How many nitrate-reducing bacteria have been detected in soils, freshwater,?

194,196,249,250Anaerobic nitrate-reducing Fe(II)-oxidizing bacteria have been detected in soils, freshwater, and marine habitats.

How many XMCDs have been used for the investigation of biogenic magnetite?

48 XMCD hasbeen utilized for the investigation of biogenic magnetite formed through the reduction of ferrihydrite by Fe(III)-reducing bacteria.280

What are the two main techniques to determine the redox potential of minerals?

Thereare two main classic techniques to determine the redox potential of minerals: non-invasive electrochemical methods (e.g. redox electrodes) and dissolving the mineralto quantify the ratio of oxidized and reduced species and using these to calculate atheoretical Nernstian potential.

What is the role of cation surfactants in the sorption of organic compounds?

For instance, the formation of mixed hemimicelles fromadsorption of cation surfactants - cetyltrimethylammonium bromide (CTAB) andcetylpyridinium chloride (CPC) - on magnetic nanoparticles, can enhance sorption of organic compounds by strong hydrophobic and electrostatic interactions.

What is the effect of organic matter on the formation of reactive Fe(II) surface sites?

The presence of associated organic matter(adsorbed or coprecipitated) is likely to influence heterogeneous electron transferprocesses and formation of reactive Fe(II) surface sites.

What is the effect of dissolved oxygen on the formation of a bilayer structure?

It was shown that the oxidation of Fe0 by dissolved oxygen was strongly enhanced by the presence of dissolved Fe(II)aqleading to the formation of a bilayer structure consisting of an inner layer ofmagnetite and an outer layer of -FeOOH.

What are the common methods used to estimate redox potentials of minerals?

Metallic redox electrodes commonly used to estimateredox potentials (such as Pt ring) usually do not provide reliable measurements in thecase of minerals due to a number of factors such as sorption of mineral to theelectrode, lack of redox equilibria between the analyte and the electrode and absence of active species in solution, among others.

What are the other factors which influence the magnetic properties of the mineral?

Other factors which also influence the magnetic properties of the mineral include the particle size67 and the inclusion of transition metals such as cobalt, zinc, and titanium.

What is the role of magnetite in the sorption of organic and inorganic pollutants?

For instance, magnetite commonly occurs in natural and engineered settings,99 and due to its reactive and highsurface area, it plays a significant role in the sorption of environmental pollutants(Table 9).

How did the size of the crystals increase with increasing current density?

The size of the crystals generally increased with increasingcurrent density or by decreasing the distance between the anode and the cathode.

What other methods have been developed to decrease iron leaching?

In addition, several otherstrategies have been developed to decrease iron leaching and to improve catalyst stability such as photo-Fenton,44,544,545 ultrasound assisted chemical oxidation,524,546 and UV-LED assisted oxidation.

What pathways were proposed to be relevant for magnetite formation in soils?

105,112 Both biotic101 and abiotic98 pathways were proposed to be relevantfor magnetite formation in soils (for details, see Section 4).

What is the description of the sorption properties of mixed-valent Fe minerals?

To best describe the sorption properties of mixed-valent Fe minerals, this section hasbeen subdivided into: (i) sorption of inorganic compounds including oxyanions, heavymetals and radionuclides; (ii) sorption of organic compounds including naturallyoccurring ligands and emerging contaminants.

Open AccessJournal Article10.1021/ACS.CHEMREV.7B00224

Magnetite and Green Rust: Synthesis, Properties, and Environmental Applications of Mixed-Valent Iron Minerals

Muhammad Usman, +9 more

- 21 Feb 2018

- Chemical Reviews

- Vol. 118, Iss: 7, pp 3251-3304

389

TL;DR: The aim is to present a detailed overview of the key aspects related to these mineral phases which can be used as an important resource for researchers working in a diverse range of fields dealing with mixed-valent iron minerals.

Abstract: Mixed-valent iron [Fe(II)-Fe(III)] minerals such as magnetite and green rust have received a significant amount of attention over recent decades, especially in the environmental sciences. These mineral phases are intrinsic and essential parts of biogeochemical cycling of metals and organic carbon and play an important role regarding the mobility, toxicity, and redox transformation of organic and inorganic pollutants. The formation pathways, mineral properties, and applications of magnetite and green rust are currently active areas of research in geochemistry, environmental mineralogy, geomicrobiology, material sciences, environmental engineering, and environmental remediation. These aspects ultimately dictate the reactivity of magnetite and green rust in the environment, which has important consequences for the application of these mineral phases, for example in remediation strategies. In this review we discuss the properties, occurrence, formation by biotic as well as abiotic pathways, characterization t...

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Most frequently asked questions

1. What are the different types of organic compounds used as electron donors?

The organic compounds usedas electron donor include simple fatty acids such as acetate and lactate but also morecomplex organic molecules such as aromatic compounds.

2. Why does synchrotron radiation lend itself towards this field?

Synchrotron radiation lends itself towards this field due toits element specificity combined with spatial resolution for analysing either bulk ornanoscale materials.

3. What type of magnetometer can be used to obtain a hysteresis?

Several types ofinstruments can be used to obtain a hysteresis loops including Alternating gradientforce magnetometer (AGFM), Vibrating Sample Magnetometer (VSM), orsuperconducting quantum interference device (SQUID) magnetometer.

4. What are the main issues that should be addressed before industrial applications?

Prior to industrial applications, injection mode, transport of particles in soil ormagnetite/soil mixing, eco-toxicity assessment, etc. should be addressed.

Table 7: A table of Mössbauer parameters for mixed-valent Fe minerals magnetite and green rust (GR). δ – isomer shift, ΔEQ – quadrupole splitting (ΔEQ=2ε) where ε is quadrupole shift, Bhf – hyperfine field, R.A. – relative abundance. The reference corresponding to each set of mineral parameters is also included.

Table 1: Overview of iron oxides. Reproduced with permission from Ref. 2. Copyright 2003 Wiley-VCH Verlag GmbH & Co. KGaA.

Figure 4: Soil containing fougèrite with bluish-green color. From Trolard et al.86 (2007, Figure No. 1). Reproduced with kind permission of The Clay Minerals Society, publisher of Clays and Clay Minerals.

Figure 11: Different morphologies of magnetite produced by MTB’s. Reproduced with permission from Ref. 294. Copyright 2016 Nature Publishing Group.

Figure 22: Fenton-like oxidation of TNT (0.11 mM) in the presence of six different iron minerals (2 g L−1) at pH 7: (■) hematite, (▴) ferrihydrite, (*) lepidocrocite, (♦) goethite, (○) magnetite, (▵) pyrite, (♢) green rust. H2O2 (3%, w/v). Reproduced with permission from Ref. 504. Copyright 2008 Elsevier.

Figure 16: (a) The Fe K-edge absorption spectrum. The inset figure shows the preedge feature, which when normalized can be used to calculate the centroid position and integrated pre-edge intensity. (b) Comparison between pre-edge intensity and centroid position (eV) for different oxidation and coordination states of Fe in various Fe minerals. Black circles are 1 humite; 2 rhodonite no. 1; 3 rhodonite no. 2; 4 dumortierite; 5 potassian kaersutite; 6 kaersutite; 7 vesuvianite no. 1; 8 vesuvianite no. 2; 9 franklinite, 10 magnetite no. 1 & no. 2; 11 labradorite; 12 maghemite. Both (a) and (b) are reproduced with permission from Ref. 369. Copyright 2001 Mineralogical Society of America.

Citations

Repository•10.6084/m9.figshare.26558099.v1

Additional file 1 of Effect of Ni2+, Zn2+, and Co2+ on green rust transformation to magnetite

Yee, Nathan

- 13 Aug 2024

Abstract: Additional file 1: Figure S1. Production of H2 gas. GR suspensions were heated at 85oC under anoxic conditions and headspace was analyzed using gas chromatography. Figure S2. Formation of a magnetic product. GR samples were heated at 85oC for 24 hours. The starting GR material is shown on the right and the magnetic product is shown on the left. Figure S3. Change in solution pH during GR transformation. Open symbols represent the room temperature control experiment and the closed symbol represent GR heated at 85oC. Figure S4. Replicate experiments of Ni incorporation during GR transformation to magnetite. Open symbols represent the room temperature control experiment, and the closed symbols represent 3 independent experiments of GR heated at 85oC in presence of 1 ppm Ni. Figure S5. 24 hour experiment of Ni incorporation during GR transformation to magnetite. Open symbols represent the room temperature control experiment and the closed symbols represent GR heated at 85oC. Figure S6. Changes in solution pH during GR transformation in the metal amended experiments. Open symbols represent the room temperature control experiment and the closed symbols represent GR samples heated at 85oC containing A) nickel, B) zinc, and C) cobalt.

...read moreread less

Journal Article•10.1021/acsearthspacechem.5c00199

Nanoscale Observation of Nickel(II) Sequestration by Green Rust Sulfate

Khondaker M. N. Alam, +3 more

- 28 Oct 2025

- ACS earth and space chemistry

Journal Article•10.1016/j.clay.2024.107627

Cronstedtite: H2 generation and new constraints on its formation conditions

Isabella Pignatelli, +4 more

- 01 Dec 2024

- Applied Clay Science

Book Chapter•10.1016/B978-0-12-820042-1.00026-2

Nanomaterials for soil remediation: Pollutant immobilization and opportunities for hybrid technologies

Diego Baragaño, +3 more

- 01 Jan 2021

TL;DR: The core-shell structure of zero-valent iron nanoparticles supports several immobilization mechanisms, as demonstrated in field-scale work, and thus making these particles the most widely used nanomaterials for remediation purposes as mentioned in this paper.

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Journal Article•10.1002/CPLU.202000600

Chemical Gardens as Electrochemical Systems: In Situ Characterization of Simulated Prebiotic Hydrothermal Vents by Impedance Spectroscopy.

Keith B. Chin, +3 more

- 01 Dec 2020

- ChemPlusChem

TL;DR: Continuous electrochemical impedance spectroscopy characterization on inorganic membranes representing prebiotic hydrothermal chimney vents in natural seafloor systems, by incorporating an electrode array into a chimney growth experiment confirms the elevated chemical reactivity in the chimney interior.

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References

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Aquatic Chemistry: Chemical Equilibria and Rates in Natural Waters

Werner Stumm, +1 more

- 01 Jan 1970

TL;DR: In this paper, the Solid-Water Interface Adsorption Dissolution of Minerals Nucleation and Crystal Growth Particle-Particle Interaction Colloids Coagulation and Filtration Regulation of the Chemical Composition of Natural Waters (Examples) Thermodynamic Data.

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Journal Article•10.1016/J.JHAZMAT.2007.01.006

Arsenic removal from water/wastewater using adsorbents—A critical review

Dinesh Mohan, +1 more

- 02 Apr 2007

- Journal of Hazardous Materials

TL;DR: Strong acids and bases seem to be the best desorbing agents to produce arsenic concentrates, and some commercial adsorbents which include resins, gels, silica, treated silica tested for arsenic removal come out to be superior.

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LXXIII.—Oxidation of tartaric acid in presence of iron

H. J. H. Fenton

- 01 Jan 1894

- Journal of The Chemical Society, Transac...

Journal Article•10.1016/0016-7037(64)90129-2

Abundance of chemical elements in the continental crust: a new table

Stuart Ross Taylor

- 01 Aug 1964

- Geochimica et Cosmochimica Acta

TL;DR: In this article, a table of element abundances in the continental crust, calculated on the basis of a 1:1 mixture of granite and basalt abundances, is presented.

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Journal Article•10.1016/0031-9201(77)90108-X

Hysteresis properties of titanomagnetites: Grain-size and compositional dependence

R. Day, +2 more

- 01 Jan 1977

- Physics of the Earth and Planetary Inter...

TL;DR: In this article, the grain-size dependence of parameters with coercive force as high as 2,000 Oe in x = 0.6 titanomagnetite was found.

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Magnetite and Green Rust: Synthesis, Properties, and Environmental Applications of Mixed-Valent Iron Minerals

Chat with Paper

AI Agents for this Paper

Most frequently asked questions

1. What are the different types of organic compounds used as electron donors?

2. Why does synchrotron radiation lend itself towards this field?

3. What type of magnetometer can be used to obtain a hysteresis?

4. What are the main issues that should be addressed before industrial applications?

5. How many nitrate-reducing bacteria have been detected in soils, freshwater,?

6. How many XMCDs have been used for the investigation of biogenic magnetite?

7. What are the two main techniques to determine the redox potential of minerals?

8. What is the role of cation surfactants in the sorption of organic compounds?

9. What is the effect of organic matter on the formation of reactive Fe(II) surface sites?

10. What is the effect of dissolved oxygen on the formation of a bilayer structure?

11. What are the common methods used to estimate redox potentials of minerals?

12. What are the other factors which influence the magnetic properties of the mineral?

13. What is the role of magnetite in the sorption of organic and inorganic pollutants?

14. How did the size of the crystals increase with increasing current density?

15. What other methods have been developed to decrease iron leaching?

16. What pathways were proposed to be relevant for magnetite formation in soils?

17. What is the description of the sorption properties of mixed-valent Fe minerals?

Figures

Citations

Additional file 1 of Effect of Ni2+, Zn2+, and Co2+ on green rust transformation to magnetite

Nanoscale Observation of Nickel(II) Sequestration by Green Rust Sulfate

Cronstedtite: H2 generation and new constraints on its formation conditions

Nanomaterials for soil remediation: Pollutant immobilization and opportunities for hybrid technologies

Chemical Gardens as Electrochemical Systems: In Situ Characterization of Simulated Prebiotic Hydrothermal Vents by Impedance Spectroscopy.

References

Aquatic Chemistry: Chemical Equilibria and Rates in Natural Waters

Arsenic removal from water/wastewater using adsorbents—A critical review

LXXIII.—Oxidation of tartaric acid in presence of iron

Abundance of chemical elements in the continental crust: a new table

Hysteresis properties of titanomagnetites: Grain-size and compositional dependence

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