The structure of binary liquids. The Kirkwood-Buff theory of liquid mixtures,illustrated on the basis of the systems water/methanol,water/ethanol,and cyclohexane/2,3-dimethylbutane,as a link between thermodynamic data and x-ray and neutron scattering results

With the help of the Kirkwood-Buff theory of liquid mixtures it is demonstrated that there is a close relationship between, on the one hand, x-ray and neutron scattering intensities from liquid mixtures and, on the other hand, certain thermodynamic properties of the systems considered. This relationship can be utilized without having to specify the intermolecular interaction potential and without having to perform computer simulation calculations. In the present paper the Kirkwood-Buff theory is applied to liquid water and to the binary systems H₂O/MeOH, H₂O/EtOH, and cyclohexane/2,3-dimethyl-butane. On the basis of these examples it is explained that, from the thermodynamic quantities used, the detailed shape of the various molecular radial distribution functions cannot be established. However, in principle this information could well be obtained from the x-ray and neutron scattering intensities of the liquids that are being studied, provided an acceptable procedure could be found to isolate the different radial distribution functions. In this respect the information extracted from thermodynamic data would be essential since, in the first place, it provides a valuable way of normalization of the scattered intensity, and, in the second place, for multicomponent liquids it puts forward specific conditions to be satisfied by the various radial distribution functions.     

Self-diffusion in the isotropic and mesomorphic states of the lanthanide-containing system based on nonionic surfactant according to the NMR data

Molecular self-organization in a system based on lanthanum nitrate and the nonionogenic surfactant, viz., decaethylene glycol monododecyl ether, was studied in an aqueous solution and in the liquid-crystalline state. Molecular motion and phase transitions in the system were characterized by the high-resolution pulsed gradient spin-echo ¹H NMR method. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 488–494, March, 2008.     

Porous structure of rigid and swelling adsorbents according to pulsed NMR data on the mobility of adsorbed water and benzene molecules

Potentialities of pulsed NMR technique to estimate parameters of the porous structure of microporous adsorbents according to the data on nuclear magnetic relaxation and self-diffusion of adsorbed molecules are analyzed. Main attention was focused on the adsorbed systems studied by the adsorption and NMR techniques. Measurements of nuclear magnetic relaxation of adsorbed molecules make it possible to analyze the porous structure at the scale of pore sizes; data on self-diffusion, at the scale of different-porosity zones. Specific features of the translational mobility of water and benzene molecules with different mechanisms of adsorption in active carbons having relatively rigid structure and polymer adsorbents capable of swelling are discussed. In general, data obtained by the NMR technique agree with and supplement the results of adsorption measurements.     

Energetics of the interaction of water and other liquids with the surface of hydrophilic and hydrophobic sorbents according to data on the heats of wetting

Papers on the energetics of the interaction of various substances with the surface of hydrophilic and hydrophobic sorbents using the data from heats of wetting are reviewed. The thermodynamics of wetting is examined, and the important role of the heats of wetting for the production of quantitative data on the surface energy of solids is demonstrated. The uniqueness of the information on the physicochemical characteristics of the sorbents and catalysts obtained from the immersion wetting isotherms is emphasized, and up-to-date information on the extent, structure, and characteristics of the boundary layers of water is analyzed. It is shown that the calorimetric data serve as an experimental base for obtaining data on the structural ordering-disordering of the boundary layers of water. __________ Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 44, No. 1, pp. 1–23, January–February, 2008.     

Studies on the preparation of active oxygen-deficient copper ferrite and its application for hydrogen production through thermal chemical water splitting

Hydrogen generation through thermal chemical water splitting technology has recently received in- creasingly international interest in the nuclear hydrogen production field. Besides the main known sulfur-iodine (S-I) cycle developed by the General Atomics Company and the UT3 cycle (iron, calcium, and bromine) developed at the University of Tokyo, the thermal cycle based on metal oxide two-step water splitting methods is also receiving research and development attention worldwide. In this work, copper ferrite was prepared by the co-precipitation method and oxygen-deficient copper ferrite was synthesized through first and second calcination steps for the application of hydrogen production by a two-step water splitting process. The crystal structure, properties, chemical composition and δ were investigated in detail by utilizing X-ray diffraction (XRD), thermogravimetry (TG) and differential thermal analysis (DTA), atomic absorption spectrometer (AAS), ultraviolet spectrophotometry (UV), gas chro- matography (GC), and so on. The experimental two-step thermal chemical cycle reactor for hydrogen generation was designed and developed in this lab. The hydrogen generation process of water splitting through CuFe2O4-δ and the cycle performance of copper ferrite regeneration were firstly studied and discussed.     

Determination of carbofuran by the quenching effect on resonance light scattering and its application to water and vegetable samples

A new method for the determination of carbofuran (CF) with DNA by a resonance light scattering (RLS) technique was developed. The intensity of RLS (I _RLS) of DNA–HCl system was significantly quenched in presence of CF. A RLS peak at 315.6 nm was found, and the quenched intensity of RLS was proportional to the concentration of CF. The linear range of the calibration curve was ≈0.02–2.0 µg mL^?1 and the detection limit (S/N = 3) 7 ng mL^?1. The CF in river water, cucumbers and rice samples was determined. The recovery rates were in the range of 90.0–111.1, 95.0–106, 93.0–111.0%, respectively. The mechanism of the reaction between CF and DNA is also discussed.     

Effect of the orientation of coordinated water molecules on the electronic structure of trans halo-aquo complexes: application to TiCl2(H2O) 4 + and VCl2(H2O) 4 +

The X method has been utilized to calculate the electronic structure of trans-TiCl₂(H₂O) ₄ ⁺ and trans VCl₂(H₂O) ₄ ⁺ ions. Different conformations of coordinated water molecules have been considered. It has been found that the most stable configuration in both cases is the one with the plane of the water molecules parallel to the Cl-metal-Cl axis. The nature of the tetragonally distorted ground state has been found to depend on the orientation of the water molecules in these systems.