Preference of Co over Al for substitution of Fe in goethite (α-FeOOH) structure: Mechanism revealed from EXAFS, XPS, DFT and linear free energy correlation model

Yin, Hui; Wu, Yang; Hou, Jingtao; Yan, Xinran; Li, Zhaohui; Zhu, Chen; Zhang, Jing; Feng, Xionghan; Tan, Wei; Liu, Fan

doi:10.1016/j.chemgeo.2019.119378

Cited by 19 publications

(9 citation statements)

References 77 publications

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“…pH and temperature. Generally, a high concentration of OHand high temperature favors the oxidation (Alvarez et al, 2008;Pozas et al, 2004;Yin et al, 2020b). The coexistence of Co 2+ and Co 3+ in the doped hausmannite samples is similar to that observed in Co-doped goethite samples in our previous study (Yin et al, 2020a), both owing to the low alkalinity and low temperature used.…”

Section: Co Valence and Crystal Chemistry In Co-doped Hausmannitesupporting

confidence: 86%

Effects of Co doping on the structure and physicochemical properties of hausmannite (Mn3O4) and its transformation during aging

Zhang

et al. 2021

Chemical Geology

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Section: Co Valence and Crystal Chemistry In Co-doped Hausmannitesupporting

confidence: 86%

Effects of Co doping on the structure and physicochemical properties of hausmannite (Mn3O4) and its transformation during aging

Zhang

et al. 2021

Chemical Geology

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“…Co II adsorption on ferrihydrite is responsible for the decrease in the Co III /Co II redox potential in response to increasing pH, where Co II becomes a reducing agent for Fe III in ferrihydrite [92,[95][96][97][98]. When sorbed on ferrihydrite, Co II is oxidized to sorbed Co III in agreement with the electron transfer to Fe III atoms, which are reduced to Fe II [95,[97][98][99][100][101]. Simultaneously, both sorbed Co III and free Co II hydrolysis are responsible for H + generation, which facilitates local dissolution of ferrihydrite.…”

Section: Discussionmentioning

confidence: 98%

Comprehension of the Route for the Synthesis of Co/Fe LDHs via the Method of Coprecipitation with Varying pH

et al. 2022

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Co/Fe-based layered double hydroxides (LDHs) are among the most promising materials for electrochemical applications, particularly in the development of energy storage devices, such as electrochemical capacitors. They have also been demonstrated to function as energy conversion catalysts in photoelectrochemical applications for CO2 conversion into valuable chemicals. Understanding the formation mechanisms of such compounds is therefore of prime interest for further controlling the chemical composition, structure, morphology, and/or reactivity of synthesized materials. In this study, a combination of X-ray diffraction, vibrational and absorption spectroscopies, as well as physical and chemical analyses were used to provide deep insight into the coprecipitation formation mechanisms of Co/Fe-based LDHs under high supersaturation conditions. This procedure consists of adding an alkaline aqueous solution (2.80 M NaOH and 0.78 M Na2CO3) into a cationic solution (0.15 M CoII and 0.05 M FeIII) and varying the pH until the desired pH value is reached. Beginning at pH 2, pH increases induce precipitation of FeIII as ferrihydrite, which is the pristine reactional intermediate. From pH > 2, CoII sorption on ferrihydrite promotes a redox reaction between FeIII of ferrihydrite and the sorbed CoII. The crystallinity of the poorly crystalized ferrihydrite progressively decreases with increasing pH. The combination of such a phenomenon with the hydrolysis of both the sorbed CoIII and free CoII generates pristine hydroxylated FeII/CoIII LDHs at pH 7. Above pH 7, free CoII hydrolysis proceeds, which is responsible for the local dissolution of pristine LDHs and their reprecipitation and then 3D organization into CoII4FeII2CoIII2 LDHs. The progressive incorporation of CoII into the LDH structure is accountable for two phenomena: decreased coulombic attraction between the positive surface-charge sites and the interlayer anions and, concomitantly, the relative redox potential evolution of the redox species, such as when FeII is re-oxidized to FeIII, while CoIII is re-reduced to CoII, returning to a CoII6FeIII2 LDH. The nature of the interlamellar species (OH−, HCO3−, CO32− and NO3−) depends on their mobility and the speciation of anions in response to changing pH.

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“…Cadmium (Cd) is a highly toxic and carcinogenic heavy metal for humans without a safe exposure limit. − Risk prediction and remediation of anthropogenic Cd pollution in terrestrial environments require a fundamental understanding of its geochemical cycling. Recently, Cd isotope signatures have been increasingly applied to understand biogeochemical reactions and fingerprint Cd sources and fate in contaminated ecosystems. − However, this promise is hampered as multiple processes can cause heavy-metal isotope fractionation, such as adsorption onto mineral surfaces, , coprecipitation with minerals, , complexation by inorganic or organic ligands, , membrane protein transport in plants, and weathering. , Among these processes, adsorption and coprecipitation on mineral surfaces or structural incorporation into mineral lattices are of much importance, which are the well-known association mechanisms of heavy metals with minerals, particularly for Cd, Zn, and Ni. ,− …”

Section: Introductionmentioning

confidence: 99%

Cadmium Isotope Fractionation during Adsorption and Substitution with Iron (Oxyhydr)oxides

Yan

Zhu

et al. 2021

Environ. Sci. Technol.

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Cadmium (Cd) isotopes have great potential for understanding Cd geochemical cycling in soil and aquatic systems. Iron (oxyhydr)oxides can sequester Cd via adsorption and isomorphous substitution, but how these interactions affect Cd isotope fractionation remains unknown. Here, we show that adsorption preferentially enriches lighter Cd isotopes on iron (oxyhydr)oxide surfaces through equilibrium fractionation, with a similar fractionation magnitude (Δ114/110Cdsolid‑solution) for goethite (Goe) (−0.51 ± 0.04‰), hematite (Hem) (−0.54 ± 0.10‰), and ferrihydrite (Fh) (−0.55 ± 0.03‰). Neither the initial Cd2+ concentration or ionic strength nor the pH influence the fractionation magnitude. The enrichment of the light isotope is attributed to the adsorption of highly distorted [CdO6] on solids, as indicated by Cd K-edge extended X-ray absorption fine-structure analysis. In contrast, Cd incorporation into Goe by substitution for lattice Fe at a Cd/Fe molar ratio of 0.05 preferentially sequesters heavy Cd isotopes, with a Δ114/110Cdsolid‑solution of 0.22 ± 0.01‰. The fractionation probably occurs during the transformation of Fh into Goe via dissolution and reprecipitation. These results improve the understanding of the Cd isotope fractionation behavior being affected by iron (oxyhydr)oxides in Earth’s critical zone and demonstrate that interactions with minerals can obscure anthropogenic and natural Cd isotope characteristics, which should be carefully considered when applying Cd isotopes as environmental tracers.

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Preference of Co over Al for substitution of Fe in goethite (α-FeOOH) structure: Mechanism revealed from EXAFS, XPS, DFT and linear free energy correlation model

Cited by 19 publications

References 77 publications

Effects of Co doping on the structure and physicochemical properties of hausmannite (Mn3O4) and its transformation during aging

Effects of Co doping on the structure and physicochemical properties of hausmannite (Mn3O4) and its transformation during aging

Comprehension of the Route for the Synthesis of Co/Fe LDHs via the Method of Coprecipitation with Varying pH

Cadmium Isotope Fractionation during Adsorption and Substitution with Iron (Oxyhydr)oxides

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