Cláudio Dariva

Extraction of Grape Seed Oil Using Compressed Carbon Dioxide and Propane: Extraction Yields and Characterization of Free Glycerol Compounds

The main objective of this work was to compare the extraction of grape seed oil with compressed carbon dioxide and propane on the extraction yields and chemical characteristics of free glycerol compounds. The experiments were performed in a laboratory scale unit in the temperature range of 30 to 60 degrees C and pressures from 60 to 254 bar. The results showed that propane is a more suitable solvent for grape seed oil extraction than carbon dioxide, as higher extractions yields and a very fast kinetic of extraction were achieved with this solvent. In relation to compressed carbon dioxide extractions, both temperature and density presented a very pronounced and positive effect on the extraction yield. The oils extracted were analyzed qualitatively and quantitatively with regard to the free glycerol compounds, mainly fatty acids, ethyl, and methyl esters. The results showed that these compounds are present in low concentration in vegetable oil (<3%) and that, in general, samples extracted with propane present a smaller amount of peaks of free glycerol compounds in the oil than samples extracted with carbon dioxide.

Optimization of alkaline transesterification of soybean oil and castor oil for biodiesel production

This article reports experimental data on the production of fatty acid ethyl esters from refined and degummed soybean oil and castor oil using NaOH as catalyst. The variables investigated were temperature (30–70°C), reaction time (1–3 h), catalyst concentration (0.5–1.5 w/wt%), and oil-to-ethanol molar ratio (1:3–1:9). The effects of process variables on the reaction conversion as well as the optimum experimental conditions are presented. The results show that conversions >95% were achieved for all systems investigated. In general, an increase in reaction temperature, reaction time, and in oil-to-ethanol molar ratio led to an enhancement in reaction conversion, whereas an opposite trend was verified with respect to catalyst concentration.

Phase behavior of olive and soybean oils in compressed propane and n-butane

Abstract - 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 70 o C 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. Keywords : Vapor-liquid equilibria; Liquid-liquid equilibria; Triglycerides; Propane; N-butane. INTRODUCTION Triglycerides and their fatty acid esters are important raw materials in many industrial processes. Their transformation provides products with high market values such as monoglycerides, widely used as emulsifiers in the food, cosmetics and pharmaceutical industries (Schmid, 1987; Ranalli and Mattia, 1997; Shiomori et al., 1995; Bhaskar et al., 1993). Furthermore, the transesterification of oil and fats produces a mixture of esters known as biodiesel. Such products have attracted considerable environmental interest in the past few years, mainly due to the low levels of pollutant emitted by user engines. Generally, the oil transformation in industrial scale is commonly accomplished by an acid or base-catalyzed reaction. However, yields reported as well as the quality of the products are usually low (Al Saadi and Jeffreys, 1981). An alternative process for obtaining products of high-grade quality is the use of enzyme-catalyzed reactions in supercritical or compressed solvents. Numerous studies have shown that many reactions can be conducted in compressed liquid or supercritical solvent and, in some cases, rates and selectivities achieved are greater than those obtained in normal liquid or gas phase reactions (Rendon et al., 2001; Oliveira and Oliveira, 2000; Jackson and King, 1997; Savage et al., 1995; King et al., 1987). To conduct such reactions, knowledge of the phase behavior of all components in the compressed solvent is of primary importance for process design optimization and for preventing enzyme inactivation due to the effects of high pressure.

Supercritical fluid extraction of a high-ash Brazilian coal : Extraction with pure ethanol and isopropanol and their aqueous solutions

Abstract The effects of extraction temperature, pressure and addition of water on the liquid yield and on the characteristics of the extracts and residues from supercritical fluid extraction (SCFE) of a high-ash Brazilian mineral coal were experimentally investigated. The experiments were performed in a semi-batch laboratory-scale unit in the coal pyrolysis region 598–698 K at pressures up to 12.5 MPa, using supercritical ethanol and isopropanol as primary solvents. An increase in either temperature or pressure caused an increase in the liquid yield for both the pure alcohols and alcohol-water mixtures, although at the same temperature and pressure, the latter led to a lower liquid yield compared with the pure alcohols. The extracts were characterized by a reliable, non-destructive preparative liquid chromatography method providing eight discrete fractions with well-defined chemical functionality. The amount of the lightest compounds in the extract decreased with increasing pressure, while the opposite trend was observed when the temperature increased. The coal after extraction maintained most of its heating value. Ethanol and isopropanol are compared with regard to both the liquid yield and the gasification reactivity of residual coals.

Kinetics of Enzyme-Catalyzed Alcoholysis of Soybean Oil in n-Hexane

This work investigated the production of fatty acid ethyl esters (FAEEs) from soybean oil using n-hexane as solvent and two commercial lipases as catalysts, Novozym 435 and Lipozyme IM. A Taguchi experimental design was adopted considering the variables temperature (35-65 degrees C), addition of water (0-10 wt/wt%), enzyme (5-20 wt/wt%) concentration, and oil-to-ethanol molar ratio (1:3-1:10). It is shown that complete conversion in FAEE is achieved for some experimental conditions. The effects of process variables on reaction conversion and kinetics of the enzymatic reactions are presented for all experimental conditions investigated in the factorial design.

A kinetic approach for predicting diffusivities in dense fluid mixtures

Abstract In this work, the Enskog solution of the Boltzmann equation coupled with the Weeks–Chandler–Andersen perturbation theory of liquids is shown to be an excellent approach for 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. The approach presented here is based on the smooth hard-sphere theory, in which the coupling factor of the rough hard-sphere theory relating translational and rotational motions is made unity, and using the Speedy correlation which has been proposed as a model of self-diffusion coefficient of hard-sphere fluids. The methodology presented here only makes use of pure component information and density of mixtures affording predictions without any binary adjustable parameters. Since the behavior of mutual-diffusion coefficients in the proximity of a binary critical point is of great interest, calculations were also accomplished in the liquid phase along the gas–liquid boundary when experimental data of both binary vapor–liquid equilibrium and densities of mixture were available.

High-pressure vapor-liquid equilibrium data for CO2-orange peel oil

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.

Pressurized liquid extraction of mate tea leaves

The objective of this work is to investigate the influence of process parameters on the pressurized liquid extraction (PLE) of Ilex paraguariensis leaves. A factorial 2(6-2) experimental design was employed using responses as the extraction yield and the chromatographic profile of the extracts. The extraction time, polarity of solvent, amount of sample, numbers of PLE cycles, flushing volume and extraction temperature were selected as independent variables (factors). Results obtained indicated that the solvent polarity was the most significant variable in the study, while the amount of sample and extraction temperature also showed significant effect. The other variables did not present significant influence in the yield of extraction. GC/MS analysis of the extract enabled the identification of saturated hydrocarbons, fatty acids, fatty acid methyl esters, phytosterols and theobromine in the extracts. Quantitative analysis of four compounds presented in the extracts (caffeine, phytol, vitamin E and squalene) was performed by the GC/MS in the SIM mode.

The effect of temperature, pressure, exposure time, and depressurization rate on lipase activity in SCCO2

We investigated the influence of temperature, pressure, exposure time, and decompression rate on lipase activity in high-pressure CO2 medium. A high-pressure, variable-volume view cell was employed in the experiments, varying the temperature from 30 to 70°C in the pressure range of 70–250 bar at various high-pressure exposure times (60–360 min) and adopting several decompression rates (10–200 kg/[m3·min]). The results obtained show that an increase in temperature and density led to an enhancement of enzyme activity losses while the decompression rates had a weak influence on enzyme inactivation.

Chemical profile and antimicrobial activity of Boldo (Peumus boldus Molina) extracts obtained by compressed carbon dioxide extraction

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.