V. I. Platonov

Dust structures in cryogenic gas discharges

Results are given of experimental investigations of dust structures of monodisperse particles in a low-pressure dc glow discharge at temperatures of liquid nitrogen ( T = 77 K ) and liquid helium ( T = 4.2 K ) . It is found that the cooling of discharge at invariant discharge current and neutral gas density causes a decrease in the interparticle spacing in structures and an increase in the kinetic energy of dust particles. The forming of a superdense dust structure with free boundaries is observed for the first time at 4.2 K .

Removal of Cr(VI) from aqueous solutions by magnetite nanoparticles with different sizes and crystal structure

AbstractIn this work a few nanopowders of magnetite (Fe3O4) produced by different methods were used as a sorbents. Three techniques were applied to make the nanopowders: (1) gas-phase synthesis, (2) chemical precipitation from water solution, and (3) laser atomization. Using these methods, the particles with different sizes and crystal structure have been produced. The effects of the particles size and structure of nanopowders on the removal of toxic Cr(VI) from an aqueous solution imitating ground waters and wastewaters with pHu2009=u20097.4–7.8 were studied at different solution temperatures. It is shown that magnetite is effective sorbent for the removal of Cr(VI) from polluted natural waters and sewage. It is found that sorption of Cr(VI) by magnetite is irreversible and has chemisorption character, and even small rise in temperature of the solution during the sorption process sharply increases efficiency of the sorption.

Thermodynamics of the adsorption of volatile organic compounds in a binary polydimethylsiloxane-permethylated β-cyclodextrin stationary phase, as measured by gas chromatography

The sorption behavior of 29 organic compounds in a binary polydimethylsiloxane-permethylated β-cyclodextrin stationary phase is investigated using gas chromatography. The effect of the sorbates’ polarity, shape, and chirality on the formation of sorbate-cyclodextrin inclusion complexes is studied.

Planar gas chromatography column on glass plate with nanodispersed silica as the stationary phase

The paper presents the GC column in the plane of the glass plate with the adsorption layer nanodispersed silica. Created gas chromatographic column allows to separate a mixture of five alkanes from pentane to nonane in isothermal (90 ° C) mode less than one minute.

Planar gas chromatography column on aluminum plate with multi-walled carbon nanotubes as stationary phase

The high selectivity of the adsorption layer for low-boiling alkanes is shown, the separation factor (α) couple iso-butane / butane is 1.9 at a column temperature of 50 °C.The paper presents sorption and selective properties of planar gas chromatography column on aluminum plate with multi-walled carbon nanotubes as the stationary phase.

Planar microchromatographic columns for gas chromatography

The adsorption and selective properties of aluminum-based planar microcolumns filled with the Carbopack B adsorbent are studied. The effect of geometrical parameters of the columns on their chromatographic properties is considered on an example of the separation of a mixture of light hydrocarbons. The advantages of planar microcolumns compared to conventional packed chromatographic columns are revealed.

A gas chromatograph based on planar systems

A chromatographic system consisting of a microinjector with the volume of sampling loop 10 µL, a microchromatographic column with nanodisperse silica particles on a planar aluminum plate, and a catalytic combustion detector adapted for work on planar surface has been presented. A possibility of using the developed microchromatograph for the analysis of a mixture of low-boiling alkanes with preserving performance characteristics of stationary gas chromatographs has been shown. The proposed chromatographic system ensured a substantial decrease in the time of analysis and the significant reduction of the dimensions of the system, energy consumption, and cost of the manufacture and service of the chromatographic equipment.

Application Of Fe3O4 Nanoparticles For Metallic Cations Removal From Water Solution

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/dzu2009=u20091.7u2009kOe/cm.