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Cobalt ferrites, which have a spinel cubic structure, have been widely studied for many years. This is primarily due to the extremely wide range of their use, covering such areas of application as high-density magnetic recording, medicine (computed tomography, contrast agents of magnetic resonance imaging, targeted introduction of drugs and hyperthermia), electronic, telecommunication and space equipment, environmental technologies, gas sensors, supercapacitors, etc. The use of liquid-phase technologies for producing cobalt ferrites allows us to change the structure, composition and, as a result, the functional properties of a final product. The hydrophase method is widespread, including the step of coprecipitation of trivalent and divalent hydroxides with further heat treatment at high temperatures. Technologies that are more promising based on the codeposition of the iron(II) and cobalt(II) hydroxides. However, this process has not been sufficiently studied. In this work, using the thermodynamic calculations and cyclic voltammetry (CVA), we study the Fe2++–SO4 2++–Н2+О, Со2++–SO4 2++–Н2+О, Fe2++–Со2++–SO4 2++–Н2+О systems. Successive stages of the formation of hydroxocomplexes are established. Thermodynamic calculations show that the pH values for the deposition of hydroxides have similar values. The CVA data were obtained with a molar ratio n=[OH+ ]/[M2++]=1 in the Fe2++–Со2++–SO4 2++–Н2+О system. The course of the cathode sections of the curves changes sequentially for cycles 1–5 that indicates the degradation of the formed intermediate compounds. [ABSTRACT FROM AUTHOR]

The paper investigates the methods of surface treatment of cobalt-based alloys in order to improve their tribological properties, particularly - working in process. We propose to use the method of surface oxidation what eases the initial period of wear process. This creates a thin layer of oxides, which play the role of solid lubricant. Also at high temperature it separates friction surfaces and avoids their seizure. Laser-aided thermal cycling makes the matrix-filler bond stronger. The heating in a wide range of temperatures activates diffusion of matrix into the filler. Thermal cycling mode allows leaving behind carbides coagulation. At high temperature improved phases bonding will minimize carbides fallout. [ABSTRACT FROM AUTHOR]

The structural and adsorption properties of montmorillonite pillared with titanium and iron polyhydroxocomplexes are given in the paper. It was found that the composition of the polyhydroxocom plexes significantly affects the properties of the resultant materials. For studying the basic properties of the resultant materials, the X-ray phase analysis, the low-temperature nitrogen adsorption, and adsorption of the metal ions from aqueous solutions were used. The results of the X-ray phase analysis, with changes in the respective basal reflections, confirm the presence of iron and titanium polyhydroxocomplexes in the interlayer space of the mineral. Synthesized pillared minerals have a well-developed specific surface, micro- and mesoporosity, as confirmed by the low-temperature nitrogen adsorption. It was found that the pillared montmorillonite shows relatively high adsorption characteristics relatively to chromium and uranium ions. Adsorption on the pillared montmorillonite samples significantly depends on the pH solutions, adsorptive properties and the composition of the polyhydroxocomplexes, which were used for synthesizing adsorbents. The research results can be useful for developing and synthesizing new types of inorganic ion-exchange materials for extracting cations and anions of various inorganic toxicants from aqueous solutions. [ABSTRACT FROM AUTHOR]

This paper shows the influence of cationic surface-active agents (SAA) with a different structure of the hydrophobic chain on the modification of the surface structure of silicate mineral montmorillonite and adsorptive properties of the resultant sorbent for extracting ions of chromium (VI) and cobalt (II) from aqueous media. Macroelectrophoresis and sorption methods for designating the selected samples were used in the research. It was proved that increasing the amount of surfactants added to a dispersed system, long-chain surfactants tend to form more stable hemicellar structure on the clay surface and more fully recharge it. It was found that the increasing the number of the hydrocarbon chain links from 1 to 16 the physicochemical characteristics of the obtained materials are changed dramatically: the adsorption of chromium increases to about 45 mg/g, while the adsorption of cobalt falls to zero in the full range of the surface-active agents concentrations. The research results will be useful and important in obtaining sorbents for extracting chromium (VI) ions from aqueous media. [ABSTRACT FROM AUTHOR]

The process of decontamination of liquid radioactive wastes, containing Cs-137 and Sr-90, by the sorption method using clay sorbents, modified by copper and copper-potassium ferrocyanides, and also antimony hydroxide was studied in the paper. The adsorption capacity of samples of the modified clay in the presence of equipment corrosion products, ions of cobalt and manganese, was studied. It was found that the modified clay sorbents are effective in the process of decontamination of liquid radioactive wastes since Cs-137 is removed by 99-100 % and Sr-90 - by 70-97 %. Ions of cobalt and manganese do not inhibit the adsorption of Cs-137 while the adsorption of strontium is reduced by 5-10 %. Based on the analysis of results of adsorption of Cs-137 in the presence of cobalt, the hypothesis on a significant adsorption capacity of modified clay samples on cobalt was stated. [ABSTRACT FROM AUTHOR]