Abstract In this work, the mutual solubilities of sets of ionic liquids ([CnMIM] [TF2N] (n = 4, 8, 12), [C4PY] [TF2N], [C8MIM] [OTF]) and organic compounds (heptane, o-xylene, toluene, or water) are investigated. The experimental data measured for these systems were used to adjust the binary interaction parameters between their components for the Non-Random Two Liquid (NRTL) model. The results showed that the solubility increased with temperature, with high hygroscopicity (10-1 in terms of mole fraction) of the ILs, low interactions with aliphatic hydrocarbons, high interactions with aromatic hydrocarbons and the presence of a lower critical solution temperature (LCST). In addition, this study is the first to show that [C12MIM] [TF2N] is completely soluble in toluene and ortho-xylene between 273.15 and 373.15 K at 1 bar. The average deviations related to the mole fraction between the experimental and calculated values by the NRTL were less than 2.4%.

AbstractWater-in-oil (W/O) emulsions are complex mixtures generally found in crude oil production in reservoirs and processing equipment. Sedimentation studies of water-oil emulsions enable the analysis of the fluid dynamic behavior concerning separation of this system composed of two immiscible liquids. Gravitational settling was evaluated in this article for a model emulsion system consisting of water and a Brazilian crude oil diluted in a clear mineral oil as organic phase. The effects of water content and temperature were considered in the study of sedimentation velocity of water-oil emulsions. Water contents between 10% and 50 % and temperatures of 25, 40 and 60 ºC were evaluated, and a Richardson-Zaki type correlation was obtained to calculate settling velocities as a function of the process variables investigated. Water contents and average droplet sizes were monitored at different levels in the settling equipment, thus enabling identification of the effect of these variables on the phenomena of sedimentation and coalescence of the emulsions studied. The results showed that the emulsion stability during sedimentation was governed by the emulsion water content, which yielded high settling velocities at low water contents, even when very small droplets were present. A quantitative analysis of the combined effects of drop size and droplet concentration supports the conclusion that a stronger effect is produced by the higher concentration of particles, compared with the relatively smaller effect of increasing the size of the droplets.

Three types of propolis extract were prepared and analyzed with respect to their global extraction yields and with respect to the concentration of the following markers: 3,5-diprenyl-4-hydroxycinnamic acid; 3-prenyl-4-hydroxycinnamic acid; 4-hydroxycinnamic acid and 4-methoxy-3,5,7-trihydroxyflavone. The extract EEP (ethanolic extract of propolis) was obtained by the conventional method from raw propolis using ethanol as solvent. The extracts (SFE) were obtained by supercritical solvent extraction from the raw propolis using supercritical carbon dioxide (sc-CO2), with and without the addition of ethanol as a co-solvent. The fractionated supercritical extracts (FSCE) were obtained by fractionation (extract and raffinate) of the dry EEP with sc-CO2. EEP yields of 39.5% were obtained and maximum global extraction yields were 7.3% for SFE with no co-solvent, 51% for SFE with 15% ethanol and 18% for the FSCE extract fraction. The concentrations of the markers in the different extracts differed as a function of the operational parameters, indicating that the addition of co-solvent and the selectivity of sc-CO2 could be manipulated so as to obtain extracts with the yields and concentrations of interest.

As espécies de Maytenus ilicifolia e Maytenus aquifolia são utilizadas como antiespasmódico, contraceptivo, antiulcerogênico, diurético, cicatrizante e analgésico. A ação antiulcerogênica dos extratos de Maytenus ilicifolia possuem relação com a presença de taninos e com os triterpenos friedelan-3-ona, friedelan-3-ol e friedelin. Este trabalho está focado na determinação do teor de taninos e dos triterpenos friedelan-3-ona, friedelan-3-ol e friedelin em 15 populações nativas de Maytenus ilicifolia distribuídas nas regiões Sul e Centro-Oeste do Brasil. A correlação entre a concentração destes compostos com variáveis ambientais, tais como temperatura média anual (TMA), clima segundo Koeppen, vegetação, geomorfologia, latitude e altitude foi determinada através do emprego da correlação de Pearson. Os resultados mostraram que as variáveis temperatura média anual e clima apresentaram influência significativa ao nível de confiança de 95% sobre a concentração de taninos. O maior teor de taninos foi encontrado na população de Ponta Porã, a qual possui uma temperatura média anual de 23 °C. Para os triterpenos estudados, friedelan-3-ona, friedelan-3-ol e friedelin, não foi evidenciada correlação significativa entre a concentração destes compostos com as variáveis ambientais estudadas.

Maytenus ilicifolia and Maytenus aquifolia species are widely used as a cicatrisation agent, an anti-spasmodic, contraceptive, antiulcerogenic, diuretic and analgesic. Considering the importance of these species in popular medicine, this work is focused on the determination of the chemical content of tannins and the triterpenes friedelan-3-one, friedelan-3-ol and friedelin in 15 native populations of Maytenus ilicifolia distributed in the south and mind-west regions of Brazil. Correlation of the concentration of these compounds with the environmental parameters such as average annual temperature, climate, vegetation, geomorphology, latitude and altitude was determined using Pearson's coefficient. Results showed that average annual temperature and climate have significant effect on tannin content at a 95% confidence level. The highest tannin concentration was found in Ponta Porã population, and for the triterpenes investigated, a significant correlation between their concentrations with the environmental variables studied was not verified.

This work reports high-pressure cloud point data for the quaternary system glycerol + olive oil + n-butane + AOT surfactant. The static synthetic method, using a variable-volume view cell, was employed for obtaining the experimental data at pressures up to 27 MPa. The effects of glycerol/olive oil concentration and surfactant addition on the pressure transition values were evaluated in the temperature range from 303 K to 343 K. For the system investigated, vapor-liquid (VLE), liquid-liquid (LLE) and vapor-liquid-liquid (VLLE) equilibrium were recorded. It was experimentally observed that, at a given temperature and surfactant content, an increase in the concentration of glycerol/oil ratio led to a pronounced increase in the slope of the liquid-liquid coexistence curve. A comparison with results reported for the same system but using propane as solvent showed that much lower pressure transition values are obtained when using n-butane.

This work reports the effects of temperature (20 to 50ºC) and pressure (100 to 250 bar) on the extraction yield, chemical characteristics and antimicrobial activity of extracts of Peumus boldus Molina obtained by compressed carbon dioxide extraction. Results showed that the extraction variables affect the extraction yield and the chemical distribution of the major compounds present in the extracts. The extracts were chemically analyzed with regard to 1,8-cineole, trans-sabinene, pinocarveol, pinocarvone, 4-terpineol, ascaridole, piperitone oxide, limonene dioxide and n-eicosane in a GC/MSD. Antimicrobial tests demonstrated that the high-pressure CO2 extracts had activity against 13 bacteria and that better action was verified with extracts obtained at a lower CO2 extraction density and a higher temperature.

Phase equilibrium calculations at high pressures have been a continuous challenge for scientists and engineers. Traditionally, this task has been performed by solving a system of nonlinear algebraic equations originating from isofugacity equations. The reliability and accuracy of the solutions are strongly dependent on the initial guess, especially due to the fact that the phase equilibrium problems frequently have multiple roots. This work is focused on the application of a subdivision algorithm for thermodynamic calculations at high pressures. The subdivision algorithm consists in the application of successive subdivisions at a given initial interval (rectangle) of variables and a systematic test to verify the existence of roots in each subinterval. If the interval checked passes in the test, then it is retained; otherwise it is discharged. The algorithm was applied for vapor-liquid, solid-fluid and solid-vapor-liquid equilibrium as well as for phase stability calculations for binary and multicomponent systems. The results show that the proposed algorithm was capable of finding all roots of all high-pressure thermodynamic problems investigated, independent of the initial guess used.

The aim of this work is to report the experimental data and thermodynamic modeling of phase equilibrium of binary systems containing soybean and olive oils with propane and n-butane. Phase equilibrium experiments were carried out using the static synthetic method in a high-pressure variable-volume view cell in the temperature range from 30 to 70ºC and varying the solvent overall composition from 5 to 98 wt%. Vapor-liquid, liquid-liquid and vapor-liquid-liquid phase transitions were observed at relatively low pressures. The Peng-Robinson and the SAFT equations of state without any binary interaction parameters were employed in an attempt at representing the phase behavior of the systems. Results show the satisfactory performance of SAFT-EoS in predicting qualitatively all phase transitions reported in this work.

Rapid expansion of supercritical solution (RESS) is a promising technique for microparticle production. The literature points out that the RESS technique can be applied to process a wide range of materials including ceramics, polymers, biopolymers, pharmaceutics, and organic compounds. In order to achieve an adequate understanding of the RESS process, it is necessary to conduct more comprehensive studies involving the hydrodynamic modeling of the fluid flow through the capillary, the phase behavior of a expanding mixture, and also with regard to the microparticle formation mechanism. In this context, this work is focused on the analysis of process hydrodynamic modeling and on phase equilibrium modeling (thermodynamic modeling of supersaturation), with a phase stability test coupled. The Gibbs tangent plane distance for the phase stability test was minimized using the simulated annealing algorithm. The results showed that the thermodynamic variables exert a remarkable effect simulated variables (temperature, velocity, density and degree of supersaturation) for the profile.

The aim of this work was to study the feasibility of simultaneous process of high-pressure extraction and fractionation of lemongrass essential oil using molecular sieves. For this purpose, a high-pressure laboratory-scale extraction unit coupled with a column with four different stationary phases for fractionation: ZSM5 zeolite, MCM-41 mesoporous material, alumina and silica was employed. Additionally, the effect of carbon dioxide extraction variables on the global yield and chemical composition of the essential oil was also studied in a temperature range of 293 to 313 K and a pressure range of 100 to 200 bar. The volatile organic compounds of the extracts were identified by a gas chromatograph coupled with a mass spectrometer detector (GC/MS). The results indicated that the extraction process variables and the stationary phase exerted an effect on both the extraction yield and the chemical composition of the extracts.

Recently, there has been a growing interest in fractionating orange peel oil by the use of supercritical carbon dioxide (SCCO2). However, progress in this area has been hindered by the lack of more comprehensive work concerning the phase equilibrium behavior of the SCCO2-orange peel oil system. In this context, the aim of this work is to provide new phase equilibrium data for this system over a wide range of temperatures and pressures, permitting the construction of coexistence PT-xy curves as well as the P-T diagram. The experiments were performed in a high-pressure variable-volume view cell in the temperature range of 50-70ºC from 70 to 135 atm and in the CO2 mass fraction composition range of 0.35-0.98. Based on the experimental phase equilibrium results, appropriate operating conditions can be set for high-pressure fractionation purposes.

In this work the Enskog solution of the Boltzmann equation, as corrected by Speedy, together with the Weeks-Chandler-Andersen (WCA) perturbation theory of liquids is employed in correlating and predicting self-diffusivities of dense fluids. Afterwards this theory is used to estimate mutual diffusion coefficients of solutes at infinite dilution in sub and supercritical solvents. We have also investigated the behavior of Fick diffusion coefficients in the proximity of a binary vapor-liquid critical point since this subject is of great interest for extraction purposes. The approach presented here, which makes use of a density and temperature dependent hard-sphere diameter, is shown to be excellent for predicting diffusivities in dense pure fluids and fluid mixtures. The calculations involved highly nonideal mixtures as well as systems with high molecular asymmetry. The predicted diffusivities are in good agreement with the experimental data for the pure and binary systems. The methodology proposed here makes only use of pure component information and density of mixtures. The simple algebraic relations are proposed without any binary adjustable parameters and can be readily used for estimating diffusivities in multicomponent mixtures.