The solubility of betulin in pure and modified supercritical carbon dioxide (SC-CO2) at 313.15–333.15 K and 8.0–30.0 MPa is experimentally studied by the dynamic method. It is found that betulin swells in pure SC-CO2 without being dissolved. The solubility of betulin increases upon the addition of 5

THE PURPOSE. Study of extraction processes of plant raw materials with a wide range of biologically active properties, supercritical carbon dioxide used as a solvent, as well as with the addition of ethanol, used as a co-solvent, to supercritical carbon dioxide in a ratio of 5% to the total consumption at a temperature of 313 K and pressure 30 MPa. METHODS. The study of extraction processes was carried out by the method of supercritical fluid extraction, which is effective and environmentally friendly compared to traditional methods for obtaining extracts. The experimental setup, equipped with two plunger pumps, allowed the implementation of a dynamic extraction method with both supercritical carbon dioxide and carbon dioxide with the addition of ethanol. RESULTS. The final extract yields were obtained for Valeriána officinális, Hypericum, Matricaria and Salvia at a temperature of 313 K and a pressure of 30 MPa using pure carbon dioxide and a carbon dioxide/ethanol mixture as a solvent. Based on the results of experimental data, the dependence of the mass yield of the extract on the extraction time was plotted. This determines the extraction rate of each sample. CONCLUSION. The experimental data obtained indicate that for each of the samples of plant raw materials, the use of supercritical carbon dioxide modified with ethanol in a ratio of 95 and 5%, respectively, leads to an increase in the yield of the extract. This, in turn, leads to a reduction in energy costs when implementing the extraction process using the proposed method on an industrial scale.

Based on the hypothesis of scale invariance (scaling), the review describes the main provisions of the modern nonclassical theory of critical phenomena in pure fluids. A detailed description is given to the main types (parametric and six-term or renormalized Landau expansion) of theoretically substantiated crossover equations of state (EoSs) of pure fluids and their application to describe the anomalous behavior of thermodynamic properties in sub- and supercritical fluids. It is shown that the crossover EoS model covers all the characteristic features of the scaling behavior of the thermodynamic properties of pure fluids in the asymptotic region of the critical point in the form of simple power laws with universal critical exponents and transforms into the classical EoSs (in particular, the Landau expansion) with distance from the critical (fluctuation) region. A detailed comparison is made between the predictions of the crossover EoS model and experimental data on the thermodynamic properties for a representative set of supercritical fluids in a wide range of temperatures and pressures. The crossover EoSs of pure fluids are used to quantitatively estimate the boundary of the region of influence of critical fluctuations on the thermodynamic properties, i.e., to evaluate the contribution of the fluctuation component to the experimentally observed anomalous enhancement of the thermodynamic properties of supercritical fluids. An interpretation of supercritical phase transitions (Widom lines) is given based on the concept of large-scale critical fluctuations and crossover theory. Dynamic crossover phenomena are also considered to describe the influence of fluctuations on the critical enhancement of transport properties (thermal conductivity, thermal diffusivity, and viscosity) in sub- and supercritical fluids.

The isothermal VLE properties ( PTxy relationship) of a binary supercritical (SC) C3H8 3 H 8 + o-toluidine mixture was measured by means of static-analytic method with fluid phase sampling at equilibrium conditions. The measurements were made at three temperatures of (393.15, 433.15, and 473.15) K and pressures up to 10.41 MPa. An experimental VLE apparatus, a high-temperature and high-pressure optical cell, has been used to measure the phase equilibrium properties ( PTxy ) of the binary SC C3H8 3 H 8 + o-toluidine mixture. The combined expanded absolute and relative uncertainties of the temperature, pressure, and the phase concentration measurements at 0.95 confidence level with a coverage factor of k = 2 is estimated at 0.15 K, 0.5 %, 4.2 % (for x ) and 4.8 % (for y ), respectively. The critical curve data, T C- x , P C- x , and P C- T C projections, have been derived based on the measured VLE data. The measured VLE and the derived critical curve data were used to estimate the theoretically ( ) infinity important and physical meaning of Krichevskii parameter, partial derivative P partial derivative x . Thermodynamic (partial molar properties, TCVCV2 infinity, C V C V 2 infinity , H infinity 2 , C infinity P 2 , and distribution equilibrium constant K D ), and microstructural (cluster's size, N infinity exc ) properties of infinite-dilute C3H8 3 H 8 + o-toluidine mixture near the critical point of pure solvent (C3H8) 3 H 8 ) were calculated based on the derived Krichevskii parameter and pure solvent (SC C3H8) 3 H 8 ) properties. CP-PC-SAFT and mg-SAFT equation of state (EoS), with zero interaction parameter, k 12 = 0, for both models (pure prediction models, no adjustable parameters) were successfully applied to the present PTxy phase equilibria for the SC C3H8 3 H 8 + o-toluidine mixture. The present measured VLE data for C3H8 3 H 8 + o-toluidine system along with the reported pure compound properties of pure propane and o-toluidine have been used to examine the predictive capabilities of the theoretically based CP-PC-SAFT and mg-SAFT models of EoS. It was demonstrated that mg-SAFT is superior in predicting VLE of the C3H8 3 H 8 + o-toluidine system with k 12 = 0.

The paper presents the results of an experimental study of the solubility of an ethylene-vinyl acetate copolymer (EVA-113) and nitrile-butadiene rubber (NBR-18) in organic solvents (toluene, chloroform, and dichloromethane) in the temperature range from 308 to 373 K at atmospheric pressure. The codispersion of EVA-113 and NBR-18 polymers has been performed in the pressure range from 8.0 to 25 MPa at temperatures between 313 and 333 K using the solution enhanced dispersion by supercritical fluids (SEDS) method. The crystallization kinetics and phase transformations in the polymer blends, obtained by blending in a melt and using the supercritical SEDS methods (prepared by supercritical CO2), were studied and compared. The effects of the EVA-113/NBR-18 ratio and operating conditions (T and P) on the thermal (heat of fusion) and mechanical (tensile strength and relative elongation) characteristics of obtained polymer blends were studied. It has been illustrated that the use of the SEDS technique with the conventional ratio of components of the EVA-113/NBR-18 blend makes it possible to obtain thermoplastic elastomer whose properties are superior to materials obtained by blending in a melt.

An experimental setup was created to measure the solubility of substances in supercritical carbon dioxide by a dynamic method, including the possibility of adding a cosolvent to the main solvent: CO2. A new technique has been developed for determining the mass amount of supercritical carbon dioxide that has passed during the experiment, which is important in determining solubility. Experimental data on the solubility of diphenyl in supercritical carbon dioxide are obtained, which are in good agreement with the literature data, at various state parameters: temperature and pressure. The experimental setup will make it possible to obtain new experimental data in the future on the solubility of a wide range of substances in supercritical carbon dioxide as well as in supercritical carbon dioxide with various organic cosolvents.

Results are presented from an experimental study of the phase equilibrium (PTxy dependence) of an n-octadecane-propane/n-butane system for three isotherms (403.15, 423.15, 443.15 K) in the 0.89-7.24 MPa range of pressures using a high-pressure optical cell. The PTxy data are used to determine critical parameters of a mixture with identical concentrations of the two phases (x = y at fixed P and T).

The issue of recycling polymers and their waste is quite acute. Basically, polymers are processed and blended by mechanically mixing them in a melt. However, the use of supercritical fluid in the processing and dispersion of polymers and their mixtures has shown its prospects. Previous research has found that polymer mixtures obtained by mixing in solution and then precipitating using supercritical carbon dioxide have increased structural order, and therefore an increased crystallinity degree. In this regard, research has been carried out on the application of the supercritical fluid antisolvent method for the processing of secondary raw materials. It should also be noted that dispersing polymers using the supercritical fluid antisolvent method helps remove impurities and low-molecular-weight thermal degradation products from the polymer. This article presents the results of recycling recycled polycarbonate and polyethylene terephthalate, as well as the possibilities of their joint mixing and dispersion using the supercritical fluid antisolvent method, namely the SEDS method. The kinetics of melting and crystallization of these polymers, as well as their mixtures obtained in the melt and using the SEDS method, were studied. As a result of calorimetric studies, it was established that for all mixtures of waste PET - PC obtained using the SEDS method, the specific heat of fusion exceeds the values for similar mixtures obtained in the melt. SEDS conditions create the best conditions for the crystallization process, up to the crystallization of amorphous polycarbonate and polyethylene terephthalate. The results of a study of the physical and mechanical characteristics of the mixtures under study are presented.

Backgrounds For the design and development of a method utilizing SC C3H8 for the chemical synthesis like the production of active pharma ingredients (pharmaceutical applications) and crop protection agents, it is essential to understand the solubility and other properties of benzylamine as an industrial important compound in the SC C3H8. Methods A high-temperature and high-pressure optical cell has been used to measure the phase equilibrium properties (PTxy) of the binary SC C3H8 + benzylamine mixture. The experimental and modeling studies of the isothermal VLE properties (solubility, PTxy relationship) of benzylamine in the supercritical (SC) C3H8 along the four selected constant temperatures of (393.15, 413.15, 433.15, and 473.15) K over the pressure range from (0.9 to 9.5) MPa have been performed in the present work. Significant Findings It was found the Perturbed-Chain Statistical Association Fluid Theory (PC-SAFT) is less accurate than its Critical Point-based revision (CP-PC-SAFT) in predicting the new VLE data in the C3H8 + benzylamine binary system with k12 = 0. Both models substantially deviate from the bubble point data at pressures below 2 MPa.

This paper presents a new experimental VLE (PTxy) property data of aniline in the near and supercritical CO2 at four selected isotherms of (313.15, 333.15, 353.15, and 443.15) K over the pressure range from (0.8 to 32.4) MPa using a high-temperature and high-pressure (HTHP) optical cell. Samples were taken from both equilibrium phases and analyzed using gravimetric technique. The critical property data (PC−TC) have been estimated based on measured VLE data for SC CO2 +aniline mixture. The PC-SAFT and PR equations of state (EoS) were successfully applied to model the phase equilibrium (PTxy) behavior of CO2 +aniline mixture. The present experimental VLE data and the critical curves behavior predicted from both EoS indicates that the phase diagram of the CO2 +aniline mixture belongs to Type III according to classification Konynenburg and Scott.

The phase behavior of binary systems containing organic components (phenol and acetone) and potential extractants (carbon dioxide and propane–butane mixture), which were proposed to be used in the supercritical state to treat the industrial wastewater from PAO Kazanorgsintez, is analyzed. The phase behavior of the CO2–acetone thermodynamic system in the near-critical region (313 K) is studied using a high-pressure optical cell. In this binary system, various phase states are detected, including areas of critical opalescence and complete miscibility. Supercritical fluid extraction (SFE) is investigated in treating a model aqueous solution of phenol and acetone with the concentration corresponding to industrial wastewater.

In many technological applications the solubility (VLE data) of materials (solid or liquids) in SC CO2 is required. It is essential to understand the solubility and other properties of o-toluidine in the SC CO2 due to their technological importance. This paper presents a new isothermal VLE data for SC CO2 (1)+ o-toluidine (2). Thus, the main purpose of the present work is to experimental study of the VLE properties (solubility, PTxy relationship) of o-toluidine (one of the technologically important compound) in the SC CO2 needs for variety industrial applications. The measurements were made at four selected isotherms of (313.15, 333.15, 353.15, and 373.15) K over the pressure range from (1.24 to 31.44) MPa. A high-temperature and high-pressure optical cell has been used to measure of the phase equilibrium properties (PTxy) of the binary CO2 (1)+ o-toluidine (2) mixture. The combined expanded absolute and relative uncertainty of the temperature, pressure, and the phase concentration measurements at 0.95 confidence level with a coverage factor of k = 2 is estimated at 0.15 K, 0.2 %, and 3 %, respectively. The critical point parameters of the mixture in the PC - TC projection have been estimated using the measured VLE data. The shape of the critical curve behavior indicates that CO2 (1) + o-toluidine (2) mixture belongs to the Type III according to the Konynenburg and Scott classification. PR and PC-SAFT equation of state (EoS) were successfully applied to model the phase equilibria (qualitative point of view) for the SC CO2 (1) + otoluidine (2) mixture at the measured experimental temperatures. From a quantitative point of view, the best choice (among the models used) was PR EoS. The critical curves predicted with PR and PC-SAFT EoS confirmed that the mixture is classified as Type III phase behavior.

С использованием оптической ячейки высокого давления в интервале температур 403-443 К и давлений 5,3-24,5 МПа исследовано фазовое равновесие системы сера-пропан/бутан и установлен V-й тип фазового поведения. Растворимость серы в сверхкритической пропан-бутановой смеси оценена на основе характеристик паровой ветви фазового равновесия системы сера-пропан/бутан и описана с использованием уравнения состояния Пенга-Робинсона в сочетании с правилом комбинирования Мухопадхъяи и Рао. Установлено, что пропан-бутановая смесь в сверхкритическом флюидном состоянии, наряду с хорошими экстракционными свойствами, позволяет осуществить процесс обессеривания товарных углеводоро­дов. Например, снижение давления с 25 до 7 МПа позволяет уменьшить содержание серы в продукте на изотерме 413 К в два раза, а на изотерме 443 К - в 10 раз. The results of an experimental study of the phase equilibrium of the sulfur-propane/butane system carried out in the temperature range 403-443 K and pressure range 5.3-24.5 MРa using a high-pressure optical cell are presented. The V type of phase behavior is established. The solubility of sulfur in a supercritical propane-butane mixture under the above mentioned thermodynamic conditions is estimated based on the characteristics of the vapor branch of the phase equilibrium of the sulfur-propane/butane system and described using the Рeng-Robinson equation of state in combination with the rule of combining Mukhopadhyay and Rao. It has been established that the propane-butane mixture in the SCF state, along with good extraction properties, allows for the desulfurization of commercial hydrocarbons. Reducing the pressure from 25 to 7 MРa makes it possible to reduce the sulfur content at the 413 K isotherm by two times, at the 443 K isotherm by 10 times.

Динамическим методом экспериментально изучена растворимость бетулина в чистом и модифицированном сверхкритическом диоксиде углерода (СК-CO2) при 313,15-333,15 К и 8,0-30,0 МПа. Установлено, что в чистом СК-CO2 происходит набухание бетулина без его растворения. Растворимость бетулина повышается при добавлении 5 %-го этанола в качестве сорастворителя. Установлены давления, отвечающие первой и второй кроссоверным точкам - (7,7-8,3) МПа и (27,1-27,6) МПа, соответственно. Экспериментальные данные описаны с использованием модели, основанной на уравнении состояния Пенга-Робинсона. The results of experimental investigation of betulin solubility in pure and modified supercritical carbon dioxide in the range of temperature (313.15 -333.15 K) and pressure (8.00-30.00 MPa) using the dynamic method are presented. It was found that in pure supercritical carbon dioxide betulin does not dissolve but only swells. The addition of 5 % ethanol as a co-solvent increases the solubility. The pressures corresponding to the first and second crossover points of - (7.7-8.3) MPa and -(27.1-27.6) MPa, respectively, are established in this work. The results of the descri ption of the experimental data using a model based on the Peng-Robinson equation of state are presented.

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.

Представлен анализ фазового поведения бинарных систем, включающих органические компоненты (фенол и ацетон) и потенциальные экстрагенты (диоксид углерода и пропан-бутановая смесь), которые предполагаются использовать в сверхкритическом состоянии для очистки промышленного водного стока ПАО «Казаньоргсинтез». Проведено исследование фазового поведения термодинамической системы «CO2—ацетон» в околокритической области состояния (313 K) с использованием оптической ячейки высокого давления. Зафиксированы различные фазовые состояния, включая области критической опалесценции и безграничного смешивания для этой бинарной системы. Приведены результаты использования метода сверхкритической флюидной экстракции для очистки модельного водного раствора фенола и ацетона с концентрацией, соответствующей промышленному стоку. An analysis of the phase behavior of binary systems that include organic components (phenol and acetone) and potential extractants (carbon dioxide and propane-butane mixture), which are supposed to be used in the supercritical state to treat the industrialwastewater runoff of «Êazanorgsintez» PJSC, is presented. The study of the phase behavior of the thermodynamic system «CO2—acetone» in the near-critical region of the state (313 K) was carried out using a high-pressure optical cell. Various phase states are fixed, including areas of critical opalescence and boundless miscibility for this binary system. The results of using the supercritical fluid extraction method for purification of a model aqueous solution of phenol and acetone with concentrations corresponding to industrial waste are presented.

The experimental solubility data of polyvinyl chloride (PVC) and high-pressure polyethylene (HPPE) in organic solvents (toluene, dichloromethane, and chloroform) at temperatures ranging from 308.15 to 373.15 K at atmospheric pressure are reported in the present paper. The solubility of the polymers (PVC and HPPE) in organic solvents (toluene, dichloromethane, and chloroform) was studied at temperatures between 298 and 373 K. The supercritical SEDS dispersion of PVC and HPPE polymer blends at pressures between 8.0 and 25 MPa and at temperatures from 313 to 333 K are reported in the present work. The kinetics of crystallization and phase transformation in polymer blends obtained by blending in a melt, and using the supercritical SEDS method, have been studied. The effect of the HPPE/PVC ratio on the thermal and mechanical characteristics of the polymer blends has been studied. For all studied polymer blends and pure polymers obtained using the SEDS method, the heat of fusion ΔfusH exceeds the values obtained by blending in the melt by 1.5 to 5) times. The heat of fusion of the obtained polymer blends is higher than the additive value; therefore, the degree of crystallinity is higher, and this effect persists after heat treatment. The relative elongation decreases for all polymer blends, but their tensile strength increases significantly.

This paper presents a new experimental VLE property data in the binary system of carbon dioxide – n-tetradecane at three selected isotherms of 313.15 K, 333.15 K, and 353.15 K in the pressure range from (3.8 to 19.0) MPa. The measurements were made using a high-temperature and high-pressure optical cell. The standard absolute u and relativeur uncertainties of temperature, pressure, concentration measurements are: u(T)=7.5 mK; ur(P)=0.00025; ur(x)=0.015; and ur(y)=0.015. The measured VLE data were used to determine the criticalPC-TC curve data. Based on the derived values of the critical parameters of CO2+n-tetradecane mixture the value (-67.58 MPa) of the Krichevskii parameter has been determined. The predictive capabilities of the perturbed chain-statistical associating fluid theory (PC-SAFT), the critical point-based modification of PC-SAFT (CP-PC-SAFT), and the Enhanced-Predictive-Peng-Robinson-78 (E-PPR78) models were examined.

The paper presents the results of the experimental study of the phase equilibrium of the “CO2 – N-methylpyrrolidone / chloroform” system (the ratio of organic solvents is 50 to 50