Environmental photochemistry in hematite-oxalate system: Fe(III)-Oxalate complex photolysis and ROS generation

Xu, Tianyuan; Fang, Yumin; Tong, Tianyi; Xia, Yabei; Liu, Xiao; Zhang, Lizhi

doi:10.1016/j.apcatb.2020.119645

Cited by 44 publications

(14 citation statements)

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“…The photogenerated electrons in the conduction band of iron (hydr)oxides can be captured by Fe(III) to generate Fe(II). Alternatively, a number of studies also suggest that photolysis occurs on the surface hydroxyl groups of iron (hydr)oxides (e.g., Fe–OH) under light irradiation and electrons will transfer from surface hydroxyl group to Fe(III) which is known as a ligand to metal charge transfer (LMCT) process. − , …”

Section: Mechanisms Of Photoreductive Dissolution Of Iron (Hydr)oxidesmentioning

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%

“…Photoreductive dissolution of iron (hydr)oxides is an important pathway for driving the Fe cycle by solar irradiation, significantly affecting some important geochemical and environmental processes on Earth, primarily through the production of Fe 2+ , generation of ROS, and phase transformation of iron (hydr)oxides. The highly soluble Fe 2+ , generated by photoreductive dissolution of poorly soluble iron (hydr)oxides, plays a vital role in primary productivity, such as the photosynthesis of phytoplankton, and thus influences the ocean’s ability to absorb carbon dioxide from the atmosphere. − Light irradiation on iron (hydr)oxides can produce ROS through the photolysis of Fe–OH and the reduction of O 2 by photogenerated electrons. ,, The generated ROS (e.g., O 2 •– , H 2 O 2 , •OH) during the sunlight irradiation of iron (hydr)oxides are effective oxidants to NOM and organic contaminants, which can affect the global cycling of carbon and environmental quality. − Moreover, photoreductive dissolution of iron (hydr)oxides can decrease their stability and accelerate their dissolution and recrystallization, which may cause the transformation of some metastable iron (hydr)oxides to more stable minerals, e.g., Schwermannite to goethite . This process influences the composition of iron (hydr)oxides in the supergene environment.…”

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: Mechanisms Of Photoreductive Dissolution Of Iron (Hydr)oxidesmentioning

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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“…S18a–c†). 26,61 The adsorbed HC 2 O 4 − in the Fe(HC 2 O 4 )(OH) tended to transfer its proton to the nearest hydroxyl group on the HNP surface, forming an adsorbed H 2 O spontaneously (Fig. 4a).…”

Section: Resultsmentioning

confidence: 99%

“…25 For instance, the outer-sphere adsorption configuration of oxalate, which is formed via electrostatic and hydrogen bonding interactions with surface hydroxyl groups of iron (oxyhydr)oxides, disfavors iron dissolution. In contrast, the oxalate of inner-sphere adsorption configurations such as bidentate mononuclear (BM), monodentate mononuclear (MM), monodentate binuclear (MB), and bidentate binuclear (BB), 26 is formed by ligand-exchange reactions with surface hydroxyl groups. The main effect of oxalate promoted iron dissolution is attributed to the inner-sphere complexation of oxalate on the iron (oxyhydr)oxide surface, which is speculated to bring electrons into iron (oxyhydr)oxides, weakening the surface Fe–O bonds and leading to iron dissolution.…”

Section: Introductionmentioning

confidence: 99%

Oxalate promoted iron dissolution of hematite via proton coupled electron transfer

Zhan

Fang

Zhang

et al. 2022

Environ. Sci.: Nano

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Size‐Dependent Catalysis in Fenton‐like Chemistry: From Nanoparticles to Single Atoms

Guo,

Gao,

et al. 2024

Advanced Materials

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State‐of‐the‐art Fenton‐like reactions are crucial in advanced oxidation processes (AOPs) for water purification. This review explores the latest advancements in heterogeneous metal‐based catalysts within AOPs, covering nanoparticles (NPs), single‐atom catalysts (SACs), and ultra‐small atom clusters. A distinct connection between the physical properties of these catalysts, such as size, degree of unsaturation, electronic structure, and oxidation state, and their impacts on catalytic behavior and efficacy in Fenton‐like reactions. In‐depth comparative analysis of metal NPs and SACs was conducted focusing on how particle size variations and metal‐support interactions affect oxidation species and pathways. The review highlights the cutting‐edge characterization techniques and theoretical calculations, indispensable for deciphering the complex electronic and structural characteristics of active sites in downsized metal particles. Additionally, the review underscores innovative strategies for immobilizing these catalysts onto membrane surfaces, offering a solution to the inherent challenges of powdered catalysts. Recent advances in pilot‐scale or engineering applications of Fenton‐like based devices have also been summarized for the first time. The paper concludes by charting new research directions, emphasizing advanced catalyst design, precise identification of reactive oxygen species, and in‐depth mechanistic studies. These efforts aim to enhance the application potential of nanotechnology‐based AOPs in real‐world wastewater treatment.This article is protected by copyright. All rights reserved

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Environmental photochemistry in hematite-oxalate system: Fe(III)-Oxalate complex photolysis and ROS generation

Cited by 44 publications

References 54 publications

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

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

Oxalate promoted iron dissolution of hematite via proton coupled electron transfer

Size‐Dependent Catalysis in Fenton‐like Chemistry: From Nanoparticles to Single Atoms

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