Vol 52, No 2 (2016)

A semiempirical method based on a generalized potential of intermolecular interactions (6, n) was developed to describe adsorption-stimulated deformation of microporous adsorbents. The calculations have been carried out for such adsorption systems as “microporous carbon adsorbent—methane” and “zeolite—NaX—Xe” in the temperature interval from 178 up to 393 K and at pressures ranging from 1 Pa to 6 MPa. The equations agreed qualitatively with experimental data.

Accumulation of electrolytic hydrogen in alkaline medium (5 M KOH) by multiwall carbon nanotubes (MWCNTs) 20–60 nm in inner diameter and 2 μm in length obtained by catalytic pyrolysis of propane/butane mixture has been studied by means of the electrochemical diffusion technique, cyclic voltammetry, and impedance spectroscopy. MWCNTs were applied on a steel membrane and were encapsulated by a 10-nm electrolytic nickel layer. Cyclic voltammograms were recorded in the range of potentials from −1.2 to +0.2 V and contained a current peak in the cathode region corresponding to hydrogen absorption by nanotubes at −0.9 V and current peak in the anode region corresponding to oxidation of absorbed hydrogen at −0.6 V. Hydrogen storage capacity of MWCNTs varies from 4.6 to 6.5% depending on the amount of nanotubes according to electrochemical diffusion data. The electrochemical impedance data correlate with the results of the above methods.

The effect of selective color reflection enhancement from a double metalized nanoporous anodic alumina (NAA) film surface under proper conditions of electrochemical and chemical metal (Cu—Ag, Cu—Au) deposition has been observed. Selective coloration of the NAA films with high index of the reflection and wide range of the color tones was achieved. The additional chemical deposition of the noble metal leads to the enhancement of the selective reflection ability and the interference contrast of the reflected light. The distribution of the chemically deposited silver nanoparticles on the top surface of electrochemically copper metalized pores of anodized aluminum has been shown by the electron microscopy method. The optical reflection spectra at different angles (10°-85°) of metalized NAA film have been measured, and the effective index of refraction (n ≈ 1.6) and film thickness have been calculated. The effect of the reflected light interference contrast enhancement has been explained as being a result of the more effective separation of the two reflecting surfaces air/Al₂O₃ in the structure of the film similar to a Fabry-Pérot interferometer.

In this paper the microstructure and tribological behavior of Zn—SnO₂ (Zn—Sn) alloys produced through chloride and sulphates co-deposition is presented for comparison. 7.0 wt % SnO₂ was added to Zn bath and deposited at 0.3 V. The interfacial effect and microchemistry of the fabricated composite was studied by optical microscope, X-ray diffraction (XRD), scanning electron microscope (SEM) equipped with energy disperse spectrum (EDS). The tribological behavior of the metal composites with SnO₂ particles as reinforcement was studied using reciprocating sliding tester. The scanning electron microscopy (SEM) and atomic force microscope (AFM) of the composite surfaces indicates that there is good interfacial interaction between the alloy formulated matrixes made from the two baths and the substrate. Reasonable uniform distribution of Sn metal phase particulates is shown for both coating alloy. Increases in hardness and wear resistance are attributed to the uniform and coherent precipitation in the metal interface especially for Zn—7Sn—S—0.3V. In general, 7 wt % Sn additions to the bath showed more hastening to improved surface properties and better mechanical characteristics.

In this study, the effect of electrophoretic voltage changes on Ni—Al₂O₃ nano-composite coating via two step process electrophoretic, and electrochemically on 1100 Al substrate on morphology, corrosion and wear behaviour were studied. In the first step of deposition for determining the optimum amount of Teri Ethanol Amin activator in electrophoretic suspension Transmission Electron Microscopy (TEM) was used. The amount of alumina particles, Nickel ions in the coating and morphology were studied by Energy-dispersive X-ray spectroscopy (EDX) and Field-Emission Electron Microscopy (FESEM). Nanoparticles distribute more homogenous in deposit within using 40 V voltage. Corrosion behaviour of coating was investigated by polarization technique in 3.5 wt % NaCl which shows a decrease in corrosion current from 13.7 μA/cm² to 1.46 μA/cm² versus bare sample.

It is found that the highest value of the separation factor of the nitrogen—oxygen mixture is observed for zeolite activated in the presence of 2 vol % CO₂ in nitrogen. It is shown on the basis of IR studies that the formation of bicarbonate structures is most characteristic for this sample.

The possibility of obtaining dispersed Fe—Cr—Al polymetallic systems by the method of contact exchange in chloride-containing aqueous solutions is determined. It is shown that the obtained systems have a branched structure of pores and channels composing the openwork assembly, which is formed from nanosize nuclei conjugated with each other.

Composites of polymers with conjugated chain structures, polyaniline and polypyrrole, are used as sorbents for human and bird flu viruses. Sorption properties of the composites are compared to characteristics of the initial polymers. It is shown that polymer composites containing metallic silver nanoparticles possess sorption activity, similarly to their composites with polyethylene and the initial polyaniline and polypyrrole. The introduction of silver into polypyrrole resulted in an enhancement of the sorption activity as compared to that of the initial polymer. Nontoxic metal—polymer composites reduce considerably the concentrations of human flu viruses A(H1N1), A(H3N2), and B and bird flu virus A(H5N2) with different structures of surface virion proteins in aqueous media at a sorbent concentration of 10–20 mg/mL in the temperature range from +4 to 37°C.

Problems of multiplex test development for the detection of antibodies to a number of infectious agents in clinical blood samples using protein arrays are discussed. Experimental data on the evaluation of microstructure and adsorption properties of synthetic materials for protein chip substrate are presented. The synthetic paper Pentaprint PR-M480/09-07/8101-482D8 was recognized as the best of the studied materials for the production of protein arrays.

This article investigates into the structure, phase composition, mechanical properties, and breakage pattern of oxide films formed on the surface of Zr—1% Nb alloy after corrosion tests in autoclave in water, steam, and water with lithium. Oxidation in water with lithium promotes formation of oxide films with a thickness of more than 100 μm, and, after oxidation in water or steam, the thickness is 5–15 μm. Upon oxidation in water, oxide films are generated with laminar structure: in the substrate, the grains are extended with the thickness of ~80 nm, near film surface the grains are equiaxial with the diameter of ~30 nm. After holding of the specimens in steam the oxide films are comprised mainly extended grains with the thickness of ~95 nm with a minor amount of equiaxial grains, 10%, with a diameter of ~30 nm, after oxidation in water with lithium the mixture of equiaxial and weakly extended nanograins is observed in the film structure. Upon loading of specimens with the structure of equiaxial and weakly extended grains the oxide films are broken due to generation of transversal cracks propagating to basic metal. The oxide films with laminar structure oxidized in water are broken due to exfoliation along the interface between the layers of extended and equiaxial grains. Breakage of films with the structure of equiaxial and weakly extended grains starts at the stage of elastic deformation at a stress of 300 MPa. The highest breakage stresses of 1150 MPa are characteristic for alloy specimens oxidized in steam. Breakage of films with laminar structure after oxidation in water occurs at average stresses of 798 MPa. The cohesive/adhesive strengths of films oxidized in water and steam are nearly the same. In thick alloys, oxide films oxidized in water with lithium, substrate does not open even at loading of 100 N. According to data of Raman spectroscopy, oxide film is mainly comprised of monoclinic phase of zirconium oxide; however, after oxidation in steam at the metal—film interface, a barrier layer of tetragonal phase of zirconium dioxide has been detected that prevents accelerated oxidation.

The corrosion inhibition of AZ91D magnesium alloy in 0.01 M H₂SO₄ by a Schiff base compound was investigated using Potentiodynamic polarization, Electrochemical Impedance Spectroscopy and Electrochemical Noise methods. It is found that the Schiff base acts as mixed-type inhibitor and the inhibition efficiency increases with concentration. Electrochemical impedance spectroscopy results showed that the Schiff base acts by adsorption at the metal/solution interface. Shot noise analysis showed that the inhibitor addition decreases the number of charge transfer events instead of the value of charge transfer at each electrochemical corrosion event. The corrosion inhibition effect was approved by suitable surface analysis.

3-(4-Iodophenyl)-2-imino-2,3-dihydrobenzo[d]oxazol-5-yl 4-methylbenzenesulfonate (4-IPhOXTs) was synthesized and its inhibiting action on the corrosion of Aluminum 1005 in sulfuric acid was investigated by means of potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The results of the investigation show that this compound has excellent inhibiting properties for Al corrosion in sulfuric acid. Inhibition efficiency increases with increase in the concentration of the inhibitor. The adsorption of 4-IPhOXTs onto the Al surface followed the Langmuir adsorption model with the free energy of adsorption ΔG_ads⁰ of‒9.18 kJ mol^–1. Quantum chemical calculations were employed to give further insight into the mechanism of inhibition action of 4-IPhOXTs.

The inhibitive action of leaves (LV), Latex (LX) and Fruit (FT) extracts of Calotrpis procera and Calotropis gigantea on mild steel corrosion in HCl, H₂SO₄ and mixture of solutions have been studied using mass loss and thermometric technique at different temperatures. The results indicate that the ethanolic extracts functioned as a good corrosion inhibitor in both environments and inhibition efficiency increased with extracts concentration. A mechanism of chemical adsorption of the plants components on the surface of the metal is proposed for the inhibition behavior. The inhibition efficiency increases up to 86.37%.