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2014, №1

сс. 4-11

Articles

Morphology of acrylonitrile copolymers with methylacrylate and itaconic acid, as well as with its derivatives, obtained in supercritical carbon dioxide media

A.V. Shlyakhtin, I.E. Nifant'ev, D.A. Lemenovskii, D.P. Krut'ko, V.V. Bagrov, P.S. Timashev, V.K. Popov, V.N. Bagratashvili.

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Key words: carbon dioxide, polyacrylonitrile, itaconic acid, polymerization, particles

Ternary copolymers of acrylonitrile with methylacrylate and itaconic acids and with
derivatives of the latter — monomethyl ester (MME), monoethyl ester (MEE),
monoamide, mono-n-octylamide, are synthesized in supercritical carbon dioxide
medium. The morphology of the obtained copolymers is investigated using scanning
electron microscopy. Copolymers with itaconic acid, its MME and MEE form regular
particles of about 1 μm size with no addition of any stabilizer.

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2014, №1

сс. 12-28

Articles

Key words: liptobiolith coal, supercritical water, liquefaction, desulfurization, kinetics and mechanisms of reactions

Liquefaction of liptobiolith coal in steam and supercritical water (SCW) flow at
constant increase of temperature from 300 up to 470 °C is studied. Temperature
dependencies of the yield of liquid and volatile products and apparent kinetic parameters
of the process are obtained. The yields of oil, resin, asphaltene and volatile products are
estimated as 23.2, 16.1, 5.1 and 14.1% of the coal organic matter (COM), respectively.
Participation of water molecules in thermochemical transformations of COM resulted
in the 13.2% wt. increase of oxygen amount in the conversion products and residue.

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2014, №1

сс. 29-39

Articles

Structure and properties of ultrahigh molecular weight polyethylene containing silver nanoparticles

P.S. Timashev, N.V. Minaev, D.V. Terehin, E.V. Kuznetsov, V.V. Malinovskaya, V.V. Parfenov, V.N. Bagratashvili, O.P. Parenago.

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Key words: supercritical carbon dioxide, ultrahigh molecular weight polyethylene, organometallic precursor, modification, nanoindentation, tribology characteristics, friction coefficient

Microstructure and mechanical properties of ultrahigh molecular weight polyethylene
(UHMWPE) containing metallic silver nanoparticles introduced via impregnation
with Ag-containing precursor in supercritical carbon dioxide are studied. The
nanoindentation experiments showed that the elastic modulus of silver-containing
composites increases by 40—50% compared to the initial UHMWPE samples, while
the hardness of modified samples remains largely unchanged. Measured values of friction
coefficients for the initial and modified polymers are comparable at loads ranging
from 50 to 400 N.

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2014, №1

сс. 40-47

Articles

Oxidative treatment of waste water formed during cellulose production from rape straw in supercritical conditions

E.Sh. Gayazova, R.A. Usmanov, I.G. Shayhiev, F.M. Gumerov, R.Z. Musin, S.V. Fridland.

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Key words: oxidation in supercritical water, waste water treatment, cellulose production, coagulation, flocculation

The method of oxidative waste water (WW) treatment in the supercritical conditions
(SC) is considered. It is demonstrated that the values of water parameters required
for the downstream biological purification are accessible if coagulation-flocculation
treatment of WW on the first stage is combined with oxidation in the SC on the
second stage. The necessity of such combination is caused by low degree of lignin
degradation in the conditions of oxidative treatment (400 °C, 24 MPa,
Н2О2 as oxidant).

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2014, №1

сс. 48-54

Articles

Key words: photochromism, spirocompounds, SCF impregnation, luminescence, electron-donor compounds

Aromatic electron-donor compounds (EDC) (such as toluene and dibutyl phthalate)
are found to affect the content of photochromic spiroantrooxazine (SAO) and to
control the ratio of its colored forms (B and Bx) introduced into thermoplastic
polymeric matrixes (e.g. polyvinylchloride and F-42 fluoroplast) using the supercritical
fluid impregnation (SCFI). The presence of EDC in impregnated polymers induces
the reciprocal transformations of the SAO colored form B and Bx and
increases the rate their «dark» bleaching.

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2014, №1

сс. 55-61

Articles

Key words: supercritical fluid extraction, liquid and/or supercritical carbon dioxide, spent nuclear fuel reprocessing, uranium, fission products, complexation, tributyl phosphate, aqueous ferric nitrate solution

The behavior of uranium and simulators of fission products during the reprocessing
of a model spent nuclear fuel in subacidic ferric nitrate solution using supercritical
carbon dioxide containing tributyl phosphate (TBP) is studied. A quantitative isolation
of uranium from the ferric nitrate solution simultaneously with its separation from
the present fission products can be reached in these conditions. Isolation of uranium
from the TBP phase was performed by its back extraction by water hydrogen peroxide
solution simultaneously with preci pitation in the form of uranium peroxide. A high
efficiency of uranium purification from all fission products is achieved, which allows
one to reuse uranium in a nuclear fuel cycle.

doi:

2014, №1

сс. 62-79

Articles

Key words: asphaltite, supercritical water, aluminum, hydrogenation, desulfurization

The conversion of asphaltite (gross-formula
CH1.23N0.017S0.037O0.01) in supercritical water
(SCW) flow at 400 °C and 30 MPa with and without addition of aluminum shavings is
investigated. Composition and amount of products and insoluble conversion residue
are determined by means of liquid-adsorption chromatography, elemental analysis, IR
and NMR 1H spectroscopy, mass spectrometry and gas chromatography/mass spectrometry.
It is found out that SCW not only dissolves asphaltite components, but it
participates in redox reactions. Hydrogen and heat evolution during the aluminum
oxidation by SCW provide for in situ hydrogenation of asphaltite, increase the fraction
of aromatic and polyaromatic compounds in liquid products and decrease the yield of
insoluble conversion residue from 44.5 to 11.3 %. If aluminum is added, the degree of
asphaltite desulfurization, as a result of sulfur removal in the form of H2S, increases by
more than 3.5 times.

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2014, №1

сс. 80-85

Articles

Key words: inactivation, Escherichia coli, CO2, tetrafluoroethane, ethanol

The kinetics of E. coli bacteria inactivation is studied in compressed carbon dioxide
and tetrafluoroethane with and without ethanol addition. The possibility of decreasing
the number of survived cells by 7 orders of magnitude when up to 5% vol. of ethanol
is added to the main fluid is demonstrated.

doi:

2014, №1

сс. 86-94

Articles

Cleaning of cantilevers for atomic force microscopy in supercritical carbon dioxide

P.S. Timashev, S.L. Kotova, N.N. Glagolev, N.A. Aksenova, A.B. Solovieva, V.N. Bagratashvili.

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Key words: atomic force microscopy, cantilevers, surface cleaning, supercritical carbon dioxide

A new method for gentle cleaning of cantilevers used in the atomic force microscopy
(AFM) in supercritical carbon dioxide (SC-CO2) is suggested. Artificial organic
pollutant (polyethylmetacrilate) can be removed by treatment in SC-CO2 without any
damage of the sample structure and operational characteristics. Using Raman
spectroscopy and scanning electron microscopy a complete removal of the pollutant
from the sample surface is proven. After treatment in SC-CO2 no bands attributed to
the organic pollutant are present in Raman spectra. The images of calibration grids
obtained using the SC-CO2 treated cantilevers are more sharp and clear compared to
those obtained using the same cantilevers in «as obtained» state without any treatment;
the number of artifact features on the images obtained using the SC-CO2 treated
cantilevers is also lower.

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2014, №2

сс. 4-10

Articles

Key words: supercritical carbon dioxide, photosensitized oxidation, anthracene, porphyrins

A photosensitized oxidation of anthracene and cholesterol in supercritical carbon
dioxide (SC-CO2) in the presence of fluorinated tetraphenylporphyrins (FTPP)
containing hydrocarbon substituents with different chain lengths (characterized by
the number of carbon atoms n) in para-position of the phenyl rings as sensitizers is
carried out for the first time. The rate of such process in SC-CO2 is much higher
than in conventional organic solvents, in chloroform in particular. The value of the
apparent rate constant of anthracene photooxidation keff increases with increasing n
due to a higher probability of the formation of the complex between the substrate and
a more spatially extended FTPP molecule at increasing n number. Such complex can be
an intermediate in the formation of anthraquinone — the only product in the
photooxidation of anthracene in SC-CO2.

doi:

2014, №2

сс. 11-26

Articles

Key words: supercritical extraction, garlic, carbon dioxide, thiosulfinates, high performance liquid chromatography (HPLC)

For the first time a detailed investigation of destruction of thiosulfinates from garlic
supercritical extract in solvents of different polarity (water, ethyl alcohol, acetonitrile,
dimethylsulfoxide, methylene chloride and hexane) is performed. Qualitative and
quantitative analysis of thiosulfinate destruction products is carried out. A new HPLC
analytical procedure is developed that offers a possibility to determine both initial
thiosulfinates, as well as their sulfur-containing destruction products. As a result, a way
of directing the thiosulfinates destruction process to the formation of desired substances
(ajoenes, dithiines, trisulfides, etc.) is suggested. The obtained results may be used for
studying medico-biological applications of garlic products, and also for their
manufacturing, storage and analysis.

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2014, №2

сс. 27-39

Articles

Key words: fibrillar porous media, subcritical liquid, supercritical fluid, bulk modulus, relaxation of deformations, speckle correlometry

Isothermal relaxation of deformations in the fibrillar porous layers saturated by
subcritical or supercritical carbon dioxide is studied using full-field speckle correlometry
at various temperatures. The relaxation of deformations is caused by the transition of
the «porous layer — fluid» system from one equilibrium state to another as a result of
partial drop of pressure. It is found that the relaxation time reaches its maximal value
in the vicinity of the critical point and rapidly falls down with the increasing deviation
of the system temperature from the critical temperature of carbon dioxide. Possible
mechanisms of hydrodynamic relaxation of the fluid density inside the layer and
viscoelastic relaxation of the porous matrix are discussed. It is shown that the
experimentally observed slow relaxation of the system is governed by the viscoelastic
relaxation of the porous matrix in the condition of equal values of the fluid density
inside the layer and outside it.

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2014, №2

сс. 40-50

Articles

Frenkel line and supercritical technologies

V.V. Brazhkin, A.G. Lyapin, V.N. Ryzhov, K. Trachenko, Yu.D. Fomin, E.N. Tsiok.

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Key words: microscopic dynamics of liquids and gases, superhigh pressures, fluids viscosity, supercritical technologies

Up to date supercritical technologies use the fluids like CO2, H2O etc. at temperatures
and pressures close to the corresponding critical points. It is not clear up to date if
the near-critical fluctuations are important for the solubility processes and chemical
reactions in the fluids. Meanwhile recently we have shown that at the temperatures and
pressures much higher than the critical ones there are qualitative changes of almost
all fluid properties. The paper briefly summarizes the last results of the search and
study of P,T-parameters of the changes of dynamics in supercritical fluids. We found
that actually these parameters correspond to the narrow band — «Frenkel line». The
crossing this line during temperature increase corresponds to the disappearance of
the shear rigidity of a fluid at all available frequencies. Thus Frenkel line can be considered
as a boundary between a liquid and a dense gas at superhigh pressures far from the
critical point. Very recently we have proposed very simple and rigorous criterion to
find Frenkel line position based on the analysis of autocorrelation function of particle
velocities. We plan to use the data of the Frenkel line parameters for real fluids to push
supercritical technologies to the superhigh pressure region far from the critical point.

doi:

2014, №2

сс. 51-63

Articles

Physico-chemical properties of betulin and CO2-extract from the birch tree bark

V.F. Uryash, N.Yu. Kokurina, V.N. Larina, E.A. Kashtanov, A.E. Gruzdeva.

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Key words: birch tree barks, CO2-extract, biologically active substances, betulin, thermodynamic characteristics, physico-chemical properties

Supercritical fluid extraction with carbon dioxide is used to extract biologically active
substances from the bark of the birch tree (Betula pendula). Phase and relaxation
transitions (melting, crystallization, evaporation, vitrification) in these samples are
studied using differential thermal analysis between 80 and 550 K. Betulin was isolated
and purified from CO2-extracts of birch bark. Its heat capacity in the temperature
range of 80—350 K, as well as temperatures of phase and relaxation transitions and
thermochemical characteristics (standard enthalpy of combustion and formation)
are measured.

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2014, №2

сс. 64-73

Articles

Supercritical fluid encapsulation of acizol into aliphatic polyether microparticles

S.E. Bogorodski, L.I. Krotova, S.V. Kursakov, S.A. Minaeva, V.K. Popov, V.I. Sevastyanov.

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Key words: antidote against carbon monoxide, acizol, supercritical carbon dioxide, controllable drug release

Encapsulation of pharmaceutical grade acizol into bioresorbable D,L-polylactide and
polylactoglycolide microparticles using supercritical carbon dioxide is studied. An
effective way for fabrication of polymer fine powders (mean particle size ca. 10—20
μm) containing up to 20 % wt. of bioactive component without any organic solvent is
suggested. Raman spectroscopy with spatial resolution is employed to analyze the
distribution of acizol throughout the volume of individual polymer microparticles
and kinetics of its release into the saline solution. A steep release (ca. 40—80% of the
total amount of encapsulated substance) from the samples under study during the
first hour followed by gradual, almost linear release between fourth and fourteenth
days of experiment with cumulative outcome of up to 100% is observed.

doi:

2014, №2

сс. 74-82

Articles

Key words: critical fluid, gravity field, fluctuation structure

The mechanism of the physical processes underlying the wide practical use of the
unique properties of the substance in critical condition — critical fluid (CF) in the
up-to-date technologies. In view of the fluctuation theory of phase transitions (FTPT)
these mechanisms are certainly related to fluctuation structure of critical fluid defining
its equilibrium and kinetic properties. Such structural characteristics of critical fluid
are: the value of the correlation radius Rc system, the number of fluctuations of the
order parameter
NфRc-3
in one mole of critical fluid, the size of the fluctuation part of the thermodynamic potential
FФ*=NфkTк/(PкVк)=C0Rc-3.
In the work of these
structural characteristics of critical fluid have been investigated by experimental data
of the gravitational effect: high-altitude and temperature dependences of dependences
of scattered light intensity I(z, t) in heterogeneous substance n-pentane near the
critical temperature of evaporation. Using these results and literature data on the processes
of formation Al2O3 nanoparticles using CF-H2O, speeds of distribution of molecules of
substance are estimated – vf ≈ 106 cm/s in the formation and decay of fluctuations of
the order parameter. It has been concluded, that such high speed of molecules of a
substance due to the unique properties of the critical fluid in their practical use in a
number of technological processes.

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2014, №2

сс. 83-92

Articles

Key words: masters training, educational program, competence approach, supercritical fluid technologies, processing of hydrocarbon feedstocks

In 2013, at the Department of Heat Engineering of the Kazan National Research
Technological University a master course program «Supercritical fluid technologies
for the hydrocarbon feedstock deep refining processes» with international partici pation
was developed. This educational program that involves the universities of Astana (Kazakh
National Al-Farabi University) and Paris (Galileo University Paris-XIII) is scheduled
for implementation in academic year 2014/2015. The «Supercritical fluid technologies
for the hydrocarbon feedstock deep refining processes» is relevant and innovative
for the Russian Federation in general. It is of particular interest for the Republic of
Tatarstan, where 127 oil fields uniting more than 3000 deposits are discovered, and the
production and processing of hydrocarbon resources is a priority task. The program is
based on the competence approach. It includes a list of target competences, a plan of
their development and a standard content of student research work.

2014, №2

сс. 93-96

Information

2014, №3

сс. 4-12

Articles

Xenogenic bone matrix processed with supercritical carbon dioxide as potential osteoplastic material

D.Yu. Zalepugin, V.V. Zaitsev, N.A. Tilkunova, I.V. Chernyshova, I.I. Selezneva, Yu.A. Nikonova, M.I. Vlasov.

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Key words: supercritical extraction, porosity, carbon dioxide, xenogenic matrix, osteoplastic materials

Multistage environmentally benign method of xenogenic bone matrix processing in
sub- and supercritical media is developed. This method provides with a fast matrix
deli pidation in supercritical carbon dioxide, deproteinization by treatment with 3%
hydrogen peroxide solution followed by washing in subcritical water for removal of
polar substances. The final treatment with supercritical carbon dioxide serves to remove
residual non-polar components. A method to control the porosity of xenogenic bone
matrix on several stages of purification is suggested. Preliminary data indicate that cell
test system based on the allogenic osteoid cell line Th-1 can be used for evaluation of
primary adhesion and cell proliferation on the surface of purified bone matrix.

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2014, №3

сс. 13-20

Articles

Key words: isochoric heat capacity, adiabatic calorimeter, phase transition, «water—n-hexane» system

The isochoric heat capacity of «n-hexane — water» system is studied using the adiabatic
calorimeter in the range of water mole fraction between 0.256 and 0.935 at 300—600 K
in a wide range of densities. The obtained experimental critical curves of liquid—
vapor phase equilibrium are described by an equation that corresponds to the theory
of critical phenomena.

doi: