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18. ESR Analysis of Fe3+ and Mn2+ Complexes in Lignite Fulvic Acids.

Author

Zakharov, N. S., Sozinov, S. A., Zherebtsov, S. I., Malyshenko, N. V., and Shpakodraev, K. M.

Abstract

Samples of humic materials—humic acids and fulvic acids—derived from Tisul lignite (Kansk-Achinsk Basin) are investigated by ESR (electron spin resonance) spectroscopy. The concentration of free radicals declines in the following sequence: lignite, humic acids, fulvic acids. The proportion of aliphatic radicals increases in the same sequence. By simulation of the ESR spectra of the fulvic acids and comparison with the experimental spectra, natural complexes of fulvic acids with Fe3+ and Mn2+ ions are detected. By determining the splitting parameters in zero field (D and E), it is established that the complexes with Fe3+ have axial symmetry, with a complex multilevel structure. The internal coordination sphere of the complex consists of water molecules, whereas the external coordination sphere consists of oxygen-bearing fulvic acid groups. The calculated hyperfine structure constant of the experimental ESR spectra for the complexes with Mn2+ (79.7 G) is lower than the typical value for the octahedral Mn2+ complex [Mn(H2O)6]2+. That indicates partial replacement of the water molecules by oxygen-bearing functional groups of fulvic acids. [ABSTRACT FROM AUTHOR]

Published
2024
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38. Structural-Group Composition and Biological Activity of Humic and Lipid Substances of Brown Coals.

Author

Zherebtsov, S. I., Shpakodraev, K. M., Votolin, K. S., Malyshenko, N. V., and Ismagilov, Z. R.

Subjects
HUMUS, GAS chromatography/Mass spectrometry (GC-MS), HUMIC acid, HUMATES, LIGNITE, ELEMENTAL analysis, FRAGMENTED landscapes
Abstract

The samples of brown coal, bitumen and humic acids (HA) extracted from them are characterized by means of elemental and proximate analyses, FTIR, 13С NMR (CPMAS) spectroscopy and gas chromatography-mass spectrometry. The presence of biologically active substances is detected in the extracted bitumen samples. The biological activity of humic preparations in the form of sodium humates and the saponifiable component of the extracted bituminous resin is investigated depending on the structural-group parameters: aromaticity degree (far), the hydrophilichydrophobic parameter (fhh), and the parameter depicting the relationship between the aromatic and aliphatic fragments of the organic mass of HA (far/al). It is shown that O-alkylation of the organic mass of coal, followed by debituminizing, changes the structural-group composition of humic acids, causes an increase in the degree of aromaticity and leads to enhancement of the biological activity of HA. [ABSTRACT FROM AUTHOR]

Published
2022
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45. Sorption of pyridine-3-carboxylic acid by the Dowex-50 sulfonic cation-exchange resin in the NiII and CuII forms.

Author

Altshuler, H. N., Malyshenko, N. V., Nekrasov, V. N., and Altshuler, O. H.

Subjects
*SULFONIC acids, *TRANSITION metals, *NUCLEAR magnetic resonance spectroscopy, *ION exchange (Chemistry), *AQUEOUS solutions, *SORPTION
Abstract

The equilibrium distribution of components between aqueous solutions containing pyridine-3-carboxylic acid and Dowex-50 sulfonic cation-exchange resin in the NiII or CuII form was studied. The counterionic composition of the sulfonic cation-exchange resin was determined by solving a system of equations for the selectivity coefficients of the binary ion exchanges and the material balance equation. The experimental and calculated results for the sorption processes and the data of FT-IR spectroscopy and 13C CPMAS NMR spectroscopy of solid samples showed that pyridine-3-carboxylic acid in the Dowex-50 sulfonic cation-exchange resin is presented by the protonated [H2L]+ form or [CuHL]2+ cations. High distribution coefficients suggest that pyridine-3-carboxylic acid and metal cations (CuII, NiII) can be concentrated in the Dowex-50 sulfonic cation-exchange resin. The Dowex-50 sulfonic cation-exchange resin appears to be useful as a container for drugs based on pyridine-3-carboxylic acid and divalent transition metal cations, such as CuII and NiII. [ABSTRACT FROM AUTHOR]

Published
2021
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