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2014, №4

pp. 3-11

Articles

Key words: supercritical carbon dioxide, bioresorbable polymers, SCF-micronization, SAS, hydroxypropylmethylcellulose

Micronization of hydroxypropylmethylcellulose using supercritical antisolvent (SAS) method is studied. The influence of various parameters, such as solvent type, polymer concentration, pressure, solution to supercritical CO2 flow rate ratio on morphology of particles is discussed. The possibility of obtaining spherical or elli ptical shape hydroxypropylmethylcellulose particles of submicron size (190-620 nm) that depends on the process parameters is demonstrated.

2014, №4

pp. 12-21

Articles

Key words: extraction, subcritical water, eucalyptus viminalis, 1,8-cineole

Extraction of biologically active substances from the leaves of eucalyptus viminalis is carried out by subcritical water in the temperature range 120—200 °C and a pressure of 5 MPa, as well as solutions of ethanol in water of different concentrations at 200 °C and 5 MPa. The extracts are analyzed using gas chromatography-mass spectrometry. Identification of the detected volatile organic compounds is realized. The content of α-pinene, β-pinene, α-phellandrene, p-cymene, 1,8-cineole in obtained extracts is determined.

2014, №4

pp. 22-31

Articles

Forming of long-living «colored» spiroantrooxazine isomers incorporated into fluoroplast F-42 matrix in supercritical carbon dioxide medium

A.V. Cherkasova, N.N. Glagolev, A.S. Kopylov, T.S. Zarkhina, P.S. Timashev, V.N. Bagratashvili, A.B. Solovieva.

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Key words: supercritical fluid impregnation, supercritical carbon dioxide, thermoplastic polymers, photochrome indoline spirocompounds, toluene, spectrophotometry

It is demonstrated that the generation of isomer «colored» merocyanine forms B and Вх of the indoline spiroantrooxazine (SAO), which was introduced into fluoroplast F-42 matrix from supercritical carbon dioxide (SC-CO2), depends on the volume content of toluene. Toluene in this medium serves as aromatic electron-donating co-solvent. It is shown that the observed ratios of spiroantrooxazine forms content can be described in the framework of kinetic scheme that assumes the SAO molecules relocation between two phases — SC-CO2 and polymer. The «blue» B form is represented by SAO molecules solvated by toluene and localized near certain matrix fragments. Id est, this form is a part of a triple SAO/F-42/toluene complex. The formation of the «red» colored Вх form is due to the coordination of non-solvated SAO molecules penetrating into the matrix from SC-CO2 in the nearest environment of matrix F-42 polymer fragments.

2014, №4

pp. 32-41

Articles

Key words: regeneration, active aluminum oxide catalyst, supercritical carbon dioxide, activity, selectivity

The nature of compounds that inactivate active aluminum oxide catalyst is studied. The results of catalyst regeneration using pure and modified with polar additive (2% wt. DMSO) supercritical carbon dioxide are presented.

2014, №4

pp. 42-52

Articles

Key words: carbon dioxide, cellulose, nitrocellulose, nitration, relative permittivity, dinitrogen pentoxide, nitric acid, supercritical drying

Static relative permittivity of liquid carbon dioxide solutions of dinitrogen pentoxide and its mixtures with nitric, acetic or trifluoroacetic acids is measured. Procedure for nitration of cellulose acquired from various natural sources (wood, linen, hemp, cotton) by mixtures of dinitrogen pentoxide and 100% nitric acid in carbon dioxide medium is developed. Supercritical drying technique is implemented for dehydration of wet nitrocellulose.

2014, №4

pp. 53-60

Articles

Key words: molecular separation, supercritical fluids, thermodiffusion column

The process of separation of carbon dioxide and hexafluorethane mixture in thermodiffusion column under supercritical conditions is studied. It is shown experimentally that the separation efficiency of thermodiffusion column increases when passing from gas phase to supercritical conditions.

2014, №4

pp. 61-69

Articles

Photoinduced processes in β-diketonates of Ag and Eu, incorporated into SiO2 aerogel matrix by supercritical fluid impregnation

A.O. Rybaltovskii, V.G. Arakcheev, A.N. Bekin, A.F. Danilyuk, V.I. Gerasimova, N.V. Minaev, E.N. Golubeva, O.O. Parenago, V.N. Bagratashvili.

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Key words: supercritical carbon dioxide, β-diketonates of Ag and Eu, silica aerogel, photoluminescence, silver nanoparticles, plasmon resonance

Silica aerogels with embedded b-diketonates of Ag and Eu molecules were obtained by impregnation method using supercritical carbon dioxide (SC-CO2). Impregnation of aerogel with Eu(tta)3 molecules gives photoluminescence properties aerogel. Adsorption of Eu(tta)3 at silica clusters of aerogel pores leads to a strong broadening of the Stark components in the spectrum of its photoluminescence. Impregnation of aerogel with AgFOD molecules and subsequent laser irradiation, causes the formation of silver nanoparticles in a matrix of aerogel, as a result of AgFOD photolysis and subsequent diffusion atomic nanoassembly. The formation of filamentous structures of silver nanoparticles, due to the effects of self-organization caused by self-focusing and laser light channeling in as formed optical waveguide from nanoparticles. The peculiarities of the formation of Ag nanoparticles by laser photolysis of AgFOD in aerogel matrix directly in SC-CO2 medium are discussed.