphyry, basaltic tuff and rhyolitic/rhyodacitic tuff. These host rocks are often cross cut by basaltic andesite dyke. Zr/TiO 2 versus SiO 2 diagram indicates that these volcanic hosts are significantly equivalent to sub-alkali basalt and rhyodacite–rhyolite. Based on trace element compositions, they appear to have derived from tholei-itic magma originated within mantle and partially involved by crustal material; on the other hand, basaltic andesite dyke may have originated from calc-alkaline magma at a shallower depth within crustal environment. A tectonic model of subduction-related island arc is therefore suggested for magma evolution that also led to gold deposit. Consequently, it fits very well with the regional tectonic of the country.

The prograde deserpentinized peridotites from the talc zone in the Happo-O'ne complex, central Japan, show differences in their field relation and mineral assemblage with the high-P retrograde peridotites of the other part of the complex. They show a mineral assemblage, olivine + talc + antigorite ± prograde tremolite ± chlorite, formed by thermal metamorphism around the granitic intrusion at T, 500–650 °C and P < 7 kbar. The olivine has numerous opaque inclusions and high Fo (91.5–96.5) relative to the ret-rograde olivine, reflecting its formation by deserpentinization. The prograde tremolite, which is low in Al 2 O 3 (<1.0 wt.%), Cr 2 O 3 (<0.35 wt.%), and Na 2 O (<0.6 wt.%) but high in Mg# (up to 0.98) and SiO 2 (up to 59.9 wt.%), is different in size, shape and chemistry from the retrograde tremolite. The prograde per-idotites display a U-shaped REE pattern (0.02–0.5 times PM), similar to diopside-zone retrograde meta-peridotites, possible protoliths. They are enriched in LILE (e.g., Cs, Pb, Sr, Rb) relative to HFSE (e.g., Ta, Hf, Zr, Nb), like their protoliths, because of their local re-equilibration with the fluid released during dehydration of the protoliths. They have high contents of REE and some trace elements (e.g., Cs, Th, U, Ta) relative to their protoliths because of an external-element addition from the granitic magma. In-situ analyses of peridotitic silicates confirmed that the prograde tremolite and talc display a spoon-shaped primitive mantle (PM)-normalized REE pattern (0.1–3 times PM) in which LREE are higher than HREE contents. The prograde tremolite is depleted in Al, Na, Cr, Sc, V, Ti, B, HREE and Li, but is enriched in Si, Cs, U, Th, HFSE (Hf, Zr, Nb, Ta), Rb and Ba relative to the retrograde tremolite; the immobile-element depletion in this tremolite is inherited from its source (antigorite + secondary diopside), whereas the depletion of mobile elements (e.g., Li, B, Na, Al) is ascribed to their mobility during the deserpentinization and/or the depleted character of the source of tremolite. The enrichment of HFSE and LILE in the prograde tremolite is related to an external addition of these elements from fluid/melt of the surrounding granitic magma and/or in situ equilibrium with LILE-bearing fluid released during dehydration of serpentinized retrograde metaperidotites and olivine-bearing serpentinites (protoliths). The prograde olivine is higher in REE and most trace-element contents than the retrograde one due to the external addition of these elements ; it is enriched in B, Co and Ni, but depleted in Li that was liberated during deserpentinization by prograde metamorphism. Crown

Acid-sulfate-chloride (pH3) geothermal springs in Yellowstone National Park (YNP) often contain Fe(II), As(III), and S(-II) at discharge, providing several electron donors for chemolithotrophic metabolism. The microbial populations inhabiting these environments are inextricably linked with geochemi- cal processes controlling the behavior of As and Fe. Consequently, the objectives of the current study were to (i) characterize Fe-rich microbial mats of an

Deinococcus radiodurans is an exceptionally radiation-resistant microorganism capable of surviving acute exposures to ionizing radiation doses of 15,000 Gy and previously described as having a strictly aerobic res- piratory metabolism. Under strict anaerobic conditions, D. radiodurans R1 reduced Fe(III)-nitrilotriacetic acid coupled to the oxidation of lactate to CO2 and acetate but was unable to link this process to growth. D. radio- durans reduced the humic acid analog anthraquinone-2,6-disulfonate (AQDS) to its dihydroquinone form, AH2DS, which subsequently transferred electrons to the Fe(III) oxides hydrous ferric oxide and goethite via a previously described electron shuttle mechanism. D. radiodurans reduced the solid-phase Fe(III) oxides in the presence of either 0.1 mM AQDS or leonardite humic acids (2 mg ml 21 ) but not in their absence. D. radio- durans also reduced U(VI) and Tc(VII) in the presence of AQDS. In contrast, Cr(VI) was directly reduced in anaerobic cultures wit...

Acid mine waters from the Iron Mountain Superfund Site, Shasta County, California, flow through Spring Creek Reservoir and into Keswick Reservoir on the Sacramento River. In Keswick Reservoir, the acid mine waters have neutralized on mixing with neutral-pH lake water, ...