Biogenic Mineral Formation by Iron Reducing Bacteria

2001 ◽  
Vol 7 (S2) ◽  
pp. 756-757
Author(s):  
Alice C. Dohnalkova ◽  
Yuri A. Gorby ◽  
Jeff McLean ◽  
Jim K. Fredrickson ◽  
David W. Kennedy
Keyword(s):  
Ferrous Iron ◽  
Ferric Iron ◽  
Metal Reduction ◽  
Mineral Formation ◽  
X Ray Diffraction ◽  
X Ray ◽  
Iron Reducing Bacteria ◽  
Reducing Bacteria ◽  
Insoluble Mineral

Dissimilatory iron reducing bacteria have been extensively studied for their ability to reduce ferric iron Fe(III) to ferrous iron Fe(II), as well as several multivalent heavy metals and radionuclides as a mode of energy-yielding respiration. Shewanella putrefaciens strain CN32 was used to investigate the mechanism of biogenic metal reduction in systems simulating conditions of natural anaerobic iron reducing environments in the subsurface contaminated with U and Tc as a possible strategy for bioremediation of soils containing these contaminants. As previously reviewed, U(VI) is soluble in most groundwaters, while U(VI) generally precipitates as the insoluble mineral uraninite. Formation of bioreduced minerals can lead to immobilization of these contaminants in the subsurface, which might be a very useful strategy for in situ bioremediation.To determine the metal reduction and the formation of biogenic Fe(II), U(IV) and Tc(IV) minerals, experiments with CN32 exposed to well-defined aqueous solutions were conducted. Metal reduction was measured with time, and the resulting solids were analyzed by X-ray diffraction, scanning electron microscopy (SEM) and energydispersive X-ray spectroscopy (EDS).

Reaction pathways of iron-sulfide mineral formation: an in situ X-ray diffraction study

2018 ◽  
Vol 30 (1) ◽  
pp. 77-84 ◽  
Author(s):  
Min-Yu Lin ◽  
Yen-Hua Chen ◽  
Jey-Jau Lee ◽  
Hwo-Shuenn Sheu
Keyword(s):  
Diffraction Study ◽  
Iron Sulfide ◽  
Sulfide Mineral ◽  
Reaction Pathways ◽  
Mineral Formation ◽  
X Ray Diffraction ◽  
X Ray

scholarly journals Effects of Fe(III) Oxide Mineralogy and Phosphate on Fe(II) Secondary Mineral Formation during Microbial Iron Reduction

Minerals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 149
Author(s):  
Edward J. O’Loughlin ◽  
Maxim I. Boyanov ◽  
Christopher A. Gorski ◽  
Michelle M. Scherer ◽  
Kenneth M. Kemner
Keyword(s):  
Iron Reduction ◽  
Phosphate Concentration ◽  
Green Rust ◽  
Mineral Formation ◽  
Secondary Mineral ◽  
X Ray Diffraction ◽  
Secondary Minerals ◽  
Iron Reducing Bacteria ◽  
Secondary Mineral Formation ◽  
Reducing Bacteria

The bioreduction of Fe(III) oxides by dissimilatory iron-reducing bacteria may result in the formation of a suite of Fe(II)-bearing secondary minerals, including magnetite (a mixed Fe(II)/Fe(III) oxide), siderite (Fe(II) carbonate), vivianite (Fe(II) phosphate), chukanovite (ferrous hydroxy carbonate), and green rusts (mixed Fe(II)/Fe(III) hydroxides). In an effort to better understand the factors controlling the formation of specific Fe(II)-bearing secondary minerals, we examined the effects of Fe(III) oxide mineralogy, phosphate concentration, and the availability of an electron shuttle (9,10-anthraquinone-2,6-disulfonate, AQDS) on the bioreduction of a series of Fe(III) oxides (akaganeite, feroxyhyte, ferric green rust, ferrihydrite, goethite, hematite, and lepidocrocite) by Shewanella putrefaciens CN32, and the resulting formation of secondary minerals, as determined by X-ray diffraction, Mössbauer spectroscopy, and scanning electron microscopy. The overall extent of Fe(II) production was highly dependent on the type of Fe(III) oxide provided. With the exception of hematite, AQDS enhanced the rate of Fe(II) production; however, the presence of AQDS did not always lead to an increase in the overall extent of Fe(II) production and did not affect the types of Fe(II)-bearing secondary minerals that formed. The effects of the presence of phosphate on the rate and extent of Fe(II) production were variable among the Fe(III) oxides, but in general, the highest loadings of phosphate resulted in decreased rates of Fe(II) production, but ultimately higher levels of Fe(II) than in the absence of phosphate. In addition, phosphate concentration had a pronounced effect on the types of secondary minerals that formed; magnetite and chukanovite formed at phosphate concentrations of ≤1 mM (ferrihydrite), <~100 µM (lepidocrocite), 500 µM (feroxyhyte and ferric green rust), while green rust, or green rust and vivianite, formed at phosphate concentrations of 10 mM (ferrihydrite), ≥100 µM (lepidocrocite), and 5 mM (feroxyhyte and ferric green rust). These results further demonstrate that the bioreduction of Fe(III) oxides, and accompanying Fe(II)-bearing secondary mineral formation, is controlled by a complex interplay of mineralogical, geochemical, and microbiological factors.

The Use of Advanced Analytical Techniques for Characterization of the Chemical, Physical, and Crystallographic Nature of a Surface

1973 ◽  
Vol 31 ◽  
pp. 132-133 ◽  
Author(s):  
R. E. Herfert
Keyword(s):  
Surface Characterization ◽  
Analytical Techniques ◽  
X Ray Diffraction ◽  
Depth Of Penetration ◽  
X Ray ◽  
The Past ◽  
Transmission Electron ◽  
Scanning Electron

Studies of the nature of a surface, either metallic or nonmetallic, in the past, have been limited to the instrumentation available for these measurements. In the past, optical microscopy, replica transmission electron microscopy, electron or X-ray diffraction and optical or X-ray spectroscopy have provided the means of surface characterization. Actually, some of these techniques are not purely surface; the depth of penetration may be a few thousands of an inch. Within the last five years, instrumentation has been made available which now makes it practical for use to study the outer few 100A of layers and characterize it completely from a chemical, physical, and crystallographic standpoint. The scanning electron microscope (SEM) provides a means of viewing the surface of a material in situ to magnifications as high as 250,000X.

In-situ Investigation of Bainite Formation with fast X-Ray Diffraction (iXRD)

2017 ◽  
Vol 72 (6) ◽  
pp. 355-364
Author(s):  
A. Kopp ◽  
T. Bernthaler ◽  
D. Schmid ◽  
G. Ketzer-Raichle ◽  
G. Schneider
Keyword(s):  
X Ray Diffraction ◽  
X Ray ◽  
In Situ Investigation

Texture Evolution Under Fast Heating and Cooling Rates of Zirconium Alloys Studied In-Situ by Synchrotron X-Ray Diffraction

2020 ◽  
Author(s):  
Chi-Toan Nguyen ◽  
Alistair Garner ◽  
Javier Romero ◽  
Antoine Ambard ◽  
Michael Preuss ◽  
...  
Keyword(s):  
Texture Evolution ◽  
Zirconium Alloys ◽  
X Ray Diffraction ◽  
Fast Heating ◽  
Cooling Rates ◽  
X Ray ◽  
Heating And Cooling

STRUCTURAL EVOLUTION OF EXCEPTIONALLY IRON-DEFICIENT HEMATITE NANOCRYSTALS AS OBSERVED BY IN SITU SYNCHROTRON X-RAY DIFFRACTION

2019 ◽  
Author(s):  
Si Athena Chen ◽  
◽  
Peter Heaney ◽  
Jeffrey E. Post ◽  
Peter J. Eng ◽  
...  
Keyword(s):  
Structural Evolution ◽  
X Ray Diffraction ◽  
X Ray ◽  
Iron Deficient

In situ X-ray diffraction techniques as a powerful tool to study battery electrode materials

2002 ◽  
Vol 47 (19) ◽  
pp. 3137-3149 ◽  
Author(s):  
M. Morcrette ◽  
Y. Chabre ◽  
G. Vaughan ◽  
G. Amatucci ◽  
J.-B. Leriche ◽  
...  
Keyword(s):  
Electrode Materials ◽  
X Ray Diffraction ◽  
X Ray ◽  
Battery Electrode

scholarly journals In-Situ Synchrotron X-ray Diffraction Investigation of Microstructural Evolutions During Low-Pressure Carburizing

2021 ◽  
Author(s):  
Ogün Baris Tapar ◽  
Jérémy Epp ◽  
Matthias Steinbacher ◽  
Jens Gibmeier
Keyword(s):  
Carbon Content ◽  
Carbon Diffusion ◽  
Low Pressure ◽  
Carbon Accumulation ◽  
Experimental Chamber ◽  
Carbide Formation ◽  
X Ray Diffraction ◽  
X Ray ◽  
Carbon Supply

AbstractAn experimental heat treatment chamber and control system were developed to perform in-situ X-ray diffraction experiments during low-pressure carburizing (LPC) processes. Results from the experimental chamber and industrial furnace were compared, and it was proven that the built system is reliable for LPC experiments. In-situ X-ray diffraction investigations during LPC treatment were conducted at the German Electron Synchrotron Facility in Hamburg Germany. During the boost steps, carbon accumulation and carbide formation was observed at the surface. These accumulation and carbide formation decelerated the further carbon diffusion from atmosphere to the sample. In the early minutes of the diffusion steps, it is observed that cementite content continue to increase although there is no presence of gas. This effect is attributed to the high carbon accumulation at the surface during boost steps which acts as a carbon supply. During quenching, martensite at higher temperature had a lower c/a ratio than later formed ones. This difference is credited to the early transformation of austenite regions having lower carbon content. Also, it was noticed that the final carbon content dissolved in martensite reduced compared to carbon in austenite before quenching. This reduction was attributed to the auto-tempering effect.

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