Magnetite and Green Rust: Synthesis, Properties, and Environmental Applications of Mixed-Valent Iron Minerals Muhammad Usman, J M Byrne, A Chaudhary, S Orsetti, Khalil Hanna, C Ruby, A Kappler, S B Haderlein To cite this version: Muhammad Usman, J M Byrne, A Chaudhary, S Orsetti, Khalil Hanna, et al.. Magnetite and Green Rust: Synthesis, Properties, and Environmental Applications of Mixed-Valent Iron Minerals. Chemical Reviews, American Chemical Society, 2018, 118 (7), pp.3251-3304. 10.1021/acs.chemrev.7b00224. hal-01771511 HAL Id: hal-01771511 https://hal-univ-rennes1.archives-ouvertes.fr/hal-01771511 Submitted on 29 May 2018 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. Magnetite and green rust: synthesis, properties and environmental applications of mixed-valent iron minerals M. Usman1, 2*, J. M. Byrne3, A. Chaudhary1,4, S. Orsetti1, K. Hanna5, C. Ruby6, A. Kappler3, S. B. Haderlein1 1 Environmental Mineralogy, Center for Applied Geosciences, University of Tübingen, 72074 Tübingen, Germany 2 Institute of Soil and Environmental Sciences, University of Agriculture, Faisalabad– 38040, Pakistan 3 Geomicrobiology, Center for Applied Geosciences, University of Tübingen, 72074 Tübingen, Germany 4 Department of Environmental Science and Engineering, Government College University Faisalabad, Pakistan 5 Univ Rennes, École Nationale Supérieure de Chimie de Rennes, CNRS, ISCR – UMR6226, F-35000 Rennes, France 6 Laboratoire de Chimie Physique et Microbiologie pour l’Environnement, UMR 7564 CNRS-Université de Lorraine, 54600 Villers-Lès-Nancy, France * Corresponding author: M. Usman manuscript Research Fellow (Alexander von Humboldt-Foundation) Environmental Mineralogy, Center for Applied Geosciences, University of Tübingen Hölderlinstr. 12, 72074 Tübingen, Germany Email: [email protected] or: [email protected] Phone No.: +49 70 71 29 78 924 Fax: +49 70 71 29 50 59 Accepted 1 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 techniques, and environmental applications of magnetite and green rust in the environment. 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. manuscript Accepted 2 Contents 1. Introduction 4 2. Properties of mixed-valent iron minerals 7 2.1. Structural properties 7 2.2. Fe(II): Fe(III) ratio 12 2.3. Redox Potential 15 2.4. Magnetic properties 18 2.5. Thermodynamic properties 22 3. Occurrence of mixed-valent iron minerals in the environment 23 3.1. Natural environments 23 3.2. Corrosion products in engineered systems 26 4. Synthesis of mixed-valent iron minerals 28 4.1. Abiotic synthesis of mixed-valent iron minerals 28 4.1.1. Co-precipitation of dissolved Fe(II) and Fe(III) species 28 4.1.2. Partial oxidation of hydroxylated dissolved Fe(II) and (Fe(II)aq, Fe(OH)2) mixture 31 4.1.3. Chemical or electrochemical oxidation of zero-valent iron 33 4.1.4. Interaction of Fe(II) with Fe(III) (oxyhydr)oxides 37 4.2. Synthesis of mixed-valent iron minerals by microbial activity 45 4.2.1. Synthesis by bacterial Fe(III) reduction 45 4.2.2. Synthesis of mixed-valent iron minerals by bacterial Fe(II) oxidation 50 4.2.3. Magnetotactic bacteria 55 5. Identification and quantification techniques 60 5.1. X–ray diffraction 60 5.2. Mössbauer spectroscopy 64 5.3. Vibrational spectroscopy manuscript70 5.4. Synchrotron X-ray absorption 73 5.5. Transmission electron microscopy and scanning electron microscopy 78 5.6. Magnetic measurements 81 6. Application of mixed-valent iron minerals for environmental remediation 86 6.1. Sorption of contaminants 86 6.1.1. Inorganic compounds 88 6.1.2. Organic compounds 91 6.2. Reductive transformation of inorganic and organic contaminants 99 6.3. Use of mixed-valent iron minerals to promote advanced oxidation processes 111 7. Conclusions and outlook 126 Acknowledgments 128 Biography 129 References 131 Table of content graphic 167 Accepted 3 1. Introduction Iron (Fe) is the fourth most abundant element in the earth crust with an average mass concentration of 5.6% and is the second most abundant metal after aluminum.1 Fe exists in almost all aquatic and terrestrial environments. Fe is commonly found to form together with O, and/or OH either oxides, hydroxides or oxide-hydroxides which are collectively referred to as ‘iron oxides’ in this review article. There are 16 known iron oxides (Table 1) having different crystal structure, chemical composition and, Fe valence state.2 Iron oxides are categorized into three different groups based on Fe oxidation state including: (i) ferric oxides bearing only trivalent Fe(III), including ferrihydrite, goethite, hematite, lepidocrocite etc., (ii) very rare ferrous oxides containing exclusively divalent Fe(II), with only examples of Fe(II)O and Fe(II)(OH)2, and (iii) mixed-valent iron oxides containing both Fe(III) and Fe(II) in their structure which include magnetite and green rust (GR). Iron predominantly exists as Fe(III) oxides especially near the surfacemanuscript of Earth’s crust due to the presence of oxygen. However, under appropriate redox conditions in aquatic or terrestrial environments, Fe(III) oxides can serve as electron acceptors for microbial respiration or react with Fe(II) or other reductants to form mixed-valent Fe minerals such as magnetite and GR which are the focus of this review. Magnetite [Fe(II)Fe(III)2O4], a black ferromagnetic mineral, is a member of the spinel group of minerals while GRs are layered double hydroxides.3 GRs appear in intense bluish green colors. AcceptedStructurally, GRs contain both Fe(II) and Fe(III) cations in brucite-like layers along with intercalated anions. Most common types of GRs are hydroxysulfate GR 2– 2– – [GR(SO4 )], hydroxycarbonate GR [GR(CO3 )], and hydroxychloride GR [GR(Cl )] 2– 2– according to the type of intercalated anions, i.e., sulfate (SO4 ), carbonate (CO3 ), or 4 chloride (Cl–), respectively. A detailed description of structural properties of both magnetite and GR is presented in the section 2 of this review. Table 1: Overview of iron oxides. Reproduced with permission from Ref. 2. Copyright 2003 Wiley-VCH Verlag GmbH & Co. KGaA. Oxide-hydroxides and hydroxides Oxides Goethite α-FeOOH Hematite α-Fe2O3 Lepidocrocite γ-FeOOH Magnetite Fe3O4 Akaganéite β-FeOOH Maghemite γ-Fe2O3 [Fe(II)Fe(III)2O4) Schwertmannite Fe16O16(OH)y(SO4)z•nH2O β-Fe2O3 δ-FeOOH -Fe2O3 Feroxyhyte δ'-FeOOH Wüstite FeO High pressure FeOOH Ferrihydrite Fe5HO8• 4H2O Bernalite Fe(OH)3 Fe(OH)2 – – – 2– Green rusts Fe(III)xFe(II)y (OH)3x+2y–z(A )z ; A = Cl ; 1/2 SO4 Mixed-valent Fe minerals are amongst the most reactive iron compounds due to their role in biogeochemical cycling of trace elements,manuscript their ability to affect the mobility, redox transformation, and toxicity of various organic and inorganic pollutants, and their use in various environmental remediation strategies. A large amount of research concerning mixed-valent iron oxides has been carried out in recent decades, but despite the immense amount of collected research data, no comprehensive review of this topic has been published. Our review article is intended to compile the research data related to all aspects of mixed-valent Fe minerals (magnetite and GR) including their characteristics, presence, formation, and role in the environment. AcceptedOnly narrow aspects of this wide research field were reviewed so far. For example, a very recent review article by Su C.4 describes the environmental applications of engineered magnetite nanoparticles and its hybrid composites. Munoz et al.,5 in 2015, reviewed various methods to form magnetite-based catalysts followed by their 5 efficiency to improve Fenton oxidation for treatment of industrial wastewater. In 2013, Tang et al.6 presented a comprehensive review of various factors to be considered for sustainable environmental application of magnetic nano-materials like magnetite, maghemite, and zero-valent iron (Fe0). Another review article in 2012 discussed the catalytic role of various