ABSTRACT Fe3O4 nanopowders prepared by three different procedures (vapor-phase synthesis, chemica... more ABSTRACT Fe3O4 nanopowders prepared by three different procedures (vapor-phase synthesis, chemical precipitation from aqueous solutions, and laser evaporation) have been characterized by X-ray photoelectron spectroscopy before and after chromium(VI) sorption from aqueous solutions. The results demonstrate that, during sorption, the chromium is concentrated in the magnetite at a level of several atomic percent, and its oxidation state is 3+. The mechanism of chromium sorption on magnetite particles is discussed.
ABSTRACT Magnetite (Fe3O4) nanopowders have been characterized by voltammetry before and after he... more ABSTRACT Magnetite (Fe3O4) nanopowders have been characterized by voltammetry before and after hexavalent chromium sorption from aqueous solutions. The results demonstrate that the interaction of Cr(VI) in solution with a magnetite precipitate leads to a redox reaction on the magnetite surface: oxidation of Fe(II) to Fe(III) and reduction of Cr(VI) to Cr(III).
Comparative tests were conducted on the inhibition of scale formation from natural salt waters wi... more Comparative tests were conducted on the inhibition of scale formation from natural salt waters with the help of the l-IA+-13A, WOMC and BEL-GARDEV. Chemical composition of the scale formed was examined. The investigations were conducted on a laboratory installation. The simuIated solutions of the Black and Caspian Sea waters as well as deep-well water were used as natural waters. The investigations demonstrated that the growth of reagent concentrations in solution results in decrease of calcium ion contents and magnesium ions increase in scale. The data obtained indirectly point to the formation of undissolved compounds with magnesium ions in the reagents tested and the impact of Mg-ions on efficiency of the latter for inhibiting the calcium carbonate scaling.
ABSTRACT Comparative tests of a number of chemical additives-scale formation inhibitors, of phosp... more ABSTRACT Comparative tests of a number of chemical additives-scale formation inhibitors, of phosphonate (ΠAΦ-13A ), polyelectrolyte (AMEROYAL) type and others, being applied in the USSR and abro-ad were carried out. The investigations were conducted on a laboratory installation. The processes of scale formation in the form of magnesium hydroxide, calcium carbonate and sulphate were simulated in them. In order to eliminate mutual superposition of scale formation in them. In order to eliminate mutual superposition of scale formation processes of different types that is inevitable at sea water use, simulated solutions were applied. It permitted to evaluate the effect of chemical additives on the formation process of each scale type. From the chemical additives tested there were determined the most efficient inhibitors of scale formation of magnesium hydroxide, calcium silphate and carbonate. It was shown that most of the chemical additives didn't inhibit magnesium hydroxide scale formation.
ABSTRACT A process of hydrochloric acid transfer through an anion exchange membrane at its regene... more ABSTRACT A process of hydrochloric acid transfer through an anion exchange membrane at its regeneration from acid wastewaters has been studied. An equation describing the diffusion process of components in the examined membrane system has been derived and experimentally tested. General mass transfer coefficients of hydrochloric acid and molecules of NaCl, CdCl2, NiCl2, and ZnCl2 through the anion exchange membrane have been determined.
Protection of Metals and Physical Chemistry of Surfaces, 2021
The physicochemical and sorption properties of MIU-S carbon sorbent have been studied. The studie... more The physicochemical and sorption properties of MIU-S carbon sorbent have been studied. The studies were carried out on a model solution of nickel(II) sulfate containing an additional 400 mg/L sodium sulfate in the pH range of 5-8. It has been shown that the MIU-S sorbent is capable of removing nickel(II) ions from solution by the mechanism of simple monomolecular adsorption described by the Langmuir equation. The parameters of this equation are determined for different pH values of the model solution. It was found that, with an increase in the pH of the solution from 5 to 8, the efficiency of sorption of nickel(II) ions by the MIU-S sorbent increases. The sorption properties of MIU-S with respect to nickel(II) ions are compared with the properties of other carbon (coal) sorbents described in the literature.
Protection of Metals and Physical Chemistry of Surfaces, 2021
The present review is devoted to the sorption properties of magnetite towards hexavalent chromium... more The present review is devoted to the sorption properties of magnetite towards hexavalent chromium ions and the possibility of its use as a sorbent for removing these toxic ions from contaminated aqueous solutions. The behavior of magnetite nanoparticles in aqueous solutions has been also investigated. It has been shown that two processes occur simultaneously during the sorption of chromium(VI) ions by magnetite: ordinary adsorption and chemisorption (redox reaction between hexavalent chromium ions and magnetite). The latter is accompanied by the oxidation of iron(II) in magnetite to iron(III) and the reduction of chromium(VI) ions to chromium(III) with the formation of maghemite and a number of other compounds, including mixed chromium(III) compounds with iron, in the surface layer of magnetite (or onto its surface). It has been demonstrated that the kinetics of the redox process between chromium(VI) and magnetite is described by the first-order reaction equation with respect to the concentration of chromium(VI) ions in a solution. As a result of chemisorption, unlike the case of traditional sorbents, chromium(VI) is irreversibly bound by magnetite, which eliminates the reentry of its ions into the environment. Here, the sorption capacity of magnetite irreversibly decreases in the course of its saturation with chromium. In addition, the sorption capacity of magnetite towards chromium(VI) ions also decreases along with increasing pH of the purified solution, and at pH > 11 it becomes almost zero.
The sorption of copper(II) ions by the mineral filter material MS was studied. The study was carr... more The sorption of copper(II) ions by the mineral filter material MS was studied. The study was carried out on a model solution of copper(II) sulfate containing an additional 400 mg/dm3 of sodium sulfate. It demonstrates that the sorption properties of MS are due to the simultaneous action of two factors. The first is associated with an increase in the pH of the solution being purified when the MS material is introduced into it, which leads to the precipitation of copper(II) ions from the solution in the form of the corresponding hydroxide. The second is the ability of the MS to remove copper(II) ions from the solution by the mechanism of adsorption described by the Langmuir equation. It was found that with an increase in the pH of the solution from 4 to 6.7, the adsorption of copper(II) ions on the surface of the MS increases (ranges of pH<4 and pH>6.7 have not been studied). The found values of the MS monolayer capacity with respect to copper(II) ions turned out to be comparabl...
Experimental data are considered concerning growth of calcium sulfate (gypsum) crystals from elec... more Experimental data are considered concerning growth of calcium sulfate (gypsum) crystals from electrolyte solutions on a heated metal surface. The specific surface energy and the activation energy of the growth of calcium sulfate crystals are determined
The attempt to consider the influence of particles solvation of of dissolved substance on the nuc... more The attempt to consider the influence of particles solvation of of dissolved substance on the nucleation and growth of crystals during crystallization from solutions in classical thermodynamic theory of nucleation has been undertaken. A number of interesting relations between activation energies of nucleation and of growth of crystals are obtained. Comparison to the published literary data is carried out.
The kinetics of crystallization of a number of salts from aqueous solutions of ethanol was studie... more The kinetics of crystallization of a number of salts from aqueous solutions of ethanol was studiedunder isothermal conditions on a setup enabling simultaneous automated recording of the electrical conduc-tivity, optical transmission, light scattering (at an angle of 90° to the incident light beam) of a super-saturated solution in salt crystallization. The rate coefficients of crystal growth were determined.
Sedimentation of nanopowders of magnetite Fe3O4 in water solution was studied by optical method. ... more Sedimentation of nanopowders of magnetite Fe3O4 in water solution was studied by optical method. Larger particles (50 nm) are sedimenting effectively during several minute, while for particles close to 20 nm more than 24 hours is required for full sedimentation in a solution of 5 g/l. Although the magnetization of nanopowders is noticeably less than that in a bulk material it provides a significant contribution to attractive interactions between particles, thus promoting the heavy aggregates formation. It has been shown that sedimentation rate can be strongly increased under the action of a gradient magnetic field dH/dz = 1.7 kOe/cm.
The problem of choosing the most effective concentration of seed crystals for controlling the sup... more The problem of choosing the most effective concentration of seed crystals for controlling the supersaturation and scale growth rate in flow-through crystallizers and evaporating apparatus is considered theoretically. Equations describing these processes are derived and compared with published experimental data.
Current research interests: solid-state physics and chemistry, crystallization and mass-exchange ... more Current research interests: solid-state physics and chemistry, crystallization and mass-exchange processes, adsorption and colloid phenomena in solutions, inorganic synthesis.
ABSTRACT Fe3O4 nanopowders prepared by three different procedures (vapor-phase synthesis, chemica... more ABSTRACT Fe3O4 nanopowders prepared by three different procedures (vapor-phase synthesis, chemical precipitation from aqueous solutions, and laser evaporation) have been characterized by X-ray photoelectron spectroscopy before and after chromium(VI) sorption from aqueous solutions. The results demonstrate that, during sorption, the chromium is concentrated in the magnetite at a level of several atomic percent, and its oxidation state is 3+. The mechanism of chromium sorption on magnetite particles is discussed.
ABSTRACT Magnetite (Fe3O4) nanopowders have been characterized by voltammetry before and after he... more ABSTRACT Magnetite (Fe3O4) nanopowders have been characterized by voltammetry before and after hexavalent chromium sorption from aqueous solutions. The results demonstrate that the interaction of Cr(VI) in solution with a magnetite precipitate leads to a redox reaction on the magnetite surface: oxidation of Fe(II) to Fe(III) and reduction of Cr(VI) to Cr(III).
Comparative tests were conducted on the inhibition of scale formation from natural salt waters wi... more Comparative tests were conducted on the inhibition of scale formation from natural salt waters with the help of the l-IA+-13A, WOMC and BEL-GARDEV. Chemical composition of the scale formed was examined. The investigations were conducted on a laboratory installation. The simuIated solutions of the Black and Caspian Sea waters as well as deep-well water were used as natural waters. The investigations demonstrated that the growth of reagent concentrations in solution results in decrease of calcium ion contents and magnesium ions increase in scale. The data obtained indirectly point to the formation of undissolved compounds with magnesium ions in the reagents tested and the impact of Mg-ions on efficiency of the latter for inhibiting the calcium carbonate scaling.
ABSTRACT Comparative tests of a number of chemical additives-scale formation inhibitors, of phosp... more ABSTRACT Comparative tests of a number of chemical additives-scale formation inhibitors, of phosphonate (ΠAΦ-13A ), polyelectrolyte (AMEROYAL) type and others, being applied in the USSR and abro-ad were carried out. The investigations were conducted on a laboratory installation. The processes of scale formation in the form of magnesium hydroxide, calcium carbonate and sulphate were simulated in them. In order to eliminate mutual superposition of scale formation in them. In order to eliminate mutual superposition of scale formation processes of different types that is inevitable at sea water use, simulated solutions were applied. It permitted to evaluate the effect of chemical additives on the formation process of each scale type. From the chemical additives tested there were determined the most efficient inhibitors of scale formation of magnesium hydroxide, calcium silphate and carbonate. It was shown that most of the chemical additives didn&#39;t inhibit magnesium hydroxide scale formation.
ABSTRACT A process of hydrochloric acid transfer through an anion exchange membrane at its regene... more ABSTRACT A process of hydrochloric acid transfer through an anion exchange membrane at its regeneration from acid wastewaters has been studied. An equation describing the diffusion process of components in the examined membrane system has been derived and experimentally tested. General mass transfer coefficients of hydrochloric acid and molecules of NaCl, CdCl2, NiCl2, and ZnCl2 through the anion exchange membrane have been determined.
Protection of Metals and Physical Chemistry of Surfaces, 2021
The physicochemical and sorption properties of MIU-S carbon sorbent have been studied. The studie... more The physicochemical and sorption properties of MIU-S carbon sorbent have been studied. The studies were carried out on a model solution of nickel(II) sulfate containing an additional 400 mg/L sodium sulfate in the pH range of 5-8. It has been shown that the MIU-S sorbent is capable of removing nickel(II) ions from solution by the mechanism of simple monomolecular adsorption described by the Langmuir equation. The parameters of this equation are determined for different pH values of the model solution. It was found that, with an increase in the pH of the solution from 5 to 8, the efficiency of sorption of nickel(II) ions by the MIU-S sorbent increases. The sorption properties of MIU-S with respect to nickel(II) ions are compared with the properties of other carbon (coal) sorbents described in the literature.
Protection of Metals and Physical Chemistry of Surfaces, 2021
The present review is devoted to the sorption properties of magnetite towards hexavalent chromium... more The present review is devoted to the sorption properties of magnetite towards hexavalent chromium ions and the possibility of its use as a sorbent for removing these toxic ions from contaminated aqueous solutions. The behavior of magnetite nanoparticles in aqueous solutions has been also investigated. It has been shown that two processes occur simultaneously during the sorption of chromium(VI) ions by magnetite: ordinary adsorption and chemisorption (redox reaction between hexavalent chromium ions and magnetite). The latter is accompanied by the oxidation of iron(II) in magnetite to iron(III) and the reduction of chromium(VI) ions to chromium(III) with the formation of maghemite and a number of other compounds, including mixed chromium(III) compounds with iron, in the surface layer of magnetite (or onto its surface). It has been demonstrated that the kinetics of the redox process between chromium(VI) and magnetite is described by the first-order reaction equation with respect to the concentration of chromium(VI) ions in a solution. As a result of chemisorption, unlike the case of traditional sorbents, chromium(VI) is irreversibly bound by magnetite, which eliminates the reentry of its ions into the environment. Here, the sorption capacity of magnetite irreversibly decreases in the course of its saturation with chromium. In addition, the sorption capacity of magnetite towards chromium(VI) ions also decreases along with increasing pH of the purified solution, and at pH > 11 it becomes almost zero.
The sorption of copper(II) ions by the mineral filter material MS was studied. The study was carr... more The sorption of copper(II) ions by the mineral filter material MS was studied. The study was carried out on a model solution of copper(II) sulfate containing an additional 400 mg/dm3 of sodium sulfate. It demonstrates that the sorption properties of MS are due to the simultaneous action of two factors. The first is associated with an increase in the pH of the solution being purified when the MS material is introduced into it, which leads to the precipitation of copper(II) ions from the solution in the form of the corresponding hydroxide. The second is the ability of the MS to remove copper(II) ions from the solution by the mechanism of adsorption described by the Langmuir equation. It was found that with an increase in the pH of the solution from 4 to 6.7, the adsorption of copper(II) ions on the surface of the MS increases (ranges of pH<4 and pH>6.7 have not been studied). The found values of the MS monolayer capacity with respect to copper(II) ions turned out to be comparabl...
Experimental data are considered concerning growth of calcium sulfate (gypsum) crystals from elec... more Experimental data are considered concerning growth of calcium sulfate (gypsum) crystals from electrolyte solutions on a heated metal surface. The specific surface energy and the activation energy of the growth of calcium sulfate crystals are determined
The attempt to consider the influence of particles solvation of of dissolved substance on the nuc... more The attempt to consider the influence of particles solvation of of dissolved substance on the nucleation and growth of crystals during crystallization from solutions in classical thermodynamic theory of nucleation has been undertaken. A number of interesting relations between activation energies of nucleation and of growth of crystals are obtained. Comparison to the published literary data is carried out.
The kinetics of crystallization of a number of salts from aqueous solutions of ethanol was studie... more The kinetics of crystallization of a number of salts from aqueous solutions of ethanol was studiedunder isothermal conditions on a setup enabling simultaneous automated recording of the electrical conduc-tivity, optical transmission, light scattering (at an angle of 90° to the incident light beam) of a super-saturated solution in salt crystallization. The rate coefficients of crystal growth were determined.
Sedimentation of nanopowders of magnetite Fe3O4 in water solution was studied by optical method. ... more Sedimentation of nanopowders of magnetite Fe3O4 in water solution was studied by optical method. Larger particles (50 nm) are sedimenting effectively during several minute, while for particles close to 20 nm more than 24 hours is required for full sedimentation in a solution of 5 g/l. Although the magnetization of nanopowders is noticeably less than that in a bulk material it provides a significant contribution to attractive interactions between particles, thus promoting the heavy aggregates formation. It has been shown that sedimentation rate can be strongly increased under the action of a gradient magnetic field dH/dz = 1.7 kOe/cm.
The problem of choosing the most effective concentration of seed crystals for controlling the sup... more The problem of choosing the most effective concentration of seed crystals for controlling the supersaturation and scale growth rate in flow-through crystallizers and evaporating apparatus is considered theoretically. Equations describing these processes are derived and compared with published experimental data.
Current research interests: solid-state physics and chemistry, crystallization and mass-exchange ... more Current research interests: solid-state physics and chemistry, crystallization and mass-exchange processes, adsorption and colloid phenomena in solutions, inorganic synthesis.
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Papers by Oleg Linnikov