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F. Marc Michel - One of the best experts on this subject based on the ideXlab platform.
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Properties of impurity-bearing Ferrihydrite II: Insights into the surface structure and composition of pure, Al- and Si-bearing Ferrihydrite from Zn(II) sorption experiments and Zn K-edge X-ray absorption spectroscopy
Geochimica et Cosmochimica Acta, 2013Co-Authors: A. Cristina Cismasu, Clement Levard, F. Marc MichelAbstract:Abstract Naturally occurring Ferrihydrite often contains impurities such as Al and Si, which can impact its chemical reactivity with respect to metal(loid) adsorption and (in)organic or microbially induced reductive dissolution. However, the surface composition of impure Ferrihydrites is not well constrained, and this hinders our understanding of the factors controlling the surface reactivity of these nanophases. In this study, we conducted Zn(II) adsorption experiments combined with Zn K-edge X-ray absorption spectroscopy measurements on pure Ferrihydrite (Fh) and Al- or Si-bearing Ferrihydrites containing 10 and 20 mol% Al or Si (referred to as 10AlFh, 20AlFh and 10SiFh, 20SiFh) to evaluate Zn(II) uptake in relation to Zn(II) speciation at their surfaces. Overall, Zn(II) uptake at the surface of AlFh is similar to that of pure Fh, and based on Zn K-edge \EXAFS\ data, Zn(II) speciation at the surface of Fh and AlFh also appears similar. Binuclear bidentate IVZn–VIFe complexes (at ∼3.46 Å (2C[1]) and ∼3.25 Å (2C[2])) were identified at low Zn(II) surface coverages from Zn K-edge \EXAFS\ fits. With increasing Zn(II) surface coverage, the number of second-neighbor Fe ions decreased, which was interpreted as indicating the formation of \IVZn\ polymers at the Ferrihydrite surface, and a deviation from Langmuir uptake behavior. Zn(II) uptake at the surface of SiFh samples was more significant than at Fh and AlFh surfaces, and was attributed to the formation of outer-sphere complexes (on average 24% of sorbed Zn). Although similar Zn–Fe/Zn distances were obtained for the Zn-sorbed SiFh samples, the number of Fe second neighbors was lower in comparison with Fh. The decrease in second-neighbor Fe is most pronounced for sample 20SiFh, suggesting that the amount of reactive surface Fe sites diminishes with increasing Si content. Although our \EXAFS\ results shown here do not provide evidence for the existence of Zn–Al or Zn–Si complexes, their presence is not excluded for Zn-sorbed AlFh or SiFh. The results of this study indicate that Zn(II) interaction with Fh is influenced by the type of impurities associated with this nanomineral, particularly in the case of Si-bearing Fh, and this may have implications for our understanding of metal(loid) mobility in natural systems.
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Reactivity of ferritin and the structure of ferritin-derived Ferrihydrite
Biochimica et biophysica acta, 2010Co-Authors: F. Marc Michel, John B. Parise, Hazel-ann Hosein, Douglas B. Hausner, Sudeep Debnath, Daniel R. StronginAbstract:Abstract Background In nature or in the laboratory, the roughly spherical interior of the ferritin protein is well suited for the formation and storage of a variety of nanosized metal oxy-hydroxide compounds which hold promise for a range of applications. However, the linkages between ferritin reactivity and the structure and physicochemical properties of the nanoparticle core, either native or reconstituted, remain only partly understood. Scope of review Here we review studies, including those from our laboratory, which have investigated the structure of ferritin-derived Ferrihydrite and reactivity of ferritin, both native and reconstituted. Selected proposed structure models for Ferrihydrite are discussed along with the structural and genetic relationships that exist among several different forms of Ferrihydrite. With regard to reactivity, the review will emphasize studies that have investigated the (photo)reactivity of ferritin and ferritin-derived materials with environmentally relevant gaseous and aqueous species. Major conclusions The inorganic core formed from apoferritin reconstituted with varied amounts of Fe has the same structural topology as the inorganically derived Ferrihydrite that is an important component of many environmental and soil systems. Reactivity of ferritin toward aqueous species resulting from the photoexcitation of the inorganic core of the protein shows promise for driving redox reactions relevant to environmental chemistry. General significance Ferritin-derived Ferrihydrite is effectively maintained in a relatively unaggregated state, which improves reactivity and opens the possibility of future applications in environmental remediation. Advances in our understanding of the structure, composition, and disorder in synthetic, inorganically derived Ferrihydrite are shedding new light on the reactivity and stability of Ferrihydrite derived artificially from ferritin.
Andreas Kappler - One of the best experts on this subject based on the ideXlab platform.
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effect of natural organic matter on the fate of cadmium during microbial Ferrihydrite reduction
Environmental Science & Technology, 2020Co-Authors: Zhe Zhou, Andreas Kappler, Marie E Muehe, Elizabeth J Tomaszewski, Juan S Lezamapacheco, James M ByrneAbstract:Natural organic matter (NOM) is known to affect the microbial reduction and transformation of Ferrihydrite, but its implication toward cadmium (Cd) associated with Ferrihydrite is not well-known. H...
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sulfur species as redox partners and electron shuttles for Ferrihydrite reduction by sulfurospirillum deleyianum
Applied and Environmental Microbiology, 2014Co-Authors: Regina Lohmayer, Tina Losekannbehrens, Andreas Kappler, Britta PlanerfriedrichAbstract:ABSTRACT Iron(III) (oxyhydr)oxides can represent the dominant microbial electron acceptors under anoxic conditions in many aquatic environments, which makes understanding the mechanisms and processes regulating their dissolution and transformation particularly important. In a previous laboratory-based study, it has been shown that 0.05 mM thiosulfate can reduce 6 mM Ferrihydrite indirectly via enzymatic reduction of thiosulfate to sulfide by the sulfur-reducing bacterium Sulfurospirillum deleyianum, followed by abiotic reduction of Ferrihydrite coupled to reoxidation of sulfide. Thiosulfate, elemental sulfur, and polysulfides were proposed as reoxidized sulfur species functioning as electron shuttles. However, the exact electron transfer pathway remained unknown. Here, we present a detailed analysis of the sulfur species involved. Apart from thiosulfate, substoichiometric amounts of sulfite, tetrathionate, sulfide, or polysulfides also initiated Ferrihydrite reduction. The portion of thiosulfate produced during abiotic Ferrihydrite-dependent reoxidation of sulfide was about 10% of the total sulfur at maximum. The main abiotic oxidation product was elemental sulfur attached to the iron mineral surface, which indicates that direct contact between microorganisms and Ferrihydrite is necessary to maintain the iron reduction process. Polysulfides were not detected in the liquid phase. Minor amounts were found associated either with microorganisms or the mineral phase. The abiotic oxidation of sulfide in the reaction with Ferrihydrite was identified as rate determining. Cysteine, added as a sulfur source and a reducing agent, also led to abiotic Ferrihydrite reduction and therefore should be eliminated when sulfur redox reactions are investigated. Overall, we could demonstrate the large impact of intermediate sulfur species on biogeochemical iron transformations.
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influence of humic acid imposed changes of Ferrihydrite aggregation on microbial fe iii reduction
Geochimica et Cosmochimica Acta, 2012Co-Authors: Katja Amstaetter, Thomas Borch, Andreas KapplerAbstract:Microbial reduction of Fe(III) minerals at neutral pH is faced by the problem of electron transfer from the cells to the solid-phase electron acceptor and is thought to require either direct cell-mineral contact, the presence of Fe(III)-chelators or the presence of electron shuttles, e.g. dissolved or solid-phase humic substances (HS). In this study we investigated to which extent the ratio of Pahokee Peat Humic Acids (HA) to Ferrihydrite in the presence and absence of phosphate influences rates of Fe(III) reduction by Shewanella oneidensis MR-1 and the identity of the minerals formed. We found that phosphate generally decreased reduction rates by sorption to the Ferrihydrite and surface site blocking. In the presence of low Ferrihydrite concentrations (5 mM), the addition of HA helped to overcome this inhibiting effect by functioning as electron shuttle between cells and the Ferrihydrite. In contrast, at high Ferrihydrite concentrations (30 mM), the addition of HA did not lead to an increase but rather to a decrease in reduction rates. Confocal laser scanning microscopy images and Ferrihydrite sedimentation behaviour suggest that the extent of Ferrihydrite surface coating by HA influences the aggregation of the Ferrihydrite particles and thereby their accessibility for Fe(III)-reducing bacteria. We further conclude that in presence of dissolved HA, iron reduction is stimulated through electron shuttling while in the presence of only sorbed HA, no stimulation by electron shuttling takes place. In presence of phosphate the stimulation effect did not occur until a minimum concentration of 10 mg/l of dissolved HA was reached followed by increasing Fe(III) reduction rates up to dissolved HA concentrations of approximately 240 mg/l above which the electron shuttling effect ceased. Not only Fe(III) reduction rates but also the mineral
Britta Planerfriedrich - One of the best experts on this subject based on the ideXlab platform.
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sulfur species as redox partners and electron shuttles for Ferrihydrite reduction by sulfurospirillum deleyianum
Applied and Environmental Microbiology, 2014Co-Authors: Regina Lohmayer, Tina Losekannbehrens, Andreas Kappler, Britta PlanerfriedrichAbstract:ABSTRACT Iron(III) (oxyhydr)oxides can represent the dominant microbial electron acceptors under anoxic conditions in many aquatic environments, which makes understanding the mechanisms and processes regulating their dissolution and transformation particularly important. In a previous laboratory-based study, it has been shown that 0.05 mM thiosulfate can reduce 6 mM Ferrihydrite indirectly via enzymatic reduction of thiosulfate to sulfide by the sulfur-reducing bacterium Sulfurospirillum deleyianum, followed by abiotic reduction of Ferrihydrite coupled to reoxidation of sulfide. Thiosulfate, elemental sulfur, and polysulfides were proposed as reoxidized sulfur species functioning as electron shuttles. However, the exact electron transfer pathway remained unknown. Here, we present a detailed analysis of the sulfur species involved. Apart from thiosulfate, substoichiometric amounts of sulfite, tetrathionate, sulfide, or polysulfides also initiated Ferrihydrite reduction. The portion of thiosulfate produced during abiotic Ferrihydrite-dependent reoxidation of sulfide was about 10% of the total sulfur at maximum. The main abiotic oxidation product was elemental sulfur attached to the iron mineral surface, which indicates that direct contact between microorganisms and Ferrihydrite is necessary to maintain the iron reduction process. Polysulfides were not detected in the liquid phase. Minor amounts were found associated either with microorganisms or the mineral phase. The abiotic oxidation of sulfide in the reaction with Ferrihydrite was identified as rate determining. Cysteine, added as a sulfur source and a reducing agent, also led to abiotic Ferrihydrite reduction and therefore should be eliminated when sulfur redox reactions are investigated. Overall, we could demonstrate the large impact of intermediate sulfur species on biogeochemical iron transformations.
Wenfeng Tan - One of the best experts on this subject based on the ideXlab platform.
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Solar Irradiation Induced Transformation of Ferrihydrite in the Presence of Aqueous Fe2.
Environmental science & technology, 2019Co-Authors: Zhipeng Shu, Wenfeng Tan, Lihu Liu, Steven L. Suib, Guohong Qiu, Xiong Yang, Lirong Zheng, Fan LiuAbstract:Ferrihydrite commonly occurs in soils and sediments, especially in acid mine drainage (AMD). Solar irradiation may affect Fe(II)-catalyzed transformation of metastable Ferrihydrite to more stable i...
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Roles of different types of oxalate surface complexes in dissolution process of Ferrihydrite aggregates.
Scientific reports, 2018Co-Authors: Luuk K Koopal, Wenfeng TanAbstract:The dissolution of Ferrihydrite induced by low molar mass (LMM) organics is an important process that provides bioavailable iron for organisms. Here, ATR-FTIR analysis was combined with characterization of Ferrihydrite nanoparticles and kinetic modeling to investigate the roles of different oxalate surface complex species in the dissolution of Ferrihydrite aggregates. ATR-FTIR results revealed that at least four different species were present at or near the Ferrihydrite surface in the process of Ferrihydrite aggregate dissolution. At a relatively low addition of oxalate (oxalate/Fe
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Effect of citrate on the species and levels of Al impurities in Ferrihydrite
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2018Co-Authors: Luuk K Koopal, Wenfeng TanAbstract:Abstract Ferrihydrite in natural environment is commonly produced in the presence of significant amounts of Al and low molar mass organic impurities, which affect the surface reactivity of Ferrihydrite depending on the impurity levels. Here, we investigated the effect of citrate on the species and levels of Al impurities in Ferrihydrite. Al-bearing Ferrihydrite was synthesized at different citrate/(Fe + Al) and Al/(Fe + Al) molar ratios. The samples were then characterized by chemical analysis, TEM, XRD, XPS and FTIR. The results showed that citrate promoted the formation of stable colloidal Ferrihydrite particles, and induced Al accumulation in colloidal fraction at the citrate/(Fe + Al) ratio of 25% as well as in the surface layer of Ferrihydrite at the citrate/(Fe + Al) ratios of 25 and 50 mol%. DFT analysis showed that Al-for-Fe substitution was closely related to the particular sites in Ferrihydrite structure. We also estimated the mass of citrate (or aluminum citrate complexes) required to occupy the reactive sites on Ferrihydrite nanoparticles. The results revealed that with increasing citrate content, the surface reactive sites favorable for Al-substitution of Ferrihydrite became occupied by adsorbed citrate, which partially inhibited the substitution of Fe by Al but increased the adsorption of Al through Al-citrate surface complexation.
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Efficient catalytic As(III) oxidation on the surface of Ferrihydrite in the presence of aqueous Mn(II).
Water research, 2017Co-Authors: Shuai Lan, Xiaoming Wang, Jing Zhang, Wenfeng Tan, Hong Ying, Fan Liu, Qiaoyun Huang, Xionghan FengAbstract:Arsenic is a carcinogenic element that exists primarily as arsenate [As(V)] and arsenite [As(III)] in the nature environment, with As(III) being more toxic and mobile of the two species. In addition, Ferrihydrite, which is widely distributed in soils and aquatic environments, can catalyze the oxidation of Mn(II) and accelerate the formation of high-valence Mn, which can significantly influence the speciation, toxicity, and mobility of As when these species co-exist. In this context, we herein explored the mechanism of As(III) oxidation in the presence of Ferrihydrite and Mn(II) using a kinetic approach combined with multiple spectroscopic techniques, including X-ray absorption near edge spectroscopy, in situ horizontal attenuated total-reflectance Fourier transform infrared spectroscopy, and in situ quick scanning X-ray absorption spectroscopy. Our results indicate that efficient As(III) oxidation by dissolved O2 occurs on the surface of Ferrihydrite in the presence of aqueous Mn(II). Compared with As(III) oxidation in the presence of Ferrihydrite and Mn oxides (i.e., Mn oxides/hydroxides), the degree of As(III) oxidation in the Ferrihydrite-Mn(II) system was significantly higher, and the majority of generated As(V) was adsorbed on the mineral (i.e., Ferrihydrite) surface. Furthermore, As(III) oxidation was enhanced upon increasing both the molar ratio of Mn(II)/As(III) and the solution pH. The greater As(III) oxidation by O2 in the Ferrihydrite-Mn(II) system was mainly attributed to the formation of a strong oxidant of the instantaneous intermediate Mn(III) species via Mn(II) oxidation under catalysis by the Ferrihydrite surface. Moreover, As(III) oxidation occurred mainly on the Ferrihydrite surface and was accompanied by the regeneration of Mn(II), thereby rendering it recyclable. These results therefore provide new insights into the mechanism of As(III) oxidation on the surfaces of Fe oxides (i.e., Fe oxides/hydroxides) in the presence of aqueous Mn(II) as well as the new details regarding the electron transfer mechanisms between the As(III)-Mn(II, III)-O2 species at the Ferrihydrite surface, and could lead to novel approaches for As(III) contaminant remediation in the environment.
Yongfeng Jia - One of the best experts on this subject based on the ideXlab platform.
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arsenic redistribution and transformation during fe ii catalyzed recrystallization of as adsorbed Ferrihydrite under anaerobic conditions
Chemical Geology, 2019Co-Authors: Guoqing Zhang, Zidan Yuan, Lei Lei, Jinru Lin, Xin Wang, Shaofeng Wang, Yongfeng JiaAbstract:Abstract The redistribution and transformation of arsenic (As) during the Fe(II)-catalyzed transformation of As-adsorbed Ferrihydrite remains unclear. This study investigated the re-crystallization process and products of As-adsorbed Ferrihydrite accelerated by Fe(II) and the fate of arsenate and arsenite at pH 7 under anaerobic condition. Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), transmission electron microscopy (TEM), and synchrotron based X-ray absorption near edge structure (XANES) were utilized for the As and Fe speciation analysis. Results showed that both As(V) and As(III) can retard the transformation of Ferrihydrite. The concentration and speciation of As strongly influenced the mineralogy and morphology of produced crystalline Fe oxyhydroxides. The higher As(V) loading (Fe/As = 40–100) resulted in the conversion of most Ferrihydrite to lepidocrocite instead of goethite. The adsorbed As(III) showed weak effect on the re-crystallization of Ferrihydrite at the early stage. A considerable fraction of As(III) (70–80%) was oxidized to As(V) during the Fe(II) catalyzed transformation of As(III)-adsorbed Ferrihydrite. The oxidation of As(III) to As(V) in turn retarded the transformation of the remaining Ferrihydrite to goethite and induced the production of a small amount of lepidocrocite. A temporary release of As(V) was observed during the first 5 days and the released As(V) was re-adsorbed back to the crystalline products, whereas no As was released to the aqueous phase in the As(III)-Ferrihydrite systems. During the re-crystallization of Ferrihydrite, 1 M phosphate-extractable As decreased quickly by up to 90% in the solid phase, indicating that partial As transformed to more stable phase. Our results suggested that Fe(II)-catalytic transformation of As-adsorbed Ferrihydrite could help reducing the mobility and toxicity of As in anoxic aquifers.
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Effect of sulfide on As(III) and As(V) sequestration by Ferrihydrite
Chemosphere, 2017Co-Authors: Zhixi Zhao, Shaofeng Wang, Yongfeng JiaAbstract:The sulfide-induced change in arsenic speciation is often coupled to iron geochemical processes, including redox reaction, adsorption/desorption and precipitation/dissolution. Knowledge about how sulfide influenced the coupled geochemistry of iron and arsenic was not explored well up to now. In this work, retention and mobilization of As(III) and As(V) on Ferrihydrite in sulfide-rich environment was studied. The initial oxidation states of arsenic and the contact order of sulfide notably influenced arsenic sequestration on Ferrihydrite. For As(III) systems, pre-sulfidation of As(III) decreased arsenic sequestration mostly. The arsenic adsorption capacity decreased about 50% in comparison with the system without sulfide addition. For As(V) systems, pre-sulfidation of Ferrihydrite decreased 30% sequestration of arsenic on Ferrihydrite. Reduction of Ferrihydrite by sulfide in As(V) system was higher than that in As(III) system. Geochemical modeling calculations identified formation of thioarsenite in the pre-sulfidation of As(III) system. Formation of arsenic thioanions enhanced As solubility in the pre-sulfidation of As(III) system. The high concentration of sulfide and Fe(II) in pre-sulfidation of Ferrihydrite system contributed to saturation of FeS. This supplied new solid phase to immobilize soluble arsenic in aqueous phase. X-ray absorption near edge spectroscopy (XANES) of sulfur K-edge, arsenic K-edge and iron L-edge analysis gave the consistent evidence for the sulfidation reaction of arsenic and Ferrihydrite under specific geochemical settings.
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Adsorption and heterogeneous oxidation of As(III) on Ferrihydrite
Water research, 2011Co-Authors: Zhixi Zhao, Yongfeng Jia, Shanlin ZhaoAbstract:Redox transformation of arsenic strongly influences its fate and transport in the environment. It is of interest to investigate heterogeneous oxidation of As(III) on the surface of major metal oxide in sediments. Whether As(III) can be oxidized on Ferrihydrite and the role Ferrihydrite plays as catalyst or oxidant are inconsistent in previous researches. In this work, oxidation of As(III) on Ferrihydrite was studied by analysis of dissolved and adsorbed As(III) and As(V) quantitatively and qualitatively. X-ray absorption near edge spectroscopy (XANES) and pHpznpc (point of zero net proton charge) of Ferrihydrite with adsorbed As(III) showed clear evidence for partial oxidation on Ferrihydrite. Oxidation of As(III) occurred when it was brought to contact with Ferrihydrite at high Fe/As molar ratio (i.e. 50, 200). The concentration of As(V) in solid phase increased gradually while adsorbed As(III) concentration dropped. Fe(II) was not detectable during the oxidation of As(III). These results showed that Ferrihydrite had the catalytic effect on oxidation of As(III). Only a fraction of As(III) was oxidized even when the system was exposed to air. The effects of Ferrihydrite aging, media pH, coexistence of ions on As(III) oxidation were also investigated. The results suggest that catalytic oxidation of As(III) on Ferrihydrite may play a role in geochemical cycling of arsenic in environment.
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adsorption of arsenate onto Ferrihydrite from aqueous solution influence of media sulfate vs nitrate added gypsum and ph alteration
Environmental Science & Technology, 2005Co-Authors: Yongfeng Jia, George P DemopoulosAbstract:Mineral processing effluents generated in hydrometallurgical industrial operations are sulfate based; hence it is of interest to investigate the effect sulfate matrix solution ("sulfate media") has on arsenate adsorption onto Ferrihydrite. In this work, in particular, the influence of media (SO42- vs NO3-), added gypsum, and pH alteration on the adsorption of arsenate onto Ferrihydrite has been studied. The Ferrihydrite precipitated from sulfate solution incorporated a significant amount of sulfate ions and showed a much higher adsorption capacity for arsenate compared to nitrate-Ferrihydrite at pH 3-8 and initial Fe/As molar ratios of 2, 4, and 8. Adsorption of arsenate onto sulfate-Ferrihydrite involved ligand exchange with SO42- ions that were found to be more easily exchangeable with increasing pH. Added gypsum to the adsorption system significantly enhanced the uptake of arsenate by Ferrihydrite at pH 8. Equilibration treatment at acidic pH and addition of gypsum markedly improved the stability of adsorbed arsenate on Ferrihydrite when pH was elevated. Comparison of arsenate adsorption onto Ferrihydrite to coprecipitation of arsenate with iron(III) showed the latter process to lead to higher arsenic removal.