Fe3 – δO4 Nanoparticles Synthesized in the Presence of Natural Polyelectrolytes

Pankratov, D. А.; Anuchina, M. M.; Спиридонов, Ф. М.; Krivtsov, G. G.

doi:10.1134/s1063774520030244

Cited by 21 publications

(15 citation statements)

References 12 publications

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“…A decrease of temperature results in an insignificant decrease of the intensity of the broad middle line of the U spectrum, while the intensity of paramagnetic part (asymmetric doublet and broad middle line) of the B spectrum is practically independent of temperature. It can be concluded that asymmetry of the resonance lines of the sextets at room temperature cannot be caused only by superparamagnetism (characteristic for nano-or highly dispersed iron particles) [66], but can be resulted from locally inhomogeneous environment of Fe atoms, at least in one phase present in the samples. On the other hand, the shoulders in the low-temperature spectrum of the U sample and the resonance lines out of the base line indicate superposition of the spectra of at least two magnetically ordered phases, one of which is responsible for distortion of the background line in the middle part of the spectrum at room temperature.…”

Section: Red Mud Samples Characterizationmentioning

confidence: 99%

Influence of Sodium Sulfate Addition on Iron Grain Growth during Carbothermic Roasting of Red Mud Samples with Different Basicity

Grudinsky

Zinoveev

Pankratov

et al. 2020

Metals

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Red mud is an iron-containing waste of alumina production with high alkalinity. A promising approach for its recycling is solid-phase carbothermic roasting in the presence of special additives followed by magnetic separation. The crucial factor of the separation of the obtained iron metallic particles from gangue is sufficiently large iron grains. This study focuses on the influence of Na2SO4 addition on iron grain growth during carbothermic roasting of two red mud samples with different (CaO + MgO)/(SiO2 + Al2O3) ratio of 0.46 and 1.21, respectively. Iron phase distribution in the red mud and roasted samples were investigated in detail by Mössbauer spectroscopy method. Based on thermodynamic calculations and results of multifactorial experiments, the optimal conditions for the roasting of the red mud samples with (CaO + MgO)/(SiO2 + Al2O3) ratio of 0.46 and 1.21 were duration of 180 min with the addition of 13.65% Na2SO4 at 1150 °C and 1350 °C followed by magnetic separation that led to 97% and 83.91% of iron recovery, as well as 51.6% and 83.7% of iron grade, respectively. The mechanism of sodium sulfate effect on iron grain growth was proposed. The results pointed out that Na2SO4 addition is unfavorable for the red mud carbothermic roasting compared with other alkaline sulfur-free additives.

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Section: Red Mud Samples Characterizationmentioning

confidence: 99%

Influence of Sodium Sulfate Addition on Iron Grain Growth during Carbothermic Roasting of Red Mud Samples with Different Basicity

Grudinsky

Zinoveev

Pankratov

et al. 2020

Metals

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“…Evidently, two other sextets (##3–4, Table 8 ) are related to γ-Fe 2 O 3 [ 76 , 77 , 78 ]. The reduced values of the magnetic splitting for the sextets at room temperature and the high value of the resonance line width with a strong temperature dependence suggest that this is a poorly ordered and very defective phase [ 79 ]. It could be assumed that the group of the sextets ##1–3 also includes the group of copper ferrite sextets with ultrafine parameters close to the indicated oxides—CuFe 2 O 4 [ 80 , 81 , 82 , 83 ] or substituted analogs of copper ferrite Cu 1-x A x Fe 2-y B y O 4 , where A and B are a substituent element in the oxidation state +2 or +3, respectively, for example, Zn +2 [ 84 , 85 , 86 ], Cd +2 [ 85 ], Al +3 [ 87 ], Ga +3 [ 86 ].…”

Section: Resultsmentioning

confidence: 99%

Comprehensive Study on the Mechanism of Sulfating Roasting of Zinc Plant Residue with Iron Sulfates

et al. 2021

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Zinc plant residue (ZPR) is a secondary material generated during hydrometallurgical zinc production that contains considerable contents of valuable elements such as Zn, Cu, Fe, Pb, Cd, Ag, In, Ga, Tl. Zinc, copper and accompanying elements in ZPR are in different minerals, mainly in the ferrites. A promising approach for recycling ZPR is the sulfating roasting using iron sulfates followed by water leaching. In this study, the composition of ZPR and the obtained products were thoroughly investigated by various methods including X-ray diffraction analysis (XRD), chemical phase analysis and Mössbauer spectroscopy. The effect of temperature, amount of iron sulfates and roasting time on the conversion of valuable metals into a water-soluble form was thermodynamically and experimentally studied both using pure ferrites and ZPR. Based on the results of time-resolved XRD analysis and synchronous thermal analysis (STA), a mechanism of the sulfation roasting was elucidated. The rate-controlling step of zinc and copper sulfation process during the ZPR roasting was estimated. The sulfating roasting at 600 °C during 180 min with the optimal Fe2(SO4)3∙9H2O addition followed by water leaching enables to recover 99% Zn and 80.3% Cu, while Fe, Pb, Ag, In, Ga retained almost fully in the residue.

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“…A slight decrease in the magnetite content in the samples containing humic acids (Fe 3 O 4 /HA) from ~82.7 % to ~79.2 % ( Table 1 ) can be associated with phenol and quinoid units in the HA structure [ 44 ]. Notably, the Fe 3 O 4 content in the Fe 3 O 4 /HA harsh oxidation sample was almost halved, assumingly due to the oxidation of magnetite NPs during mechanical treatment (harsh oxidation).…”

Section: Resultsmentioning

confidence: 99%

Effects of Humic Acids on the Ecotoxicity of Fe3O4 Nanoparticles and Fe-Ions: Impact of Oxidation and Aging

et al. 2020

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The magnetite nanoparticles (MNPs) are increasingly produced and studied for various environmental applications, yet the information on their ecotoxicity is scarce. We evaluated the ecotoxicity of MNPs (~7 nm) before and after the addition of humic acids (HAs). White mustard Sinapis alba and unicellular ciliates Paramecium caudatum were used as test species. The MNPs were modified by HAs and oxidized/aged under mild and harsh conditions. Bare MNPs proved not toxic to plants (96 h EC50 > 3300 mg/L) but the addition of HAs and mild oxidation increased their inhibitory effect, especially after harsh oxidation (96 h EC50 = 330 mg/L). Nevertheless, all these formulations could be ranked as ‘not harmful’ to S. alba (i.e., 96 h EC50 > 100 mg/L). The same tendency was observed for ciliates, but the respective EC50 values ranged from ‘harmful’ (24 h EC50 = 10–100 mg/L) to ‘very toxic’ (24h EC50 < 1 mg/L). The ecotoxicity of Fe-ions with and without the addition of HAs was evaluated in parallel: Fe (II) and Fe (III) ions were toxic to S. alba (96 h EC50 = 35 and 60 mg/L, respectively) and even more toxic to ciliates (24 h EC50 = 1 and 3 mg/L, respectively). Addition of the HAs to Fe-ions yielded the respective complexes not harmful to plants (96h EC50 > 100 mg/L) but toxic to ciliates (24h EC50 = 10–100 mg/L). These findings will be helpful for the understanding of the environmental fate and toxicity of iron-based NPs.

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Fe3 – δO4 Nanoparticles Synthesized in the Presence of Natural Polyelectrolytes

Cited by 21 publications

References 12 publications

Influence of Sodium Sulfate Addition on Iron Grain Growth during Carbothermic Roasting of Red Mud Samples with Different Basicity

Influence of Sodium Sulfate Addition on Iron Grain Growth during Carbothermic Roasting of Red Mud Samples with Different Basicity

Comprehensive Study on the Mechanism of Sulfating Roasting of Zinc Plant Residue with Iron Sulfates

Effects of Humic Acids on the Ecotoxicity of Fe3O4 Nanoparticles and Fe-Ions: Impact of Oxidation and Aging

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