卷 89, 编号 3 (2016)
- 年: 2016
- 文章: 23
- URL: https://journals.rcsi.science/1070-4272/issue/view/13299
Inorganic Synthesis and Industrial Inorganic Chemistry
Characteristics optimization of activated alumina desiccants based on product of a centrifugal thermal activation of gibbsite
摘要
Activated alumina desiccants modified with NaOH and KOH were synthesized from the product of a centrifugal thermal activation of gibbsite, with the subsequent hydration in an acid or alkaline medium, and their properties were studied. It was shown that the modification makes it possible to raise the dynamic capacity of desiccants produced from pseudoboehmite by up to a factor of 2 via formation of new super-strong basic centers the concentration of which grows with increasing content of an alkaline oxide. A correlation was found between the total concentration of basic centers on the surface of the desiccants and their dynamic capacity in drying of both dry and humid air. Use of the modified desiccants with high static and dynamic capacity will make it possible to improve the drying efficiency.
Improvement of synthesis conditions of dispersed polymetallic Fe–Al–Mo systems in aqueous solutions
摘要
Kinetic dependences describing the processes occurring on aluminum microparticles in aqueous solutions containing iron and molybdenum ions were determined. It was shown that the samples obtained contain iron, molybdenum, and aluminum in the elementary state in the absence of an oxide phase.
Recovery of heavy metal ions with calcium peroxide microparticles
摘要
Sorption properties of micrometer calcium peroxide particles produced by the chemical reaction between calcium hydroxide and hydrogen peroxide were studied. The dependences of the sorption properties of CaO2 particles on temperature and acidity of the medium were used to find the optimal values of these parameters at which the sorption of metals is at the maximum. It was shown that CaO2 particles are nearly as good in sorption properties with hematite and goethite nanoparticles and possess antifungal properties exceeding the corresponding characteristics of sulfur and silver nanoparticles. The simplicity of the method used to obtain the product containing 73% CaO2, low expenditure due to the application of large-tonnage starting reagents, and its good sorption and antimicrobial properties make it possible to recommend this compound for purification of wastewater, natural water basins, and soil to remove heavy metal ions, with the simultaneous detoxication of these objects.
Study of thermal transformations of aluminum phosphate binder and composites on its basis with various fillers
摘要
Results are reported obtained in a study of the physicochemical processes occurring under heating in the temperature range 150–1100°C of an aluminum phosphate binder and composites on its basis with various fillers (SiO2, Al2O3, BN, and TiO2 nanoparticles) with the use of an X-ray diffraction analysis.
Extraction of contaminant metals from dumped metacolloid ores in order to reduce their hazardousness
摘要
Problems of human and environmental protection from discharges formed in out-of-balance ores dumped from nonferrous metallurgy were considered. To the most hazardous dumps belong those of metacolloid ores, discharges from which are contaminated with copper, zinc, iron, and also indium and cadmium. It was found that the most effective way to preclude the contamination is by using heap leaching of contaminant metals from ores in the chemical reclamation of the dumps. Mathematical dependences of the leaching rate of easily soluble compounds of metals (copper, zinc, indium, and cadmium) from metacolloid ores on the main technological factors of the process: sulfuric acid concentration, ore spraying density, and oxidation interval between sprayings were determined, the optimal process modes were found, and the cost-efficient production of metals in reclamation of dumps of this kind to a state in which they hardly contaminate the environment was calculated.
Sorption and Ion Exchange Processes
Activated carbons of varied nature in recovery of gold
摘要
Morphology and structure of activated carbons produced from a wide variety of carbon-containing vegetable and mineral raw materials were studied and their physicochemical characteristics were determined. The sorption of gold from industrial solutions with various pH values with activated carbons based on birch wood, coconut shells, and even shungite was examined. Results obtained in desorption of gold from activated carbons with a NaOH solution are presented.
Effect of the composition of the medium and electroflotation processing parameters on extraction efficiency of chromium(III) dispersed phase from aqueous solutions
摘要
Influence exerted by the composition of the medium (solution pH, ionic composition, presence of flocculants and surfactants), physicochemical properties of the dispersed phase (particle size, electrokinetic potential), and technological parameters of the electroflotation process (volume current density, magnetic treatment, solution temperature) on the efficiency of the electroflotation extraction of poorly soluble chromium(III) compounds from aqueous solutions was studied. It was shown that the extraction efficiency directly depends on the composition of the medium, which determines the physicochemical properties of poorly soluble chromium(III) compounds, and on the size of particles and their minimum surface charge. The optimal technological parameters of the electroflotation process are suggested.
Sol-gel synthesis and sorption properties of calcium monoaluminate
摘要
Method for synthesis of calcium aluminate and sorbents based on this compound was developed on its basis of the sol-gel technology. The method makes it possible to obtain the target product with specific surface areas in the range from 7 to 120 m2 g–1. The compounds obtained were characterized by scanning electron microscopy, X-ray phase analysis, and X-ray fluorescence microanalysis. It was found that the main phase of the sorbents is rhombohedral calcium monoaluminate CaAl2O4. The method of Hammett indicator adsorption was used to determine the content of active centers on the surface of the sorbents and the distribution of these centers over ionization constants. It was shown that the surface characteristics of the sorbents depend on their synthesis method. The retention parameters, polarities, and thermodynamic characteristics were determined for organic compounds of various classes. The possibility of using calcium aluminate modified with sodium chloride for gas-chromatographic separation of aliphatic and aromatic hydrocarbons and carbonyl compounds was demonstrated.
Synthesis of highly porous zinc–carbon composites based on modified pine wood
摘要
Highly porous materials containing zinc oxide were prepared form modified pine wood. The growth dynamics of zinc oxide microcrystallites in the course of carbonization of pine sawdust mixed with ZnCl2 was studied. The hexagonal wurtzite-type ZnO phase is formed at 400°С and is broken down at approximately 800°С. The synthesized composite material has a high specific surface area, up to 1900 m2 g–1. The relationships of the porous structure formation in the composite in relation to the temperature and subsequent treatment with water were revealed. Opening of the porous structure of the composite in the course of carbonization of modified pine sawdust is associated with the formation of crystal-like phases of carbon and ZnO.
Processes Using Various Catalyst Systems
Optimization of process parameters for preparing a solid catalyst for bisphenol synthesis
摘要
The results of optimization of the process parameters for preparing high-performance heterogeneous catalysts for bisphenol synthesis show that the performance of the solid acid catalyst is determined by its exchange capacity, acidity, pore structure, and specific surface area. Optimum process parameters for preparing highly active solid acid catalysts were revealed.
New composite catalysts for the synthesis of acetonitrile from ethanol and ammonia, prepared using calcium aluminates (Talyum)
摘要
Experiments on direct synthesis of acetonitrile from ethanol, ammonia, and hydrogen at 513–573 K in the presence of new Cu-, Cu–Zn–(Zr)-, and Cu–Mg-containing composite catalysts prepared using calcium aluminates (Talyum, technical-grade calcium aluminate) were performed The following results were reached: ethanol conversion 96.0–99.0%, selectivity with respect to acetonitrile 99.0%, and acetonitrile output exceeding the reported level by a factor of 1.2–1.4. The new technology can be implemented in industry.
Improvement of a process for preparing peracetic acid by the reaction of acetic acid with hydrogen peroxide in aqueous solutions, catalyzed by ion-exchange resins
摘要
The effect of Amberlyst 15Dry™ cation-exchange resin on the reaction of peracetic acid formation from acetic acid and hydrogen peroxide in aqueous solution was studied. The pathways of available oxygen consumption were determined. The noncatalytic synthesis is accompanied by spontaneous decomposition of the peracid formed, which sharply decelerates on introducing Amberlyst 15Dry catalyst into the reaction mixture. Comparison of the kinetic relationships of the processes occurring in batch and flow-through reactors shows that in the latter case the process is characterized by diffusion hindrance. A kinetic model of the process with the parameters ensuring adequate mathematical description of the data obtained was suggested.
Macromolecular Compounds and Polymeric Materials
Anticorrosion activity of aniline–aniline-2-sulfonic acid copolymers on the steel surface
摘要
The structure and barrier properties of layers formed on the interface of steel with aniline–orthanilic acid copolymers of different compositions were determined. The structure of the protective system ensuring the best anticorrosion properties was found.
Copolymers of betulin esters and silver nanocomposites based on them
摘要
New biologically active silver nanocomposites based on the copolymer of lup-20(29)-ene-3,28-diol 28-O-vinylbenzoate with N-vinylpyrrolidone were prepared by the borohydride method. The formation of spherical nanoparticles with a mean diameter of 67 nm was confirmed by scanning electron microscopy. The synthesized copolymers and silver nanocomposites exhibit cytotoxic activity and show promise for the development of new materials for medical purposes.
Preparation of magnetite nanoparticles modified with poly(о-phenylenediamine) and their use as drug carriers
摘要
A procedure was suggested for preparing nanoparticles consisting of magnetite and poly(o-phenylenediamine) by combining the hydrolysis of a mixture of iron(II) and (III) sulfates with oxidative polymerization of o-phenylenediamine. These nanoparticles efficiently bind phenylalanine, thyrosine, tryptophan, and doxorubicin in aqueous solution.
Effect of mechanical activation on characteristics of electrodes based on fluorinated carbon nanotubes
摘要
A procedure was developed for fabricating cathodes based on fluorinated carbon nanotubes for primary lithium current sources. The procedure allows reaching significantly higher levels of the discharging potential and capacity due to better homogenization and compaction of the electrode active mass.
Utilization of cellulose nitrate waste
摘要
A two-step procedure for utilization of cellulose nitrate waste accumulated at industrial enterprises of the Russian Federation was suggested and experimentally checked. The procedure involves hydrolysis of cellulose nitrate in alkaline medium and incineration of hydrolysis products. The best reagents for complete hydrolysis of cellulose nitrate are aqueous solutions of sodium hydroxide and sodium carbonate. As demonstrated by thermal analysis and thermodynamic calculations, incineration of cellulose nitrate base hydrolysis products can be performed without using hydrocarbon fuel.
Atomic concentration of hydrogen in tetra- and hexaamine heteroligand chromium(III) complexes with cyclic tetraamines
摘要
Based on the revealed dependence of the atomic concentration of hydrogen (NH) on the composition and structure of tetra- and hexaamine heteroligand chromium(III) complexes with cyclic tetraamines, routes to new materials with high NH for preparing effective composites for protection from neutron radiation were suggested.
Various Technological Processes
Preparation of hybrid ion exchanger based on acrylamide for sorption of some toxic metal ions from aqueous waste solutions
摘要
Crystalline phases of polyacrylamide titanium tungstophosphate composite material has been synthesized via sol–gel method. The properties of its were determined using different technique. The ion-exchange capacities of the hybrid material for Cs+, Co2+ and Eu3+ ions it was found that 6.22, 2.76 and 1.38 mequiv. g–1 respectively. The material was found that highly selective for Eu3+ and the selectivity sequence for sorption of Cs+, Co2+ and Eu3+ ions on polyacrylamide titanium tungstophosphate was found that; Eu3+ > Cs+ > Co2+. Thermodynamic parameters have been calculated for the studied ions showing that the overall adsorption process is spontaneous and endothermic. The experimental isotherm data were analyzed using the Langmuir and Freundlich models.
Recent developments on the modification of graphite electrodes with nanoparticles
摘要
The surface structure of common graphite electrodes are suitable for electrochemical detection of various analytes due to their favorable properties such as good conductivity and resistance to environmental and chemical hazards. Also this material is cheap and available. Modifying the surface of electrode improves their ability for various determinations. Modifying graphite electrodes with nanoparticles has attracted lots of attention due to their unique characteristics. In this article we review applications of modified graphite electrodes with nanomaterials.
Thermodynamic and adsorption behavior of N2O4 schiff base as a corrosion inhibitor for API-5L-X65 steel in HCl solution
摘要
The inhibition ability of N,N′-bis(2,4-dihydroxyacetophenone)-1,3-propandiimine (DHAPP) as a schiff base against the corrosion of API-5L-X65 in 1 M HCl solution was evaluated by polarization, electrochemical impedance spectroscopy, and scanning electron microscopy. Polarization studies indicated that DHAPP retards both the cathodic and anodic reactions through chemical adsorption and blocking the active corrosion sites. The adsorption of this compound obeyed the Langmuir adsorption isotherm. The inhibition efficiency increased with inhibitor concentration and decreased with increasing temperature. EIS data analysed to equivalent circuit model showed that as the inhibitor concentration increased the charge transfer resistance of steel increased whilst double layer capacitance decreased. Kinetic and thermodynamic parameters such as activation energy, enthalpy, entropy, and Gibbs free energy of activation and adsorption were calculated. Gibbs free energy indicated that adsorption occurred through physical and spontaneous process. Scanning electron microscopy was used to study the steel surface with and without inhibitor.
Synthesis and fluorescence study of the grafted salicylidene Schiff base onto SBA-15 mesoporous silica for detecting Zn2+ traces in aqueous medium
摘要
A selective fluorescent chemosensor was prepared by anchoring pyridine-2-carbaldehyde Schiff base ligand onto mesochannels of organically modified SBA-15 mesoporous silica. The resulting organic-inorganic hybrid mesoporous chemosensor was characterized by X-ray diffraction, Fourier transform IR spectroscopy, transmission electron microscopy, UV-visible diffuse reflectance spectra, and photoluminescence spectra. All the results support the idea that successive attachment of the ligand moiety onto one-pot-modified mesoporous scaffold has not altered its basic hexagonally arranged structure. Upon introducing trace amounts of zinc ions into aqueous solution, remarkable enhancement in the fluorescence was observed.
Experimental and theoretical study of some N-pyridinium salt derivatives as corrosion inhibitors for mild-steel in acidic media
摘要
N-pyridinium salt derivatives (1–5) were prepared and investigated as corrosion inhibitors for mild steel in 1 M H2SO4 solution at 30°C for 24 h. The corrosion inhibiting action was studied using weight loss measurements. The results demonstrated that the corrosion rate decreases, inhibition efficiencies increase, and surface coverage degree increases with increasing inhibitor concentration. Inhibition efficiencies for prepared N-pyridinium salt derivatives have highest inhibiting efficiency for even low concentration. The values of ΔGads° showed physisorption effect for all prepared compounds. Molecular modeling systems were achieved for suggested inhibitors 1–5. Theoretical calculations could be used as a useful tool to obtain information for explaining the mechanism and nature of interaction between the metal surface and the organic molecule as a corrosion inhibitor.