Synthesis, characterization and metal adsorption properties of the new ion exchanger polymer 3-n-propyl(4-methylpyridinium) silsesquioxane chloride

The preparation and anion exchange properties of 3-n-propyl(4-methylpyridinium) silsesquioxane chloride polymer are described. This new polymer was prepared by the sol-gel processing method and is designated as SiPic+Cl-. It is insoluble in water and showed an anion exchange capacity of 1.46x10(-3) mol g-1. The adsorption isotherms of ZnCl2, CdCl2 and HgCl2 were determined from aqueous solutions and the adsorption equilibria simulations fit the model of fixed bidentate centers with the absence of lateral interactions and energetic heterogeneity between them. The metal ions diffuse into the solid solution interface and are dominantly present as MCl2-(4) species for Zn(II), MCl(2-)4 and MCl-3 species for Cd(II) and MCl-3 species for Hg(II).     

Electron interactions and infrared spectra of para isomers of X(CF3Y)C6H4 compounds

IR spectra are reported for, in which X represents various polar substituents and Y a bridge with multiple bonds. There is a linear relation between the frequency of the v^E _C-F(H) degenerate vibration and Taft's induction constant * for the radical attached to the CF₃ group. Frequency v^E _C-F is also correlated with the _n, which shows that the conjugated system can transmit the electron effect of X to the CF₃ group. Compounds are compared as regards this transmission, and some features of the frequencies of the multiple bonds are elucidated.See[6, 7] for brief details of the spectra of some of the compounds.     

Electrical transport and magnetic ordering in R 2Ti3Ge4 (R=Dy, Ho and Er) compounds

New R ₂Ti₃Ge₄ (R=Dy, Ho and Er) intermetallic compounds have been synthesized and characterized by X-ray diffraction and low temperature ac magnetic susceptibility, electrical resistivity and thermoelectric power measurements were carried out. The compounds crystallize in the parent, Sm₅Ge₄-type orthorhombic structure (space group Pnma) and lanthanide contraction is observed as one moves along the rare-earth series. The changeover from paramagnetic to antiferromagnetic phase happens at low temperatures and the ordering temperature scales with the de Gennes factor. The electrical resistivity is metallic with a negative curvature above 100 K. Thermopower displays a weak maximum at temperatures less than 50 K signifying the possible phonon and magnon drag effects.     

A Test Method for Determining Total Metals with an Indicator Paper and Its Performance Characteristics

A test procedure is proposed for determining total metals (Cd, Co, Cu, Fe, Hg, Ni, and Zn) using irregular 1-(2-carboxyphenyl)-5-(4-methyl-6-methoxypyrimidine-2-yl)formazan-6-cellulose as an indicator paper. Regions of unreliable color reactions were determined for each of the metals and total metals present in equal concentrations. Statistical processing showed that the Weibull distribution function best describes the experimental results in the unreliable reaction regions. Unreliable reaction was observed in the range (3.6–4.4) × 10^–3 mg/L for the test procedure with preconcentration and in the range 1.7–3.4 mg/L for the procedure without preconcentration; the detection limits are 4.4 × 10^–3 and 3.4 mg/L, respectively. A synergetic effect of the component mixture was observed in determining total metals. The visual, reflectometric, and atomic absorption determination of total Co, Cu, Fe, Ni, and Zn in natural and tap water was studied; it was shown that the results of test determination agree well with the data of other methods.     

Elastic properties of the Ta–V system: bcc Ta0.33V0.67 and C15 TaV2

Resonant ultrasound spectroscopy was used to measure the elastic constants of bcc Ta_0.33V_0.67 over the temperature range 3.5–300?K; the results were compared to earlier measurements on C15 TaV₂. The temperature dependence of the polycrystalline shear modulus is completely different in the two phases; that of the bcc phase decreases with temperature whereas that of the C15 phases increases in an anomalous fashion. This difference is consistent with a model involving doubly-degenerate levels at the X point of the Brillouin zone in the C15 phase with the Fermi level lying near the doubly degenerate level. This model accounted for the unusual behaviour of the C15 phase. Debye temperatures were determined from the ultrasonic measurements: 295?K for the C15 phase and 315?K for the bcc phase.     

Surface functionalization of SBA-15 and a nonordered mesoporous silica with a 1,4-diazabicyclo[2.2.2]octane derivative: study of CuCl2 adsorption from ethanol solution

The equilibrium position of a spherical or prolate spheroidal particle resembling a needle floating at the interface between two immiscible fluids is discussed. A three-dimensional meniscus attached to an a priori unknown contact line at a specified contact angle is established around the particle, imparting to the particle a capillary force due to surface tension that is balanced by the buoyancy force and the particle weight. An accurate numerical solution for a floating sphere is obtained by solving a boundary-value problem, and the results are compared favorably with an approximate solution where the effect of the particle surface curvature is ignored and the elevation of the contact line is computed using an analytical solution for the meniscus attached to an inclined flat plate. The approximate formulation is applied locally around the nearly planar elliptical contact line of a prolate spheroid to derive a nonlinear algebraic equation governing the position of the particle center and the mean elevation of the contact line. The effect of the fluid and particle densities, contact angle, and capillary length is discussed, and the shape of the contact line is reconstructed and displayed from the local solution.     

Dissociation Constants of Silanol Groups of Silic Acids: Quantum Chemical Estimations

Dissociation constants of silanol groups on the silica surface are calculated with the DFT quantum chemical method using B3LYP and M06 functionals. Structural features of silanol fragments and the presence of hydrogen-bonded water clusters are shown to have significant effects on pK_a values of silanol groups. In particular, pK_a values are shown to vary widely depending on the features of the system of hydrogen bonds.     

Identification of water samples from different springs and rivers of Kharkiv: Comparison of methods for multivariate data analysis

The application of artificial neural networks for identifying water samples from different springs and rivers of Kharkiv based on the data about metal ions concentrations was studied. Using the river-water samples as an example, we demonstrated that the artificial neural networks enabled the correct identification of water samples, even if there were some gaps in the initial data. The procedure for determining the optimal number of neurons for synthesizing neural networks was proposed.     

Algorithm of object identification in qualitative chemical analysis based on fuzzy similarity criteria

An identification algorithm in qualitative chemical analysis is proposed based on the application of fuzzy (using the fuzzy set theory) similarity criteria. Examples of algorithm application to the identification of some objects are given; the stability of conclusions about the identification/nonidentification of objects to certain drawbacks is demonstrated.