Local structure investigation of cobalt ferrite-based nanoparticles by synchrotron X-ray diffraction and absorption spectroscopy

Moreira, A.F.L.; Paula, Fábio Luís de Oliveira; Campos, Alex Fabiano Cortez; Depeyrot, J.

doi:10.1016/j.jssc.2020.121269

Cited by 12 publications

(5 citation statements)

References 36 publications

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“…We also calculated the volume fraction of each spinel phase from the metal concentrations obtained from chemical titration. Knowing the maghemite shell fraction of the samples, which varies from 30% for Co15 to 53% for Co120, it is possible to observe that the shell thickness increases with the duration of the surface chemical conditioning, as expected from previous works [27,40,41]. That morphochemical structure based on a core-shell structure was also observed by modern techniques of transmission electron microscopy [40].…”

Section: Resultssupporting

confidence: 76%

“…1 shows the associated slight shift of the diffraction peaks toward higher diffraction angles. These results are consistent with published works [41,42]. Figure 2 shows the Rietveld refinement of the neutron diffractogram from sample Co0 (without surface treatment).…”

Section: X-ray and Neutron Diffractograms-rietveld Refinementssupporting

confidence: 91%

“…Thus, for this nanosample, around 2.8 cobalt cations migrated from the octahedral sites to tetrahedral sites. This value of inversion degree is in good agreement with reported works [16,41,42] and differs from the value found in bulk standard materials due to reduction to the nanoscale and increase of the surface volume ratio in small particles, finite size, synthesis method, and surface effects. For the bare The values obtained for the isotropic displacement for A-and B-sites, and for the oxygen was 0.0028(2), 0.022(1), and 0.008 (1), which agrees with the results reported in literature [18].…”

Section: X-ray and Neutron Diffractograms-rietveld Refinementssupporting

confidence: 90%

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Local Structure Investigation of Core-Shell CoFe2O4@γ-Fe2O3 Nanoparticles

et al. 2020

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We investigate the local structure of nanoparticles based on cobalt ferrite core with and without a hydrothermal surface treatment of variable duration of time that promotes a coating shell by crossing information obtained from atomic absorption spectroscopy (AAS), X-ray powder diffraction (XRD), neutron powder diffraction (NPD), and X-ray absorption spectroscopy (XAS) measurements. Chemical titration results show that the surface layer thickness increases as the duration of the surface treatment increases. The cation distribution obtained by Rietveld refinement of NPD patterns allows splitting the core and shell structural parameters obtained from Rietveld refinement of XRD data of the samples well described in a core-shell model. We follow the local structural evolution with the surface treatment time analyzing both XANES and EXAFS regions of the absorption spectrum. As a result, we observe that the surface treatment is not energetically strong enough to provoke changes on the mean oxidation states of the cations in the spinel structure; indeed, the interatomic distances are similar to those found in bulk materials and the inversion degree remains the same after the surface treatment, in good accordance with the cation distribution obtained by Rietveld refinement of NPD data.

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Section: Resultssupporting

confidence: 76%

Section: X-ray and Neutron Diffractograms-rietveld Refinementssupporting

confidence: 91%

Section: X-ray and Neutron Diffractograms-rietveld Refinementssupporting

confidence: 90%

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Local Structure Investigation of Core-Shell CoFe2O4@γ-Fe2O3 Nanoparticles

et al. 2020

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“…The shell of maghemite gives the nanoparticles long-term stability preventing their dissolution in acidic medium. The structure and composition of these core–shell-type nanoparticles have been investigated in the literature [ 21 , 22 ].…”

Section: Methodsmentioning

confidence: 99%

L-Lysine-Coated Magnetic Core–Shell Nanoparticles for the Removal of Acetylsalicylic Acid from Aqueous Solutions

et al. 2023

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Nanotechnologies based on magnetic materials have been successfully used as efficient and reusable strategies to remove pharmaceutical residuals from water. This paper focuses on the fabrication, characterization, and application of ferrite-based magnetic nanoparticles functionalized with L-lysine as potential nanoadsorbents to remove acetylsalicylic acid (ASA) from water. The proposed nanomaterials are composed of highly magnetic and chemically stable core–shell nanoparticles covered with an adsorptive layer of L-lysine (CoFe2O4–g-Fe2O3–Lys). The nanoadsorbents were elaborated using the coprecipitation method in an alkaline medium, leading to nanoparticles with two different mean sizes (13.5 nm and 8.5 nm). The samples were characterized by XRD, TEM, FTIR, XPS, Zetametry, BET, and SQUID magnetometry. The influence of time, pH, and pollutant concentration was evaluated from batch studies using 1.33 g/L of the nanoadsorbents. The Freundlich isotherm best adjusted the adsorption data. The adsorption process exhibited a pseudo-second-order kinetic behavior. The optimal pH for adsorption was around 4-6, with a maximum adsorption capacity of 16.4 mg/g after 150 min of contact time. Regeneration tests also showed that the proposed nanomaterials are reusable. The set of results proved that the nanoadsorbents can be potentially used to remove ASA from water and provide relevant information for their application in large-scale designs.

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“…This shell endows the nanoparticles with long-term stability preventing their dissolution in acidic medium. The structure of these core@shell-type nanoparticles has been extensively studied elsewhere [33][34][35][36] .…”

Section: Sample Synthesismentioning

confidence: 99%

Reusable cysteine-ferrite-based magnetic nanopowders for removal of lead ions from water

et al. 2021

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Magnetic nanopowders were developed by functionalization of bimagnetic core@shell nanoparticles with cysteine (CoFe 2 O 4 @ɣ-Fe 2 O 3 @Cys), which present a core with high saturation magnetization (CoFe 2 O 4 ) combined with a shell with high long-term chemical stability (ɣ-Fe 2 O 3 ) and a sorptive L-cysteine layer. Samples of two different mean sizes were elaborated and characterized by XRD, TEM, FTIR, SER, zetametry and SQUID magnetometry. The adsorption of Pb(II) by the magnetic nanopowders was investigated as a function of pH, time, and pollutant concentration. The Langmuir model fitted well the adsorption data indicating monolayer adsorption, and a maximum adsorption capacity of 1.2 mg/g was found for pH 5. The kinetic data were well correlated to the pseudo-secondorder model and the best equilibrium time was 120 min. The adsorption mechanism mainly involves electrostatic interactions in pH 5-7 and hard-soft-acid-base interactions in low pH. Moreover, the nanoparticles were recovered and reused in readsorption experiments keeping a good removal efficiency.

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Local structure investigation of cobalt ferrite-based nanoparticles by synchrotron X-ray diffraction and absorption spectroscopy

Cited by 12 publications

References 36 publications

Local Structure Investigation of Core-Shell CoFe2O4@γ-Fe2O3 Nanoparticles

Local Structure Investigation of Core-Shell CoFe2O4@γ-Fe2O3 Nanoparticles

L-Lysine-Coated Magnetic Core–Shell Nanoparticles for the Removal of Acetylsalicylic Acid from Aqueous Solutions

Reusable cysteine-ferrite-based magnetic nanopowders for removal of lead ions from water

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