A critical review of abiotic and microbially-mediated chemical reduction rates of Fe(III) (oxyhydr)oxides using a reactivity model

Xiu, Wei; Yuan, Wenjie; Polya, David A.; Guo, Huaming; Lloyd, Jonathan R.

doi:10.1016/j.apgeochem.2021.104895

Cited by 14 publications

(7 citation statements)

References 156 publications

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“…In a supergene environment, iron (hydr)oxides always coexist with various types of chemicals, which significantly influence the photoreductive dissolution of iron (hydr)oxides. ,,,, Many types of NOM can serve as electron donors and Fe(II) stabilizers, which then reduce Fe(III) to Fe(II) on iron (hydr)oxides and slow down the reoxidation of Fe(II), respectively, accelerating the photoreductive dissolution of iron (hydr)oxides. ,− In addition to NOM, inorganic anions influence the photoreductive dissolution of iron (hydr)oxides by act acting as hole scavengers, ligands, and/or oxidizing agents.…”

Section: The Factors Affecting Photoreductive Dissolution Of Iron (Hy...mentioning

confidence: 99%

“…Most iron (hydr)oxides are thermodynamically stable, but their structural Fe can be mobilized through biotic and abiotic reductive dissolution. , Biotic reduction of Fe(III) present in iron (hydr)oxides generally takes place in anaerobic soils and sediments, − where microorganisms can reduce Fe(III) through intracellular metabolism − or extracellular electron transfer. ,− Abiotic reduction of Fe(III) within iron (hydr)oxides mainly includes chemical reduction and photoreduction. Chemical reduction needs reductants, such as sulfides and natural organic matters (NOM), to directly donate electrons to iron (hydr)oxides. ,− During photoreduction processes, photoelectrons can be generated in iron (hydr)oxides to reduce Fe(III), because of their semiconductor characteristics and/or photolysis characteristics. − In additon, sunlight can also accelerate electron transfer from ligands to iron (hydr)oxides for Fe(III) reduction. − Sunlight can easily penetrate through air, and has a penetration depth from a few meters to hundreds of meters in water and from hundreds of micrometers to several millimeters in sediments. − In this term, the photoreduction of iron (hydr)oxides can occur in air, water, and sediments.…”

Section: Introductionmentioning

confidence: 99%

“…5,13−18 Most iron (hydr)oxides are thermodynamically stable, but their structural Fe can be mobilized through biotic and abiotic reductive dissolution. 19,20 Biotic reduction of Fe(III) present in iron (hydr)oxides generally takes place in anaerobic soils and sediments, 21−24 where microorganisms can reduce Fe(III) through intracellular metabolism 25−27 or extracellular electron transfer. 12,28−30 Abiotic reduction of Fe(III) within iron (hydr)oxides mainly includes chemical reduction and photoreduction.…”

Section: Introductionmentioning

confidence: 99%

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Photoreductive Dissolution of Iron (Hydr)oxides and Its Geochemical Significance

Liu

Zhu

et al. 2022

ACS Earth Space Chem.

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Iron (hydr)oxides are the most abundant metal oxides, which are widespread on Earth’s surface in the major form of micro/nanoparticles. Dissolution of iron (hydr)oxides significantly controls their compositions on Earth’s surface and is a critical step for the global Fe cycling. Photoreductive dissolution of iron (hydr)oxides is recognized as one of the most important process for generating Fe2+ in surface water and is also a common pathway for transforming solar energy into chemical energy. This review article dissects the main characteristics of photoreductive dissolution of iron (hydr)oxides and discusses its geochemical and environmental significance. We categorize the mechanisms for photoreduction of iron (hydr)oxides into three types: reduction by intrinsic photogenerated electrons, reduction by ligand to metal electron transfer (LMCT), and reduction by direct injection of exogenous photoelectrons. The efficiency of photoreductive dissolution is constrained by both the structure of iron (hydr)oxides (e.g., crystal structure and particle size) and environmental conditions (e.g., light, pH, and concurrent chemicals). Therefore, different iron (hydr)oxides may exhibit quite distinctive photoreductive dissolution characteristics because of their unique crystal structures and physicochemical properties. Iron (hydr)oxides with low crystallinity (e.g., ferrihydrite, lepidocrocite) are subject to direct photoreductive dissolution, while those with high crystallinity (e.g., goethite, hematite) generally need ligands to proceed with photoreductive dissolution. The photoreductive dissolution of iron (hydr)oxides is involved in many important geochemical and environmental processes, such as the Fe availability to primary producers, the generation of reactive oxygen species, the transportation and fate of contaminants, and the phase transformation of iron (hydr)oxides. Given the ubiquitous occurrence of photoreductive dissolution of iron (hydr)oxides, this review will advance our understanding of the role of this process in Earth’s surface environments.

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Section: The Factors Affecting Photoreductive Dissolution Of Iron (Hy...mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Photoreductive Dissolution of Iron (Hydr)oxides and Its Geochemical Significance

Liu

Zhu

et al. 2022

ACS Earth Space Chem.

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“…1 The two most common Fe redox states exist as: (1) Fe(II), the reduced form that is usually soluble and bioavailable, and (2) Fe(III), the oxidized form that is poorly soluble at circumneutral pH and easily transformed to Fe(III) (hydr)oxide solids. 1,2 Ferrihydrite, a metastable and poorly crystalline mineral, is the common iron precipitate that appears first during the Fe(III) hydrolysis process. 3,4 It is also the necessary precursor to other crystalline Fe oxyhydroxides with more thermodynamic stability, such as goethite (α-FeOOH), lepidocrocite (γ-FeOOH), and hematite (α-Fe 2 O 3 ).…”

Section: ■ Introductionmentioning

confidence: 99%

“…Iron is the fourth most abundant element in the Earth’s crust and widely distributed in natural environments exposed to solar irradiation . The two most common Fe redox states exist as: (1) Fe(II), the reduced form that is usually soluble and bioavailable, and (2) Fe(III), the oxidized form that is poorly soluble at circumneutral pH and easily transformed to Fe(III) (hydr)oxide solids. , Ferrihydrite, a metastable and poorly crystalline mineral, is the common iron precipitate that appears first during the Fe(III) hydrolysis process. , It is also the necessary precursor to other crystalline Fe oxyhydroxides with more thermodynamic stability, such as goethite (α-FeOOH), lepidocrocite (γ-FeOOH), and hematite (α-Fe 2 O 3 ). − The dynamic transformation of ferrihydrite to other mineral phases affect the migration, conversion, and bioavailability of many heavy metals (such as Pb, Cr, and U) and organic contaminants in various natural settings including the acid mine drainage (AMD)-impacted aquatic systems. − …”

Section: Introductionmentioning

confidence: 99%

Sunlight-Induced Interfacial Electron Transfer of Ferrihydrite under Oxic Conditions: Mineral Transformation and Redox Active Species Production

Shu

Pan

Wang

et al. 2022

Environ. Sci. Technol.

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Fe(II)-catalyzed ferrihydrite transformation under anoxic conditions has been intensively studied, while such mechanisms are insufficient to be applied in oxic environments with depleted Fe(II). Here, we investigated expanded pathways of sunlight-driven ferrihydrite transformation in the presence of dissolved oxygen, without initial addition of dissolved Fe(II). We found that sunlight significantly facilitated the transformation of ferrihydrite to goethite compared to that under dark conditions. Redox active species (hole–electron pairs, reactive radicals, and Fe(II)) were produced from the ferrihydrite interface via the photoinduced electron transfer processes. Experiments with systematically varied wet chemistry conditions probed the relative contributions of three pathways for the production of hydroxyl radicals: (1) oxidation of water (5.0%); (2) reduction of dissolved oxygen (40.9%); and (3) photolysis of Fe(III)-hydroxyl complexes (54.1%). Results also showed superoxide radicals as the main oxidant for Fe(II) reoxidation under acidic conditions, thus promoting the ferrihydrite transformation. The presence of inorganic ions (chloride, sulfate, and nitrate) did not only affect the hydrolysis and precipitation of Fe(III) but also the generation of radicals via photoinduced charge transfer reactions. The involvement of redox active species and the accompanying mineral transformations would exert a profound effect on the fate of multivalent elements and organic contaminants in aquatic environments.

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Water–Rock Interactions

Guo¹,

Gao²,

Xing³

2023

Medical Geology

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A critical review of abiotic and microbially-mediated chemical reduction rates of Fe(III) (oxyhydr)oxides using a reactivity model

Cited by 14 publications

References 156 publications

Photoreductive Dissolution of Iron (Hydr)oxides and Its Geochemical Significance

Photoreductive Dissolution of Iron (Hydr)oxides and Its Geochemical Significance

Sunlight-Induced Interfacial Electron Transfer of Ferrihydrite under Oxic Conditions: Mineral Transformation and Redox Active Species Production

Water–Rock Interactions

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