Vol 89, No 2 (2016)

Effect of Rolivsan MV-1 on the process of curing and pyrolysis of polycarbosilane PCS-M in argon and on the properties of the ceramic matrix being formed. Use of Rolivsan in polycarbosilane formulations provides effective curing of the latter to give network block-copolymers. Pyrolysis of the resulting precursors in the atmosphere of argon yields ceramic matrices, with the yield of these being 1.3–1.4 times that of the pyrolyzate of the starting components. A study of the elemental and phase composition demonstrated that the matrices belong to the class of amorphous ceramics of nonstoichiometric composition, which contain microcrystalline silicon carbide SiC. The ceramic obtained has a high thermo-oxidative stability (up to 1400°C) and changing the relative amounts of the starting oligomers enables a purposeful variation of its composition, temperature stability, and service characteristics of ceramic-matrix composite materials obtained on its basis by the “polymer technology.”

The kinetics of sulfuric acid breakdown of a mixture of beryl and bertrandite–phenakite–fluorite concentrates, activated by fusion with sodium carbonate, was studied. The apparent activation energy of the reaction of the granulated fusion cake with sulfuric acid was determined (E_app = 9.1 kJ mol^–1). This value of E_app is typical of diffusion-controlled processes and suggests that the process is controlled by the rate of diffusion of acid molecules to the reaction surface through the layer of the forming reaction products.

The thermodynamic properties of lead–sodium–antimony liquid alloys were determined by the emf method. The thermodynamic properties of the edge binary systems, sodium–lead, sodium–antimony, and lead–antimony, were analyzed. The possibility of approximately estimating the thermodynamic properties of the ternary system on the basis of data on the edge binary systems using the simplest geometric models was demonstrated. The sodium-containing alloys show significant negative deviations from the ideal behavior. All the data are given for 900 K.

Aqueous dispersions of polyaniline were synthesized in the presence of various surfactants. Polyvinyl alcohol and polymeric surfactants with various chain lengths of polyoxyethylene fragments served as stabilizers. It was shown that it is advisable to use polymeric surfactants with side polyoxyethylene fragments to improve the sedimentation stability of aqueous dispersions of polyaniline. It was found that the particle size distribution of aqueous dispersions depends on the composition of the stabilizer used. Raising the pH value of aqueous dispersions to 8 makes it possible to substantially raise the sedimentation stability. The effect of a surfactant used to stabilize the dispersed system on the electrokinetic potential was examined.

Selective recovery and concentration of platinum(IV) and palladium(II) from hydrochloric acid solutions of varied composition was studied using commercial reagents propiconazole and penconazole as extractants. The ranges of hydrochloric acid concentrations for effective extraction and highly selective separation of platinum metals from Al(III) and Ni(II) with propiconazole (toluene with 15 vol % n-decanol as deluent) and penconazole (chloroform) were determined. The conditions for 10-fold selective concentration of platinum metals with recovery of more than 99.9% of metal ions into the organic phase were found. The conditions for quantitative (>99%) stripping of platinum(IV) with a hydrochloric acid solution of thiourea and palladium(II) with ammonia solution were determined. The results obtained can be used for optimizing the modes of selective recovery of platinum(IV) and palladium(II) from hydrochloric acid solutions formed in leaching of alumina-supported platinum-rhenium, platinum-nickel, and palladium catalysts.

Coprecipitation followed by sintering were used to synthesize nanocomposite materials in the CoO–SnO₂ system under various conditions. The crystal structure, morphology, chemical and phase transformations of the materials were examined. The specific capacity of the materials was determined in their possible use as electrode materials for supercapacitors.

Turnover frequencies of catalytic systems based on nickel complexes with 1,4-diaza-1,3-butadiene (α-diimine) ligands in the reactions of styrene hydrogenation and ethylene polymerization were determined. Results are presented of a study by the electron paramagnetic resonance method and IR spectroscopy of 1,4-diaza-1,3-butadiene complexes of nickel(II) and anion radicals formed in the interaction of the starting components under the conditions of catalysis. It was shown that the paramagnetic Ni(I) complexes are precursors of complexes catalytically active in the hydrogenation and polymerization reactions.

Catalytic properties of the RhSe₂/Ga/H-ZSM-5 system formed upon thermal treatment of a mechanical mixture of rhodium selenochloride Rh₂Se₉Cl₆ and a gallium-containing zeolite Ga/H-ZSM-5 at 300–340°C in a flow of nitrogen were studied in the course of glycerol dehydration in the gas phase. It was shown that the promotion of Ga/H-ZSM-5 with rhodium selenide RhSe₂ makes higher the yield of the target product acrolein.

The time dependences of the elastic moduli and loss moduli of aqueous solutions of Alcoflood-254S carboxylated polyacrylamide, containing chromium(III) acetate as a cross-linking agent, were studied by oscillation rheometry in the temperature interval 50–80°?. The gel time increases with a decrease in the temperature, as well as in the concentration of the polymer and cross-linking agent. The elastic properties of hydrogels at the moment of the onset of their formation, characterizing the concentration of cross-links between the macromolecules, are due to the polymer concentration in the solution and are independent of the chromium(III) acetate concentration and temperature. Presumably, equal degree of conversion in the reaction between carboxylate groups of the polymer and chromium(III) ion, leading to cross-linking of macromolecules of carboxylated polyacrylamide, allows determination of the kinetic parameters of the gelation from data obtained by oscillation rheometry under nonisothermal conditions.

The conversion of black oil in hydrogen (hydroconversion) and nitrogen (pyrolysis) media was studied. The influence of the hydrogen pressure and temperature of the hydrotreating of black oil on the yield and properties of the resulting liquid hydrocarbons was examined. Hydrogen actively participates in the conversion of kerogen (major organic component of black oil), which leads to an increase in the conversion of the organic matter, to an increase in the yield of liquid hydrocarbon products, and to improvement of their quality, compared to pyrolysis. The highest conversion of organic carbon (91.7%) and the maximal yield of liquid hydrocarbons (30.7 wt %) were reached in a hydrogen medium at a pressure of 10.0 MPa and a temperature of 400°C.

Ultrafiltration membranes based on interpolyelectrolyte complexes of sulfonate-containing aromatic copolyamide, acrylonitrile–N,N-dimethyl-N,N-diallylammonium chloride copolymer, and poly-N,N-dimethyl-N,N-diallylammonium chloride were prepared. Their structure and surface electrical properties were studied. The correlation between the procedure for performing the interpolymer reaction, the degree of conversion, the composition of the resulting complex, and the membrane characteristics was revealed. The electrokinetic potential of the membrane specimens varies in the interval from–35.2 to +3.1 mV. The interpolymer compound composition, surface electrical properties of the membranes, and their activity in sorption of base and acid dyes correlate with each other. Therefore, it is appropriate to use these dyes as test systems for determining the nature and concentration of free ionic groups. The effect of the membrane preparation procedure on the charge distribution pattern on the membrane separation surface is considered.

Maleic acid, present in the effluent from organic intermediate producing industries, is an industrially important raw material. Its use in manufacture of alkyd and polyester resins, surface coatings, lubricant additives, plasticizers, co-polymers and agricultural chemicals, makes it necessary to explore for best possible techniques to recover it from aqueous solutions. The present work investigates the recovery of maleic acid from aqueous solution at ambient temperature. N–Methyl–n, n–dioctyloctan–1–ammonium chloride, (commercially known as Aliquat 336) is used as an extractant with three different diluents, belonging to different chemical classes: an aromatic hydrocarbon, a ketone, and an acetate. The chemical extraction results are reported in the terms of distribution coefficient, degree of extraction, and loading ratios. The results were modeled by mass action equilibria model as well as differential evolution technique. Differential evolution algorithm has been prepared. The model and experimental observations were compared and fairly good agreement was observed.

In this study, a novel temperature controlled molecularly imprinted membrane (Temp-Ctrl-MIM) made of chitosan and methyl methacrylate was fabricated with bovine serum albumin (BSA) as template molecule. The film was characterized by infrared spectroscopy (IR), X-ray diffraction (XRD), scanning electron microscopy (SEM) and the permeation experiment. The results revealed that the porous structure of the film was as similar as the BSA. Moreover, the membrane had advanced molecular imprinting capability to BSA comparing to pepsin and casein at any temperature and the film demonstrated an excellent ability to identify specific template molecule (BSA) at the synthesis temperature comparing to other temperatures.

In the paper, a novel hydroxy lauric imidazoline (HL-IM) was synthesized using lauric acid and ethylene diamine as raw materials. Methanol reaction method was introduced to prepare the hydroxy lauric imidazoline (HL-IM). According to the results of experiments, the optimum synthesis conditions of methanol reaction was determined through orthogonal experiment, which were: methyl laurate: ethylene diamine = 1: 1, sodium methoxide (0.75 wt %), reaction temperature 100°C, reaction time 2 h. The inhibition efficiency of HL-IM inhibitor was investigated in the condition of 5 wt % NaCl solutions saturated with CO₂ at 333.15 K for 72 h. With 150 mg L^–1 inhibitor dosage, the efficiency of inhibition reached 90.17% by weight loss method. Through film-forming property, foaming characteristic, and emulsification tendency test, it w a s shown that HL-IM had good water-solubility, a smaller emulsification tendency in 5 wt % NaCl solution, and a little foaming performance. Meanwhile, referring to the polarization curves tests, the synergistic effect of HL-IM with the potassium iodide, methylbutynol, and cetyltrimethyl ammonium bromide was studied.

Super absorbent polymers (SAPs) are of great significance in industry and personal care, etc. The study aims to introduce novel nanocomposite SAPs that are able to uptake very high water content while maintaining excellent strength. The polymers are synthesized by in situ polymerization with the presence of exfoliated montmorillonite (MMT) and trace amount of crosslinkers. SEM images show macroporous structures of these nanocomposites, while TEM images demonstrate excellent distribution of the MMT nanosheets in the polymer matrix. The effect of clay content on the equilibrium water uptake has been systematically investigated. More importantly, the highly swollen nanocomposite SAPs show very high tensile strength (up to 550 kPa), which is much higher than those reported in literature and used in the market. These SAPs with high water uptake and strength may find applications in agriculture and oil fields.

The liquid product of automobile tire pyrolysis and its fractions were studied. The amount of the liquid hydrocarbon fraction is 40–45% of the total weight of pyrolysis products. The hydrocarbon fraction is similar in its characteristics to low-sulfur heavy crude oil. Fractionation of the hydrocarbon fuel was performed. The maximal yield of the light distillation fraction is 39% (temperature interval 180–340°C). The extent to which the characteristics of the light fraction obtained meet the regulations was evaluated. The light fraction of hydrocarbon fuel produced by pyrolysis is recommended for use as a component of diesel motor fuel after additional purification.

Ho³⁺-doped bismuth(III) fluoride was suggested for upconversion of 2-μm laser radiation (1.9–2.1 µm) into visible emission. The process is possible owing to direct excitation of the ⁵I₇ level, followed by the excitation of the ⁵F₅ level with the emission threshold of 1.4 W.