Vol 52, No 6 (2016)

Adsorption properties of AU-4 microporous carbon adsorbent have been investigated for evaluating the effectiveness of methane accumulation over the temperature range from 178 to 360 K and at absolute pressures up to 25 MPa. It has been established that, within the pressure and temperature intervals under study, the maximum amount of methane achieved 160 nm³(СН₄)/m³. Efficient accumulation of methane in the AC-4 adsorbent over the entire temperature range was possible only within the interval of pressures from 1 to 7 MPa. When the “methane−AU-4” accumulation system was used at room temperature, the highest effect of adsorption accumulation may be achieved at pressures of 3–7 MPa. The differential and integral adsorption heats have been calculated and the degrees of overheating have been evaluated for methane storage systems with adsorbent.

The present study evaluates adsorption of hexavalent chromium ion (Cr(VI)) from contaminated solution on nano-porous anodic aluminum oxide (AAO). The AAO sorbent was characterized by field emission scanning electron microscope (FE-SEM) and Fourier transform infrared (FTIR) spectroscope. Effects of the solution pH, contact time, and AAO quantity on Cr(VI) adsorption were investigated. It was shown that Cr(VI) adsorption on AAO was strongly pH dependent and Cr(VI) removal increased by decreasing of the pH, Cr(VI) displays anion-type sorption behavior on the AAO sorbent. Chromium ion removal of 82% was obtained at presence of 0.05 g/L AAO, pH of 1, and contact time of 40 min in the solution.

Using high-performance liquid chromatography under conditions close to equilibrium, adsorption has been investigated for a series of aromatic compounds from water–acetonitrile, water–methanol, and water–isopropyl alcohol solutions on hyper-cross-linked polystyrene with the degree of cross linking of 500%. The principles of the effect of the nature of binary water–organic solvents on thermodynamic characteristics of adsorption of the studied substances on hyper-cross-linked polystyrene have been determined. The role of intermolecular interactions, which are realized in bulk solution and interface, in the adsorption of aromatic compounds from their maximum diluted water–organic solutions on hyper-cross-linked polystyrene has been discussed. The compensation effect upon adsorption on hyper-cross-linked polystyrene individually from water–acetonitrile solution and various water–alcohol solutions has been discovered. The existence of linear dependences between the differences of Gibbs energy upon adsorption from water–organic solutions on hyper-cross-linked polystyrene has been shown.

A number of new acidic phosphoryl podands with different substituents in the phosphoryl groups and different polyether chain structure are synthesized. They are used to obtain impregnation-type sorbents. A copolymer of styrene and divinyl benzene (LPS-500 grade) is used as a matrix for sorbent manufacturing. The effect of the structure and amount of supported phosphoryl podand, as well as of the concentration and nature of the acid in the initial solution of rare metals on extraction-chromatographic separation of La³⁺, Nd₃₊, Pm₃₊, and Sm₃₊ in the dynamic mode, is studied. It is found that the developed sorbents are superior with regard to efficiency of separation of these elements from weakly acidic media to the known counterparts synthesized on the basis of the conventionally used extractants: di(2-ethylhexyl)phosphoric acid and N,N,N′,N′-tetra-n-octyldiglycolamide. The possibility of practical application of the obtained sorbents for selective extraction and purification of promethium-147 from a number of associated rare-earth metals from technological solutions of PO Mayak is shown.

Conditions that allow obtaining stable aqueous dispersions based on conducting polymer, polyaniline, as a result of aniline polymerization in the solution of polymeric acid at its twofold excess were determined. The electrical and optical properties of polianiline obtained under these conditions remain invariable during at least 2 years due to the absence of aggregation of conducting polymer particles that are separated by macromolecules of polymeric acid. Data obtained by EPR spectroscopy, SEM, UV–visible spectroscopy, and IR spectroscopy prove these results.

Polymethylmethacrylate-based film composites containing small additives of fullerenes (up to 3 wt %) are obtained. The thermal behavior of the obtained materials is studied by DSC in the temperature range from 25 to 130°C. It is found that the character of the DSC curve depends on the composite composition. For films containing up to 0.1 wt % C₆₀, one glass transition temperature (T_g^soft) is observed, while in the case of films with a higher concentration of the filler, two glass transition temperatures (T_g^soft and T_g^solid) are observed. It is found that the dependence of T_g^soft value on the content of fullerenes is nonmonotonic with a minimum at 0.5 wt % of C60.

Copper- and zinc–polymer coatings were obtained via joint electrodeposition on a cathode of a water-soluble amine-containing polymer electrolyte and metals. The process of their formation, composition, structure, morphology, and properties were examined. The obtained coatings were found to possess high hardness and strength compared to pure polymer coatings if they have good elasticity.

Cu–Ni nanoparticles (NPs) thin films were prepared by Direct Current (DC) magnetron sputtering with Cu and Ni targets. The products were used as catalysts for Thermal CVD (TCVD) growing of carbon nanotubes (CNTs) from acetylene gas at 825°C. In order to characterize the nano catalysts, X-ray Diffraction (XRD) and Atomic Force Microscopy (AFM) and to study the synthesized CNTs Scanning Electron Microscopy (SEM) and Raman Spectroscopy were applied. A remarkable CNT grown on the sub-surface of catalyst layer compared to its top is deduced from SEM images. Despite the poor catalytic activity of the top-surface, these considerations led us to conclude more catalytic activity of the sub-surface.

This review is devoted to an analysis of plasma electrolytic saturation of steel and titanium alloys with light elements (nitrogen, carbon, and oxygen). These technologies have a number of advantages because of the high rates of processes and the low cost of equipment. Electrochemical aspects of the process, which include the formation of a gas–vapor shell, its composition, processes of anodic dissolution, and oxidation and adsorption of a saturating element on the surface processed, are considered. Data of investigations of the mechanism of the release and transport of nitrogen and carbon from the electrolyte into metal are given.

A study of the St37 steel rotating disc electrode/cooling water interface was carried out using an environmentally friendly inhibitor mixture including Tartaric acid (TaA) and Zinc sulfate. Electrochemical Impedance Spectroscopy measurements were performed in the absence and presence of inhibitor in cooling water under static conditions and at different rotation speeds. TaA did not show good inhibition efficiency at quiescent conditions. However, its performance became significantly better in the presence of Zn²⁺ ions. The increase in electrode rotation speed also enhanced the inhibition efficiency of TaA and its mixture with Zn²⁺ ions. The synergism between TaA and Zn²⁺ ions and the solution hydrodynamics promoted the formation and adsorption of Tartrate-Zn²⁺ complexes on the metal surface, leading to a highly protective layer formed on metal surface as a barrier against diffusion of corrosive ions. Analysis by scanning electron microscopy and energy dispersive X-ray analysis was presented for both the corroded and protected metal surfaces. Based on results, a mechanism for corrosion inhibition and the synergism between two components was proposed.

In the present work, sodium 4-[(4-formylbenzylidene) amino] benzoiate (4) was synthesized and its structure was confirmed using spectroscopic techniques. Prepared compound was successfully applied as a corrosion inhibitor for C1010 carbon steel in 3.5% NaCl solution at 25°C. Different electrochemical measurements such as linear polarization resistance (LPR), potentiodynamic polarization (PDP), and electrochemical impedance spectroscopy (EIS) were used to evaluate the suggested inhibitor (4). The results of different electrochemical measurements show that inhibition efficiencies obtained from EIS curves are in consistence with the results of potentiodynamic polarization and LPR measurements due to increase corrosion inhibition efficiency by increasing the concentration of organic inhibitor (4). Semi-empirical calculations with PM3 method were used to find relationship between molecular structure and inhibiting effect of suggested inhibitor (4).

In this study the failure analysis of an AA5083 mold material, used for curing rubber compounds, was carried out. The problem revealed itself as the formation of bubbles on the mold surface during curing process and caused quality problems in the final product. Preliminary microanalysis studies showed that there was an accumulation of both Mg and Cl in the bubble. Several samples were taken out from the inner/outer part of the mold material and examined using scanning electron microscope and energy dispersive X-ray spectrometer. It was concluded that (i) the contamination by Cl ions was due to the cutting oil used to open vent holes during mold cleaning, (ii) the outer part of mold material had finer α-Al grains whereas the inner part in contact with the compound had coarse grains due to the thermal effect of curing process, (iii) β-phase (Al₃Mg₂) formed at the grain boundaries after a sufficient exposure to temperatures above 50°C, (iv) the grain boundaries had Mg-rich phase showing anodic behavior, while the grains had Al-rich phase showing cathodic behavior, (v) the cracks initiated and propagated through the grain boundaries as stress corrosion cracking which resulted in the separation of grains and the accumulation of gases appeared as bubbles due to thermo-mechanical aging and effects of corrosive medium.