An experimental study of the grinding of lidocaine by the rapid expansion of supercritical solutions (RESS method) was carried out. The experiments were carried out in the pressure range of 10-35 MPa and temperatures of 308-333 K. The analysis of the morphology and size of particles, as well as the effect of the process parameters on them, was carried out. Qualitative and quantitative spectrophotometric analysis was carried out. The dissolution test was carried out in a phosphate buffered saline medium simulating plasma, which showed that the reduction in particle size gave an increased yield of the drug in a shorter period of time compared to the original drug that was not treated. Keywords: supercritical fluid, microparticles, spectrophotometric analysis, lidocaine.

Type II phase behavior is determined in the study of the phase equilibrium of the decalin–carbon dioxide binary system in the 313 and 333 K isotherms in the pressure range of 2–15 MPa using a high-pressure optical cell. The experimental results are described using the Peng–Robinson equation of state.

При исследовании фазового равновесия бинарной системы декалин-диоксид углерода, осуществленного на изотермах 313 и 333 K и в диапазоне давлений 2-15 МПа с использованием оптической ячейки высокого давления, установлен II тип фазового поведения. Экспериментальные результаты описаны с использованием уравнения состояния Пенга-Робинсона. The results of an experimental study of the phase equilibrium of the binary system «decalin-carbon dioxide» carried out on isotherms of 313 and 333 K and in the pressure range of 2-15 MPa using a high-pressure optical cell are presented. I-II type of phase behavior has been established. The experimental results are described using the Peng- Robinson equation of state.

An experimental study of the grinding of lidocaine by the rapid expansion of supercritical solutions (RESS method) was carried out. The experiments were carried out in the pressure range of 10–35 MPa and temperatures of 308–333 K. The analysis of the morphology and size of particles, as well as the effect of the process parameters on them, was carried out. Qualitative and quantitative spectrophotometric analysis was carried out. The dissolution test was carried out in a phosphate buffered saline medium simulating plasma, which showed that the reduction in particle size gave an increased yield of the drug in a shorter period of time compared to the original drug that was not treated.

The paper studies the process of pore formation using supercritical fluid media. A mathematical model of pore formation in polymers in the process of supercritical carbon dioxide decompression has been developed, taking into account fluctuations in the Ornstein-Zernike approximation based on Patel-Teja cubic equation. Calculations and comparison with experimental data are given on the example of pore formation in polystyrene, which showed satisfactory agreement of the theory with experiment. Parameters of the Lennard-Jones pair interaction potential for carbon dioxide in the carbon dioxide-polystyrene system were obtained. The diffusion coefficient of supercritical carbon dioxide in a polymer takes on a different value than the coefficient of self-diffusion of pure carbon dioxide under the same thermodynamic conditions due to a change in the Lenard-Jones potential profile in a polymeric medium. The obtained values of the parameters of the Lennard-Jones equation, namely, the parameters of the intermolecular interaction potential and the maximum value of the attraction energy, make it possible to adequately estimate the value of the diffusion coefficient under given thermodynamic conditions.

The adiabatic expansion of supercritical fluid solutions and solubility in pharmaceutical substance–carbon dioxide systems have been investigated. The solubility and average particle size of pharmaceutical substances depend on thermodynamic and geometric parameters of the process. Experimental data on the solubility of pharmaceutical substances in supercritical carbon dioxide have been gained, and empirical binary molecular interaction parameters for the Peng–Robinson equation have been derived. A numerical solution has been obtained for the unified model of nucleation and particle growth (in the drop theory approximation) in the expansion of a steady-state, two-dimensional, viscous, axisymmetric, compressible, supercritical carbon dioxide–pharmaceutical substance flow in a channel with a constant cross section and in a free jet. The correlation parameter of the condensation function, which characterizes the particle growth kinetics, has been determined.

We present the experimental results on the solubility of supercritical carbon dioxide in polyethylene glycol of molecular weight 4000, namely, the isotherms at T = 313, 323, and 333 K in the pressure range of P = 10–35 MPa. Based on the Sanchez–Lacombe lattice model, the results of solubility are described and the empirical parameters of the binary intermolecular interaction in the system of supercritical CO2-polyethylene glycol 4000 are obtained.

Ibuprofen/polyethylene glycol 4000 and methylparaben/polyethylene glycol 4000 nanostructured composite particles are synthesized from gas-saturated solutions (PGSS, particles from gas saturated solution). The dependences of the mean size of composite particles on pressure, temperature, and the expansion channel diameter are revealed. The studies are conducted in the pressure range of 10 to 30 MPa, at temperatures ranging from 40 to 80°C, and for expansion channel diameters in the range of 200 to 500 μm. The physicochemical properties of the composite particles are investigated using a differential scanning calorimeter and phase analysis is performed by means of X-ray diffraction. The composition of composite particles is determined via mass spectrometric analysis. Chromatography-tandem mass spectrometry with electronic ionization is used for the quantitative analysis of ibuprofen, while mass spectrometry of matrix-assisted laser desorption/ionization (MALDI) is used in the analysis of polyethylene glycol 4000. The dependence of the concentration of components in composite particles on pressure is obtained.

Ansys Fluent. Поток флюида предполагается двухмерным, осесимметричным, стационарным, вязким и сжимаемым.In this paper we propose a mathematical description of the processes of nucleation and growth of particles from a supersaturated solution of fluid and supercooled droplet -based theory of the expanding near the critical point in a channel of constant cross section and a free jet of fluid including the neighborhood of Mach disc. To account for the effect of fluctuations on the processes of hydrodynamics, mass transfer, phase equilibria and nucleation Used crossover equation of state Kiselyov. To find the fields of temperature, pressure, density and velocity of the flow system used by the Navier Stokes equations, which is solved by a software package Ansys Fluent. Fluid flow is assumed two-dimensional, axially symmetric, stationary, viscous and compressible.