Sorption of humic substances on a weakly basic anion-exchange resin: Relationship with the adsorbate structure

Sorption of humic substances on a weakly basic anion-exchange resin: Relationship with the adsorbate structure. Pankratov D.A., Anuchina M.M., Borisova E.M., Volikov A.B., Konstantinov A.I., Perminova I.V. //Russian Journal of Physical Chemistry A. 2017. V.91. №6. P.1109-1115.

Adsorption of a broad range of humic substances (HS) of different origins and fractional compositions on a macroporous weakly basic anion-exchange resin is studied. It is found that the nature of the humic substances has a substantial effect on both the efficiency of sorption and the mechanism of interaction with the adsorbent. The dependence of the determined thermodynamic parameters of sorption on the humic substances origin, composition, and structure is shown for a broad range of humic substances. It is concluded that the results can be used to predict the sorption properties of weakly basic anion-exchange resins with respect to humic substances of known origin and structural group composition.

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Properties of Iron-Containing Nanohydroxyapatite- Based Composites

Properties of Iron-Containing Nanohydroxyapatite-Based Composites. Pankratov D.A., Dolzhenko V.D., Ovchenkov E.A., Anuchina M.M., Severin A.V. //Inorganic Materials. 2017. V.53. №1. P.89-98.

The paramagnetic properties of compounds resulting from the synthesis of nanohydroxyapatite in the presence of Fe(III) ions have been studied by electron paramagnetic resonance, Mössbauer spectroscopy, and magnetochemistry. Based on the obtained results on the mechanism of the reaction between an orthophosphoric acid solution and an aqueous calcium hydroxide suspension, we have found conditions for incorporating Fe(III) impurity ions into hydroxyapatite. We have studied samples differing in the sequence in which reagents were mixed and in hydroxyapatite crystallite formation conditions. It has been shown that, in all instances, the composition and properties of the iron-containing phases in the composites depend significantly on both synthesis and heat treatment conditions.

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New Platinum Superoxo Complex

New Platinum Superoxo Complex. Kiselev Yu.M., Pankratov D.A., Shundrin L.A., Kiseleva I.N. //Russian Journal of Inorganic Chemistry. 1996. V. 41. № 12. P. 1963-1966

Products of oxidation of Pt(IV) hexahydroxo complexes with ozone in alkali media have been studied with physicochemical methods (electron spectroscopy, EPR, and cyclic voltammetry). The oxidation product is pink at alkali concentration in solution higher than 5 mol/l. The pink complex represents previously undescribed platinum superoxo complex with a bridging O₂^- group.

Our previous study concerned the possibility of preparing platinum compounds in unusually high oxidation states from alka1ine solutions under the action of ozone. In that study, we detected a blue platinum superoxo complex of binuclear structure with the O₂^- bridging group. The bridge structure of this complex was supported by ESR, and the complex was show to form only at rather low alkalinity. At higher alkali concentrations (c_OH- > 5 mol/l), a similar reaction results in a pale pink complex containing oxidizer.

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Solid Platinum Superoxo Hydroxo Complex

Solid Platinum Superoxo Hydroxo Complex. Pankratov D.A., Komozin P.N., Kiselev Yu.M. //Russian Journal of Inorganic Chemistry. 2000. V. 45. № 10. P. 1555-1559

Solid samples isolated from solutions of a platinum superoxo hydroxo complex are studied by EPR and X-ray powder diffraction techniques. The short-lived superoxo complex is found to form upon dissolution of the solid samples in concentrated acids. Magnetic resonance parameters of the platinum superoxo complexes in the solid state and in acidic solutions are determined. The structures of the inner coordination sphere of the found superoxo complexes are discussed.

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