Chelating tendencies in the rows of polymeric sorbents and their copper(II) and lead(II) complexes

The physicochemical properties of chelating polymer sorbents (CPSs), derivatives of poly(styrene-2-hydroxy-〈1-azo-1′〉-2′-hydroxybenzene), are studied with respect to copper and lead ions. The following sorption parameters are determined: the optimum acidity, temperature, and duration; the sorption capacity of the sorbent (SCS); and stability constants of polychelates. Quantitative correlations are found between the dissociation constants (pK′ _a) of the analytical functional group (AFG) of the sorbent, and the pH₅₀ of chelation of the tested metals; between p K′ _a and the stability of the complexes (logβ); and between pK′_a and the charge of the oxygen atom of the complexing group (z); these correlations are intended for use in elucidating the effect of the structural features and acid-base properties of the AFG on the chemisorption parameters of copper(II) and lead(II). These correlations predict the physical-chemical properties of sorbents and the sorption parameters of trace elements for preconcentrating and separating them from biological, natural, and technical objects     

The sorption of molybdenum by polymeric chelate-forming sorbents with the o-hydroxy?1-Azo-1′?o′-hydroxy functional group

The sorption of molybdenum by synthesized polymeric chelate-forming sorbents (PCSs) based on hydroxypolystyrene and a structural fragment with o-〈1-azo-1′〉o′-hydroxybenzene was studied. A mechanism of the sorption of molybdenum(VI) was suggested and substantiated. Qualitative correlations between the most important physicochemical parameters of the sorbent, sorption process, and sorbate (chelate) were established and described. The correlations can be used to quantitatively predict the physicochemical parameters of sorbents and their chelates for the purposes of synthesis, the use of PCSs for the concentration and isolation of elements, and physicochemical studies.     

Mössbauer study of the structure of amorphous invar and a two-level model of the expansion anomaly

The methods of Mössbauer spectroscopy and dilatometry are used to study the local atomic structure and thermal expansion of amorphous invar alloy Fe₈₃B₁₇. It is assumed that the alloy contains regions in which the local order corresponds to metastable orthorhombic and tetragonal phases of the composition Fe₃B. The quantitative ratio of these regions is determined from Mössbauer spectra and is found to be 1:3. A quantitative two-level model of volumetric striction is presented. It is proposed in the model that heating is accompanied by reversible relaxation of orthorhombic configurations of the Fe₃B type to tetragonal configurations, which in turn shortens the distance between iron atoms.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 12, pp. 43–46, December, 1989.     

Heteroadamantanes and their derivatives. 6. Synthesis and mass-spectrometric investigation of 5-mono- and 5,6-disubtituted 6-oxo-1,3-diazaadamantanes

The corresponding 5-mono- and 5,7-disubstituted 6-oxo-1,3-diazaadamantanes were obtained with high yields by the condensation of mono- and ,'-disubstituted acetones with hexamethylenetetramine in the presence of glacial acetic acid, and their structures were confirmed by IR and PMR spectra. The behavior of the compounds under electron impact was studied, and the main fragmentation paths of their molecules were determined.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1679–1685, December, 1985.     

An experimental and theoretical study of shock-wave propagation through reactive gases under conditions causing a transformation of the flow structure

Experimental observations of the transformation of the structure of shock waves entering the discharge gap of either a transverse or decaying glow discharge are presented. It is found that the total impulse of the shock wave pressure remains constant. A variation in the speed of sound, that is, the shock wave velocity, at which total dispersion of the wave occurs is found to be nonmonotonous across the discharge gap. The times over which the wave structure keeps changing after switching off the discharge have been more accurately determined. On the basis of the obtained experimental data and earlier results, a conclusion on the mechanism of this effect has been drawn. This mechanism is related to the dispersion of disturbances making up the wave structure in a relaxing medium (such as the glow discharge plasma). On the basis of a theory of this kind of dispersion, using the experimental data, and comparing energetic and temporal characteristics of the internal states of the plasma under study and the mode of sound disturbances (which according to the experiment, are responsible for the effect), we have succeeded in determining the O₂(a ¹Δ_g) state whose relaxation brings about this effect.     

Determination of uranium(VI) in natural waters after preconcentration on adsorbent containing m-aminophenol fragments

Sorption and complexing properties of a modified adsorbent based on a maleic anhydride-styrene copolymer towards uranium(VI) are studied and the main quantitative characteristics of the metal ion sorption are determined. An adsorbent containing m-aminophenol fragments is proposed for the selective sorption of uranium(VI) from solutions. The optimal sorption conditions have been found. The recovery of uranium(VI) under the optimal conditions exceeds 95%. A procedure of the sorption photometric determination of uranium(VI) in sea water is developed.     

40 years since the discovery of the arsenazo III reagent

The review was devoted to progress in the application of the well-known and widely used reagent Arsenazo III in analytical chemistry. Arsenazo III 2,7-bis[(2-arsonophenyl)azo]-1,8-dihydroxy-3,6-naphthalenedisulfonic acid was synthesized by S.B. Savvin in 1959     

Magnetic structure of the random system near the ferro-antiferromagnetic transition

The magnetic structure of the disordered alloy Fe₆₅Ni₂₈Mn₇ was investigated in the temperature 4.2–300 K by the methods: small angle scattering of neutrons, Mössbauer effect, magnetization, magnetic contribution to the thermal coefficient of the thermal expansion, and resistivity. All measurements show that long-range ferromagnetic order appears below T_c ? 160 K. At the same time for T ? 100 K, a dramatic change of magnetic state takes place which is interpreted as the freezing of “spin glass”. An increase of the magnetic contribution to the resistivity with decreasing temperature was also found. This increase was attributed to the existence of poor-bonded magnetic moments of the Kondo-type. A model of the magnetic ground state is proposed which includes the details of magnetic behavior such as long-range ferromagnetic order, spin glass, finite ferro-and antiferromagnetic clusters, and Kondo-type states. A magnetic phase diagram of the system Fe₆₅(Ni_1?xMn_x)₃₅ is also proposed.     

A physicochemical study of the sorption of lead: Correlations in a series of chelating polymer sorbents

The sorption properties of chelating polymer sorbents (CPSs), the derivatives of poly(styrene-2-oxy-azo-2′-oxybenzene), with respect to the lead ion are studied. The parameters of the sorption processes—optimum conditions of sorption (acidity, temperature, and time), the sorption capacities of sorbents, the possibility of desorption, and the stability constants of the chelated polymers—are determined. Quantitative correlations between p K′_OH of the functional analytical group (FAG) of the sorbent and σ _{o + p(p)} for ortho-and para-substituents, between p K′_OH and pH₅₀ for the formation of chelate complexes of lead, between p K′_OH and the stability of lead complexes (logβ), and between σ _{o + p(p)} and pH₅₀ for the formation of chelate complexes of lead are established with the aim of studying regularities of the influence of the structure and acid-base properties of FAGs on parameters of chemisorption of Pb²⁺. It is shown that the established correlations provide a means for quantitatively predicting physicochemical parameters of sorbents and the process of sorption of lead with the aim of targeted synthesis of CPSs and their use in the chemistry of polymer compounds and in the process of concentrating.