Vol 50, No 4 (2016)

The state of the art in biomass conversion into liquid hydrocarbon biofuels aimed at obtaining synthesis gas and hydrogen for duel elements is analyzed. The most promising liquid hydrocarbon and oxygencontaining fuels for synthesis gas production are vegetable oils, diesel fuel, and biodiesel. Mathematical models are developed for the autothermal reforming, steam reforming and pre-reforming of biodiesel into synthesis gas and for the steam reforming of pre-reforming products integrated with the membrane separation of hydrogen. The results of calculations are verified against experimental data. The solution suggested here ensures 93.5% efficiency of the membrane separation of hydrogen from the reaction mixture and a theoretical hydrogen yield of 128 mol per kilogram of biodiesel.

The influence of the internal phase nature and electrolyte solution on the electroflotation extraction of the low-soluble copper compounds from the PCB production flushing water of the electronic technology was specified. Electroflotation activity decreases in the series Cu(OH)₂, CuCO₃, Cu₃PO₄, CuS. The influence of the surfactants (SAT) on the kinetics of the electroflotation process, on the particle size of the internal phase and electrokinetic potential has been studied. The change in the ξ-potential (for anion and cation SAT) and particle size (1.5–2 times) was specified for SAT. The electroflotation efficiency of Cu(OH)₂, Cu₃PO₄, and CuS under the optimum conditions is 98.5 and 90%, correspondingly.

Some results of studying the structured rolled ribbon-screw packing during the separation of hydrogen and oxygen isotopes via water distillation in columns with diameters of 60 and 120 mm and different heights of the packed bed have been presented. The results of studying the effect of process conditions on the ultimate throughput and the height equivalent to a theoretical plate have been considered. The coincidence of the mass-transfer characteristics in the separation of hydrogen and oxygen isotopes via vacuum water distillation has been shown.

In this paper, experimental investigation on convective drying of mixed municipal solid wastes was conducted. The aim of this study was to determine the effect of temperature, change in composition and particle size on the overall drying rate coefficient and mass transfer coefficient. Particle size of the samples was determined and mass losses recorded with time when the samples were dried using convective dryer. Mass losses were used to determine moisture content, drying rate coefficient and mass transfer coefficient. Experimental results showing the effect of temperature, changes in the composition of organic waste and particle size were presented.

An approach to determining the temperature profiles and effectiveness of gas and liquid cooling in the developed turbulent bubbling layer on trays in column apparatuses and film blocks of cooling towers has been considered. The approach is based on models of the flow structure for two-phase media. Diffusion and cell models with bulk heat and mass sources are used. The solutions of the system of equations of these models for various special cases of heat exchange in gas–liquid media on trays and in the packings of cooling towers have been given. The results of calculations and a comparison with experimental data have been demonstrated.

The catalytic effect of carbon nanotubes on epoxy polymer curing has been studied using the fractal method. The fractal dimension of epoxy microgels has been shown to be reduced by the interaction with the surface of carbon nanotubes. This effect is the only factor that contributes to the acceleration of epoxy crosslinking.

To improve the efficiency in of the separation and purification of gases by the method of gashydrate crystallization, the possibility of combining it with the membrane method has been studied. A mathematical model has been proposed for the hybrid-membrane gas-hydrate method. The application of membrane methods in gas-hydrate crystallization has been shown to prevent admixtures from concentration in a crystallizer and, thus, to considerably improve the efficiency of the gas separation and purification process. The proposed model of gas separation and purification was used to calculate the ratio of freon-12 purification from nitrogen and oxygen. The application of membrane gas separation with the purpose to prevent an admixture from concentration in a crystallizer was shown to increase the efficiency of freon-12 purification from nitrogen and oxygen via gas-hydrate crystallization by more than an order of magnitude at a high product takeoff (no less than 0.6).

Based on a study of the phase equilibria in cuts of a Mg(NO₃)₂–Ca(NO₃)₂–H₂O system at temperatures of 0 to–50°C, new deicers have been developed, including a liquid solution of magnesium and calcium nitrates and a solid composition of dehydrated nitrates. The ice-melting capacity of the agents under equilibrium conditions was determined. It was established that agents made of dehydrated magnesium and calcium nitrates interact with ice via heat release, which accelerates ice melting. The corrosion activity of liquid of a nitrate agent toward metals (in the collaboration with the All-Russian Institute of Aviation Materials) was determined. It was established that it can be significantly decreased at the introduction of a corrosion inhibitor. The possibility of synthesizing agents from natural mineral raw materials (dolomite, magnesite, and calcite) has been considered.

The review presents summary data on extracting agents and the application of sorption processes during the cycle of studies on the joint processing of calcium and silicon-containing raw materials on the production of calcium silicates and composite materials on their basis. It is found that, in processes of the production of synthetic calcium silicates from various types of calcium and silicon-containing raw materials, ionic and nonionic surfactants, including extractants, serve as structuring additives that hinder crystal growth and impede their agglomeration. The sorption properties of amorphous and crystalline nanopowders of calcium silicates and hydrosilicates synthesized from water-soluble materials are studied with respect to cations of base and rare metals. It has been found that the studied samples have high sorption capacity for cations of Eu3+, Pr³⁺, Tb³⁺, Er³⁺ and may be used as the basis for producing functional composite materials. The efficiency of applying the extraction-pyrolytic method has been shown to provide homogeneity and predetermined composition of the desired products, for the production of ceramic pigments and luminescent materials based on calcium silicates.

The influence of the type of solvent on the formability of acetate fibers by free-surface electrospinning has been studied. Defect-free ultrafine acetate fibers were produced using an acetic acid–formic acid binary solvent and polyethylene oxide added into the spinning solution. It has been established that using a one-layer paper filter with electrospun acetate fibers in a cigarette filter increases the efficiency of the filtration of tars and nicotine by 2.2–2.4 times.

In this work, we have suggested a new approach to fabricating fluorine-containing glass fibers based on the infiltration of glass-fiber filler by radiation-synthesized telomer solutions of tetrafluoroethylene. The radiation-chemical synthesis of tetrafluoroethylene telomers has been carried out in some solvents, their thermal stability has been studied, and the effectiveness of various telomers has been evaluated.

The results of studying the nonextractive oxidative demercaptanization of fuel oil derived from gascondensate in the presence of metal complex catalysts are presented in this work. The effect of the ratio of gaseous (air) and liquid (fuel oil) phases, catalyst concentration, time of contact, process temperature, and amount of total mercaptans on the degree of conversion of low molecular weight sulfur admixtures and quality of commercial products was evaluated.

The complex of physicochemical properties of high-silica zeolites of the MFI-type obtained using organic templates, including hexamethylenediamine, POD-oils, and pentaerythritol, has been investigated. It was shown that zeolites produced using different templates demonstrated different activity and selectivity in the process of converting the propane–butane fraction into aromatic hydrocarbons.

In the present study, the effect of deviations in the process has been determined during the process of the extraction processing of spent nuclear fuel (SNF) VVER-440 on RT-1 plant on the purification of uranium from ⁹⁹Tc, ¹²⁵Sb, ¹⁰⁶Ru, ¹³⁷Cs, ²²⁸Th, etc. The uranium decontamination factors during purification from these nuclides for both cycles of the Purex scheme of plant are calculated. It has been shown that, upon deviations in the process (the short-term shutdown of process, fluctuations of hydrodynamic mode, deposition of elements in the extractors, etc.), an increase in the uranium decontamination factors during purification from most unwanted nuclides is observed, except for technetium. However, it has been found that, at an increased inflow of Tc to the second extraction cycle, the purification of the final uranium product from this element may be insufficient.

Data on the mineral, phase, and elemental compositions of a zinc clinker as zinc production waste have been given and the possibility of hydrometallurgical processing using HCl solutions has been investigated. The kinetics of the clinker interacting with HCl solutions of 50–200 g/L in the temperature range of 50–90°C has been studied. The high efficiency of the muriatic acid for the decomposition of both the magnetic fraction and the general clinker sample with the 95–99% extraction of iron and nonferrous metal in solution and the more than 3.5-fold reduction in the clinker mass have been determined. The possibility of processing the filtrate extraction from the decomposition of the clinker by HCl using 100% tributyl phosphate as an extracting agent while obtaining oxide product containing >97% Fe suitable for producing iron-oxide pigment has been shown.

The distribution of chlorides and nitrates of lanthanides from aqueous solutions has been investigated in the absence of a salting out agent using a new binary extractant, methyl trioctyl ammonium dialkyl phosphinate compared with methyl trioctyl ammonium dialkyl phosphate. Isotherms of the extraction of lanthanides have ben obtained. The extraction stoichiometry of these metals in systems with binary extractants is determined. It has been found that, in the case of the extraction of nitrates of lanthanides by methyl trioctyl ammonium dialkyl phosphate and dialkyl phosphinate, extractable compounds of varying composition are formed. The extraction and separation of lanthanide chlorides by the conventional counter-current scheme and by the scheme based on the technology of free supported liquid membranes (FSLMs) have been experimentally and computationally investigated. It has been found that, when using the FSLM scheme, an increase in the degree of extraction and separation of lanthanides is observed.

Some examples of sorption-reagent materials and variants of their application in the practice of treating liquid radioactive waste have been considered. The data on the strontium sorption on samples of a sorption-reagent material under dynamic conditions at different degrees of dilution and different concentrations of seawater have been presented. These data demonstrate that the most efficient practical applications of sorption-reagent materials consist of decontaminating of seawater concentrates of strontium radionuclides. This task is stated during treatment of liquid radioactive waste (LRW) streams at the Fukushima-1 NPP (Japan), where reverse osmosis concentrates constitute the main problem of localization of the aftermath of the disaster that occurred in 2011.

The present review describes the state of the problem of extracting rare earth metals from secondary raw materials, such as high-coercivity magnets, nickel–metal hydride batteries (NiMH), and phosphors of coatings of fluorescent lamps. Methods for waste processing with mineral acids and other solvents, the removal of associated impurities from rare-earth components, separation, and deep purification (mainly by solvent extraction) have been considered. Data on the industrial applications of hydrometallurgical processes for rare earth metals recycling have been presented.

The effect of the pyrolysis temperature on luminescence characteristics of luminophores based on REE (rare-earth elements) compounds in the extraction-pyrolysis synthesis method has been investigated. The optimal synthesis conditions have been found, and the techniques for producing efficient nanosized luminophores based on REE oxides, oxysulfides, and phosphates have been developed.

The extraction mechanism has been considered and the crucial role of the dynamic interfacial layer has been noted. The microprocesses that take place in extraction systems and are associated with the Marangoni effect, the loss of hydrodynamic stability, partial dispersion, coalescence, flocculation, the Ostwald ripening of drops, chemical reactions, the emergence of a new phase, adsorption, coagulation, the formation of structures, and polymerization have been described. For LnCl₃–H₂O–diluent systems (heptane, toluene, tetrachloromethane), data on the shift in the boundaries of the observed transition region over time have been presented. The mechanism of the transfer of the substance in the transition region of the extraction system has been formulated.

A comparative analysis of the processes that occur at continuous and stepwise phase contact has been carried out. The free supported liquid membrane technique has been shown to be a step version of the conventional technique using supported liquid membranes.

The expediency of developing new sorption and extraction methods of separation of substances has been proved based on the differences in their interfacial distribution and the principles of improving the methods of performing processes of interphase distribution. The possibility of implementing the idea of twodimensional chromatography is considered based on the methodology chromatomembrane mass transfer process. The schemes of the continuous extraction-chromatographic liberation of gold, platinum (IV), and palladium (II) are described with simultaneous separation from the impurities of base metals.