The ESR and paramagnetic relaxation of Fe3+ in sulfonic acid ion-exchange resins

Vishnevskaya, G. P.; Volkov, B. A.; Plachinda, A. S.; Ramazanov, Rizvan; Reut, I. G.; Suzdalev, I. P.

doi:10.1007/bf00526167

Cited by 2 publications

(2 citation statements)

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“…The width of a large line is about 800 Oe for samples heated at ≤140°C and decreases to 400 Oe for samples heated at >140°C. The signals at g = 4.3 and 2.003 (wide line) are attributed to the Fe(III) ions in rhombic and octahedral surroundings, respectively 16. As is known, jarosite‐type compounds consist of octahedrons.…”

Section: Resultsmentioning

confidence: 94%

Nature of compounds formed in phase of strongly basic anion exchanger in contact with Fe₂(SO₄)₃ solutions

Gutsanu

Gafiichuk

Shofransky

et al. 2005

J of Applied Polymer Sci

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The thermochemical changes taking place in the phase of a Fe(III)‐containing strongly basic anion exchanger (AV‐17) are investigated by using Mössbauer, IR, and EPR spectroscopy. During the heating of Fe(III)‐containing resin in air up to 200°C, redox processes in the polymer phase take place. On boiling in water, the jarosite‐type compounds in the polymer are converted into higher dispersed β‐FeOOH particles. After sorption–boiling in water cycles in the polymer phase, relatively massive and magnetically ordered β‐FeOOH particles are formed. A portion of the β‐FeOOH particles remains in the highly dispersed superparamagnetic state distributed in the narrow pores of the exchanger. It is suggested that the Fe(III) ion sorption from Fe2(SO4)3 solutions by an exchanger takes place through the formation in the polymer phase of solid ultrafine particles of jarosite mineral‐type compounds. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 59–64, 2006

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Section: Resultsmentioning

confidence: 94%

Nature of compounds formed in phase of strongly basic anion exchanger in contact with Fe₂(SO₄)₃ solutions

Gutsanu

Gafiichuk

Shofransky

et al. 2005

J of Applied Polymer Sci

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“…Typically no Fe 3+ spectral line is observed downfield in either plant sample material. According to [8,17], this first of all may be associated with these ions predominantly existing in the form of hexaaqua complexes [Fe(H 2 O)6] 3+ with pseudo-octahedral symmetry of the environment, observed in the g ~ 2 region, compared with rhombically distorted complexes appearing at g ~ 4. Secondly, the signal from lowsymmetry centers in the g ~ 4 region may undergo considerable broadening due to the short relaxation times.…”

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confidence: 99%

Paramagnetic centers in oak and onion extracts

Bogushevich

Matveichuk

2009

J Appl Spectrosc

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We have used EPR to study oak bark, bulb onion peel, and their aqueous extracts. We have established that their paramagnetic properties are determined by at least four types of paramagnetic centers: semiquinone radicals, Fe 3+ ions, and two types of Mn 2+ ions. We have observed that metal ions are extracted by water from the plant raw material without any change in their original coordination environment. The aqueous extracts were subjected to oxidative processes: mild oxidation in the dried state, strong oxidation when stored as solutions. We have shown that when the solutions are stored, the oxidation reaction is catalyzed by the metal ions and is accompanied by formation of semiquinone radicals.Keywords: electron paramagnetic resonance spectroscopy, medicinal plants, extracts, phenols and polyphenols, antioxidant activity, semiquinone radicals, Fe 3+ and Mn 2+ ions.Introduction. We know [1, 2] that many medicinal plants and medicinal plant-based extracts have antioxidant activity. This is due to the presence of compounds in the phenol and polyphenol group, in particular flavonoids: hydroxy derivatives of flavanone, flavanonol, cathechins, flavone, and flavonol. The antioxidant activity of these substances is connected with their ability to enter into oxidation-reduction reactions with peroxide radicals, appearing in the body both during natural biochemical processes and under the influence of chemical and physical factors, in particular ultraviolet and ionizing radiation, and also in some diseases, especially cancers and atherosclerosis. Oxidation of phenols and polyphenols is accompanied by formation of low-activity, long-lived radicals of the semiquinone type, inhibiting the chain reaction of free-radical conversions [3,4]. In this case, the paramagnetic centers contained in the medicinal plant or its extract are certainly involved in the oxidation processes and make it possible to obtain important information about the mechanism for the antioxidant activity. However, the nature and conditions for the formation of these paramagnetic centers have not yet been sufficiently studied in most plant materials. The aim of this work was to study the paramagnetic properties of samples selected as model samples: oak bark, bulb onion peel, and their aqueous extracts.Experimental Procedure. We used dry samples of oak bark (from the botanicals producer Biotest NPK [Research and Production Cooperative], Grodno, Belarus) and bulb onion peel, ground and pulverized in an agate mortar to a powdered state, and also dry extracts of oak bark and bulb onion peel obtained from aqueous solutions. For extraction, a sample of the ground material weighing 10 g was placed in a round-bottom flask, 125 mL of distilled water was added, and it was boiled under reflux for 6 h. When extraction was finished, the solution was filtered and then the solvent was removed by evaporation on a water bath. The EPR spectra were recorded at T = 20

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The ESR and paramagnetic relaxation of Fe3+ in sulfonic acid ion-exchange resins

Cited by 2 publications

References 3 publications

Nature of compounds formed in phase of strongly basic anion exchanger in contact with Fe₂(SO₄)₃ solutions

Nature of compounds formed in phase of strongly basic anion exchanger in contact with Fe₂(SO₄)₃ solutions

Paramagnetic centers in oak and onion extracts

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The ESR and paramagnetic relaxation of Fe3+ in sulfonic acid ion-exchange resins

Cited by 2 publications

References 3 publications

Nature of compounds formed in phase of strongly basic anion exchanger in contact with Fe2(SO4)3 solutions

Nature of compounds formed in phase of strongly basic anion exchanger in contact with Fe2(SO4)3 solutions

Paramagnetic centers in oak and onion extracts

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Nature of compounds formed in phase of strongly basic anion exchanger in contact with Fe₂(SO₄)₃ solutions

Nature of compounds formed in phase of strongly basic anion exchanger in contact with Fe₂(SO₄)₃ solutions