Effect of Fe oxidation state (+2 versus +3) in precursor on the structure of Fe oxides/carbonates-based composites examined by XPS, FTIR and EXAFS

Natalia Chubar; Vasyl Gerda; Malgorzata Szlachta; Ganna Yablokova

doi:10.1016/j.solidstatesciences.2021.106752

Effect of Fe oxidation state (+2 versus +3) in precursor on the structure of Fe oxides/carbonates-based composites examined by XPS, FTIR and EXAFS

Natalia Chubar^*, Vasyl Gerda, Malgorzata Szlachta, Ganna Yablokova

^*Corresponding author for this work

DES - Geochemistry group

KU Leuven

Research output: Contribution to journal › Article › Academic › peer-review

Abstract

Here we investigate the influence of Fe oxidation state (either Fe(II) or Fe(III) sulfates) in precursor of the same chemical composition on the atomic scale structure, surface speciation and adsorptive anion removal of the purely inorganic composites produced under the urea supported hydrothermal synthesis. In case of utilization of Fe³⁺ precursor, the materials chemistry was solely dominated by the formation of highly crystalline Fe(III) oxides, however the particle surfaces were covered with small quantities of FeCO₃ (not detectable by EXAFS/XANES/FTIR) precipitated after the autoclave was turned off. Within the reactive medium with Fe²⁺ precursor, due to high pressure in autoclave which facilitated reducing conditions and sedimentation of Fe divalent, two main processes took place one of which was the formation of Fe hydrous oxides; the second reaction resulted in generation of FeCO₃, which become a predominant phase in volume averaged composition. Notably, despite the prevalence of Fe(II) carbonates in bulk structure, the narrow upper layers (XPS detectable) was enriched with Fe(III) oxides. At the chosen autoclave temperature of 150 °C, both samples had low hydration of physisorbed water, which confirmed our recent hypothesis about correlation between Fe (or another metal formed oxides) local structure in outer shells fitted with several (many) oxygen atoms and the material hydration with physisorbed water. None of the two composites demonstrated strong adsorptive removal of seven anions (F⁻, Br⁻, BrO₃⁻, HAsO₄²⁻, H₃AsO₃, HPO₄²⁻, SeO₄²⁻), which verified another idea about the interdependence of distinguished (EXAFS simulated) outer shells of metals (here, Fe) fitted with two paths simultaneously ({Fe–Fe}+{Fe–O}) one peak and the anion exchange potential. Overall, the Fe(III)-precursor product was more crystalline, less heterogeneous (fewer phases), showed worse anion uptake than the other sample. The material prepared from Fe(II) precursor is considered to be a promising precursor for further phase transformations via thermal or hydrothermal treatments (due to generous presence of FeCO₃).

Original language	English
Article number	106752
Pages (from-to)	1-13
Number of pages	13
Journal	Solid State Sciences
Volume	121
DOIs	https://doi.org/10.1016/j.solidstatesciences.2021.106752
Publication status	Published - Nov 2021

Bibliographical note

Funding Information:
King Abdullah University of Science and Technology ( KAUST ) (Saudi Arabia), which funded this research via the Global Research Partnership program (renamed for Global Collaborative Research) (award № KUK-C1-017-12 ), and Dutch Research Council ( NWO ) (Netherlands), which financed EXAFS/XANES studies at Dutch-Belgian Beamline (DUBBLE) in 2010 at the European Synchrotron Radiation Facility (ESRF) (France), are gratefully acknowledged. The authors thank Dr. Andrey Shchukarev (Umeå University, Sweden) for XPS analysis and all XPS spectra treatments (deconvolutions). The authors are much obliged to Editor and anonymous Reviewers for their helpful comments which resulted in the improved paper.

Publisher Copyright:
© 2021 The Authors

Keywords

EXAFS (Extended x-ray absorption fine structure)
Hydrothermal urea-supported precipitation
Iron oxides/carbonates-based composites
Sorption of anions
XPS (X-ray photoelectron spectroscopy)

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10.1016/j.solidstatesciences.2021.106752

1-s2.0-S129325582100220X-mainFinal published version, 5.88 MBLicence: Taverne

Cite this

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title = "Effect of Fe oxidation state (+2 versus +3) in precursor on the structure of Fe oxides/carbonates-based composites examined by XPS, FTIR and EXAFS",

abstract = "Here we investigate the influence of Fe oxidation state (either Fe(II) or Fe(III) sulfates) in precursor of the same chemical composition on the atomic scale structure, surface speciation and adsorptive anion removal of the purely inorganic composites produced under the urea supported hydrothermal synthesis. In case of utilization of Fe3+ precursor, the materials chemistry was solely dominated by the formation of highly crystalline Fe(III) oxides, however the particle surfaces were covered with small quantities of FeCO3 (not detectable by EXAFS/XANES/FTIR) precipitated after the autoclave was turned off. Within the reactive medium with Fe2+ precursor, due to high pressure in autoclave which facilitated reducing conditions and sedimentation of Fe divalent, two main processes took place one of which was the formation of Fe hydrous oxides; the second reaction resulted in generation of FeCO3, which become a predominant phase in volume averaged composition. Notably, despite the prevalence of Fe(II) carbonates in bulk structure, the narrow upper layers (XPS detectable) was enriched with Fe(III) oxides. At the chosen autoclave temperature of 150 °C, both samples had low hydration of physisorbed water, which confirmed our recent hypothesis about correlation between Fe (or another metal formed oxides) local structure in outer shells fitted with several (many) oxygen atoms and the material hydration with physisorbed water. None of the two composites demonstrated strong adsorptive removal of seven anions (F−, Br−, BrO3−, HAsO42−, H3AsO3, HPO42−, SeO42−), which verified another idea about the interdependence of distinguished (EXAFS simulated) outer shells of metals (here, Fe) fitted with two paths simultaneously (\{Fe–Fe\}+\{Fe–O\}) one peak and the anion exchange potential. Overall, the Fe(III)-precursor product was more crystalline, less heterogeneous (fewer phases), showed worse anion uptake than the other sample. The material prepared from Fe(II) precursor is considered to be a promising precursor for further phase transformations via thermal or hydrothermal treatments (due to generous presence of FeCO3).",

keywords = "EXAFS (Extended x-ray absorption fine structure), Hydrothermal urea-supported precipitation, Iron oxides/carbonates-based composites, Sorption of anions, XPS (X-ray photoelectron spectroscopy)",

author = "Natalia Chubar and Vasyl Gerda and Malgorzata Szlachta and Ganna Yablokova",

note = "Funding Information: King Abdullah University of Science and Technology ( KAUST ) (Saudi Arabia), which funded this research via the Global Research Partnership program (renamed for Global Collaborative Research) (award № KUK-C1-017-12 ), and Dutch Research Council ( NWO ) (Netherlands), which financed EXAFS/XANES studies at Dutch-Belgian Beamline (DUBBLE) in 2010 at the European Synchrotron Radiation Facility (ESRF) (France), are gratefully acknowledged. The authors thank Dr. Andrey Shchukarev (Ume{\aa} University, Sweden) for XPS analysis and all XPS spectra treatments (deconvolutions). The authors are much obliged to Editor and anonymous Reviewers for their helpful comments which resulted in the improved paper. Publisher Copyright: {\textcopyright} 2021 The Authors",

year = "2021",

month = nov,

doi = "10.1016/j.solidstatesciences.2021.106752",

language = "English",

volume = "121",

pages = "1--13",

journal = "Solid State Sciences",

issn = "1293-2558",

publisher = "Elsevier Masson s.r.l.",

}

TY - JOUR

T1 - Effect of Fe oxidation state (+2 versus +3) in precursor on the structure of Fe oxides/carbonates-based composites examined by XPS, FTIR and EXAFS

AU - Chubar, Natalia

AU - Gerda, Vasyl

AU - Szlachta, Malgorzata

AU - Yablokova, Ganna

N1 - Funding Information: King Abdullah University of Science and Technology ( KAUST ) (Saudi Arabia), which funded this research via the Global Research Partnership program (renamed for Global Collaborative Research) (award № KUK-C1-017-12 ), and Dutch Research Council ( NWO ) (Netherlands), which financed EXAFS/XANES studies at Dutch-Belgian Beamline (DUBBLE) in 2010 at the European Synchrotron Radiation Facility (ESRF) (France), are gratefully acknowledged. The authors thank Dr. Andrey Shchukarev (Umeå University, Sweden) for XPS analysis and all XPS spectra treatments (deconvolutions). The authors are much obliged to Editor and anonymous Reviewers for their helpful comments which resulted in the improved paper. Publisher Copyright: © 2021 The Authors

PY - 2021/11

Y1 - 2021/11

N2 - Here we investigate the influence of Fe oxidation state (either Fe(II) or Fe(III) sulfates) in precursor of the same chemical composition on the atomic scale structure, surface speciation and adsorptive anion removal of the purely inorganic composites produced under the urea supported hydrothermal synthesis. In case of utilization of Fe3+ precursor, the materials chemistry was solely dominated by the formation of highly crystalline Fe(III) oxides, however the particle surfaces were covered with small quantities of FeCO3 (not detectable by EXAFS/XANES/FTIR) precipitated after the autoclave was turned off. Within the reactive medium with Fe2+ precursor, due to high pressure in autoclave which facilitated reducing conditions and sedimentation of Fe divalent, two main processes took place one of which was the formation of Fe hydrous oxides; the second reaction resulted in generation of FeCO3, which become a predominant phase in volume averaged composition. Notably, despite the prevalence of Fe(II) carbonates in bulk structure, the narrow upper layers (XPS detectable) was enriched with Fe(III) oxides. At the chosen autoclave temperature of 150 °C, both samples had low hydration of physisorbed water, which confirmed our recent hypothesis about correlation between Fe (or another metal formed oxides) local structure in outer shells fitted with several (many) oxygen atoms and the material hydration with physisorbed water. None of the two composites demonstrated strong adsorptive removal of seven anions (F−, Br−, BrO3−, HAsO42−, H3AsO3, HPO42−, SeO42−), which verified another idea about the interdependence of distinguished (EXAFS simulated) outer shells of metals (here, Fe) fitted with two paths simultaneously ({Fe–Fe}+{Fe–O}) one peak and the anion exchange potential. Overall, the Fe(III)-precursor product was more crystalline, less heterogeneous (fewer phases), showed worse anion uptake than the other sample. The material prepared from Fe(II) precursor is considered to be a promising precursor for further phase transformations via thermal or hydrothermal treatments (due to generous presence of FeCO3).

AB - Here we investigate the influence of Fe oxidation state (either Fe(II) or Fe(III) sulfates) in precursor of the same chemical composition on the atomic scale structure, surface speciation and adsorptive anion removal of the purely inorganic composites produced under the urea supported hydrothermal synthesis. In case of utilization of Fe3+ precursor, the materials chemistry was solely dominated by the formation of highly crystalline Fe(III) oxides, however the particle surfaces were covered with small quantities of FeCO3 (not detectable by EXAFS/XANES/FTIR) precipitated after the autoclave was turned off. Within the reactive medium with Fe2+ precursor, due to high pressure in autoclave which facilitated reducing conditions and sedimentation of Fe divalent, two main processes took place one of which was the formation of Fe hydrous oxides; the second reaction resulted in generation of FeCO3, which become a predominant phase in volume averaged composition. Notably, despite the prevalence of Fe(II) carbonates in bulk structure, the narrow upper layers (XPS detectable) was enriched with Fe(III) oxides. At the chosen autoclave temperature of 150 °C, both samples had low hydration of physisorbed water, which confirmed our recent hypothesis about correlation between Fe (or another metal formed oxides) local structure in outer shells fitted with several (many) oxygen atoms and the material hydration with physisorbed water. None of the two composites demonstrated strong adsorptive removal of seven anions (F−, Br−, BrO3−, HAsO42−, H3AsO3, HPO42−, SeO42−), which verified another idea about the interdependence of distinguished (EXAFS simulated) outer shells of metals (here, Fe) fitted with two paths simultaneously ({Fe–Fe}+{Fe–O}) one peak and the anion exchange potential. Overall, the Fe(III)-precursor product was more crystalline, less heterogeneous (fewer phases), showed worse anion uptake than the other sample. The material prepared from Fe(II) precursor is considered to be a promising precursor for further phase transformations via thermal or hydrothermal treatments (due to generous presence of FeCO3).

KW - EXAFS (Extended x-ray absorption fine structure)

KW - Hydrothermal urea-supported precipitation

KW - Iron oxides/carbonates-based composites

KW - Sorption of anions

KW - XPS (X-ray photoelectron spectroscopy)

UR - https://www.scopus.com/pages/publications/85117263120

U2 - 10.1016/j.solidstatesciences.2021.106752

DO - 10.1016/j.solidstatesciences.2021.106752

M3 - Article

SN - 1293-2558

VL - 121

SP - 1

EP - 13

JO - Solid State Sciences

JF - Solid State Sciences

M1 - 106752

ER -

Effect of Fe oxidation state (+2 versus +3) in precursor on the structure of Fe oxides/carbonates-based composites examined by XPS, FTIR and EXAFS

Abstract

Bibliographical note

Keywords

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