Mechanistic Study for Antimony Adsorption and Precipitation on Hematite Facets

Li, Yan; Chan, Ting‐Shan; Jing, Chuanyong

doi:10.1021/acs.est.1c07801

Cited by 41 publications

(14 citation statements)

References 38 publications

(85 reference statements)

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“…Therefore, iron minerals could generate a considerable amount of ROS in the long term and play a role in accelerating biogeochemical processes as well as pollutant dynamics. For instance, previous studies on interactions between pollutants and iron minerals typically focus on interfacial hydrolysis, adsorption, − and immobilization processes; − this study suggests that pollutant transformation processes should be considered with ROS photochemically produced on the iron mineral surface. In other words, the iron mineral surface may act as a hotspot for pollutant transformation.…”

Section: Environmental Implicationsmentioning

confidence: 95%

Sunlight-Driven Production of Reactive Oxygen Species from Natural Iron Minerals: Quantum Yield and Wavelength Dependence

Zheng

Zhou

et al. 2022

Environ. Sci. Technol.

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Photochemically generated reactive oxygen species (ROS) play numerous key roles in earth's surface biogeochemical processes and pollutant dynamics. ROS production has historically been linked to the photosensitization of natural organic matter. Here, we report the photochemical ROS production from three naturally abundant iron minerals. All investigated iron minerals are photoactive toward sunlight irradiation, with photogenerated currents linearly correlated with incident light intensity. Hydroxyl radicals ( • OH) and hydrogen peroxide (H 2 O 2 ) are identified as the major ROS species, with apparent quantum yields ranging from 1.4 × 10 −8 to 3.9 × 10 −8 and 5.8 × 10 −8 to 2.5 × 10 −6 , respectively. Photochemical ROS production exhibits high wavelength dependence, for instance, the • OH quantum yield decreases with the increase of light wavelength from 375 to 425 nm, and above 425 nm it sharply decreases to zero. The temperature shows a positive impact on • OH production, with apparent activation energies ranging from 8.0 to 17.8 kJ/mol. Interestingly, natural iron minerals with impurities exhibit higher ROS production than their pure crystal counterparts. Compared with organic photosensitizers, iron minerals exhibit higher wavelength dependence, higher selectivity, lower efficiency, and long-term stability in photochemical ROS production. Our study highlights natural inorganic iron mineral photochemistry as a ubiquitous yet previously overlooked source of ROS.

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Section: Environmental Implicationsmentioning

confidence: 95%

Sunlight-Driven Production of Reactive Oxygen Species from Natural Iron Minerals: Quantum Yield and Wavelength Dependence

Zheng

Zhou

et al. 2022

Environ. Sci. Technol.

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“…Similar bonding modes were found in Cr(VI), As(III/V), and Sb(III/V) adsorption, which was attributed to semblable R O–O in these anions (2.82–3.09 Å, Figure S7, Table S7). ,, These oxyanions readily form the 1 V complex when R Fe–Fe is significantly larger than R O–O (Figure a). When R Fe–Fe is comparable with R O–O , 2 C complex forms upon adsorption (Figure b).…”

Section: Resultsmentioning

confidence: 99%

Facet-Dependent Atomic Distances Shape Vanadate Adsorption Complexes on Hematite Nanocrystals

Zheng

Zhong

et al. 2023

Langmuir

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The environmental fate of vanadate (V(V)) is significantly influenced by iron oxide nanocrystals through adsorption. Nevertheless, the underlying driving force controlling V(V) adsorption on hematite (Fe2O3) facets is poorly understood. Herein, V(V) adsorption on the {001}, {110}, and {214} Fe2O3 facets was explored using batch adsorption experiments, spectroscopic studies, and density functional theory (DFT) calculations. Adsorption experiments suggested that the order of V(V) adsorption capacity followed {001} > {110} > {214}. However, the affinity of V(V) to the {001} facet was the weakest, as evidenced by its least resistance to phosphate and sulfate competition. Our extended X-ray absorption fine structure (EXAFS) study indicated the formation of the inner-sphere monodentate mononuclear (1V) complex on the {001} facet and bidentate corner-sharing (2C) complexes on the {110} and {214} facets. Density functional theory (DFT) calculations showed the 1V complex is preferable when the adjacent Fe–Fe atomic distance is significantly larger than the O–O atomic distance of V(V). Otherwise, the 2C complex is formed if the distance is comparable. This determining factor in surface complex formation can be safely extended to other oxyanions that the compatibility in the atomic distance of Fe–Fe on Fe2O3 facets and O–O in oxyanions shapes the surface complex. The molecular-level understanding of the facet-dependent adsorption mechanism provides the basis for the design and application of oxyanion adsorbents.

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“…Based on fitting EXAFS data, an Sb−Sb backscattering path was observed when Sb(V) exceeded a monolayer surface coverage, which was interpreted as an indication for a polynuclear surface precipitate. In a more recent study, Yan et al 31 examined surface adsorption and subsequent precipitation of Sb on hematite (Fe 2 O 3 ) facets. They observed that the initial Sb adsorption and the subsequent precipitation were associated with Sb loadings and hematite facets, and an alteration in the surface binding mode of Sb from edge-sharing to corner-sharing may facilitate the formation of NaSb(OH) 6 precipitates.…”

Section: Aqueous Dynamics and Sorption Of As(v) And Sb(v)mentioning

confidence: 99%

Mechanisms of Arsenic and Antimony Co-sorption onto Jarosite: An X-ray Absorption Spectroscopic Study

Karimian

Johnston

Tavakkoli

et al. 2023

Environ. Sci. Technol.

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Jarosite, a common mineral in acidic sulfur-rich environments, can strongly sorb both As(V) and Sb(V). However, little is known regarding the mechanisms that control simultaneous co-sorption of As(V) and Sb(V) to jarosite. We investigated the mechanisms controlling As(V) and Sb(V) sorption to jarosite at pH 3 (in dual and single metalloid treatments). Jarosite was found to sorb Sb(V) to a greater extent than As(V) in both single and dual metalloid treatments. Relative to single metalloid treatments, the dual presence of both As(V) and Sb(V) decreased the sorption of both metalloids by almost 50%. Antimony K-edge EXAFS spectroscopy revealed that surface precipitation of an Sb(V) oxide species was the predominant sorption mechanism for Sb(V). In contrast, As K-edge EXAFS spectroscopy showed that As(V) sorption occurred via bidentate corner-sharing complexes on the jarosite surface when Sb(V) was absent or present at low loadings or by formation of similar complexes on the Sb(V) oxide surface precipitate when Sb(V) was present at high loadings. These results point to a novel mechanism by which Sb(V) impacts the co-sorption of As(V). Overall, these findings highlight a strong contrast in the sorption mechanisms of Sb(V) versus As(V) to jarosite under acidic environmental conditions.

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Mechanistic Study for Antimony Adsorption and Precipitation on Hematite Facets

Cited by 41 publications

References 38 publications

Sunlight-Driven Production of Reactive Oxygen Species from Natural Iron Minerals: Quantum Yield and Wavelength Dependence

Sunlight-Driven Production of Reactive Oxygen Species from Natural Iron Minerals: Quantum Yield and Wavelength Dependence

Facet-Dependent Atomic Distances Shape Vanadate Adsorption Complexes on Hematite Nanocrystals

Mechanisms of Arsenic and Antimony Co-sorption onto Jarosite: An X-ray Absorption Spectroscopic Study

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