Constant Extraction Rate Period Research Articles

Supercritical CO2 extraction of total flavonoids from Iberis amara assisted by ultrasound

Iberis amara is used in herbal medicine where it has been shown to have heterogeneous pharmacological effects. In this study, ultrasound-assisted supercritical CO2 extraction (UASCE) of total flavonoids from Iberis amara was optimized. The maximal total flavonoids content (TFC) was achieved at 25 MPa pressure, 46 °C temperature, 0.34 W/mL ultrasonic energy density, which was 18% higher than that obtained with traditional supercritical CO2 extraction. Furthermore, kinetics study showed that ultrasound primarily improves the extraction rate during constant extraction rate period. High correlation (r = 0.78) exists between TFC and antioxidant activity of extracts. Moreover, HPLC analysis revealed that ultrasound introduction can effectively increase the individual concentrations of interested flavonoids (rutin, kaempferol, quercetin, catechin) in extracts in the range from 16.8% to 45.1%. In conclusion, this study suggests that UASCE is a feasible combined technique to produce flavonoids from Iberis amara on an industrial level as well as for analytical purposes.

Development and validation of a green and sustainable procedure for the preparation of Perilla frutescens extracts

A procedure combining supercritical CO2 and ultrasound-assisted (USC-CO2) extraction was developed to obtain rosmarinic acid (RA)-rich extracts from Perilla frutescens. Based on extraction yields and efficiencies, USC-CO2 was considered the best extraction method among the methods studied for obtaining RA from P. frutescens. The constant extraction rate period and the falling extraction rate period for USC-CO2 extraction of P. frutescens were 45 and 96 min long, respectively, and they were significantly shorter than those of traditional SC-CO2 (TSC-CO2) extraction. Furthermore, mass transfer coefficients were derived using the Sovová model for the fluid and solid phases from USC-CO2 extraction, with values of 9.752 × 10−3 and 4.203 × 10−3 min−1, respectively, which were obviously higher than those for TSC-CO2 extraction. Consequently, the theoretical solubilities of RA in the supercritical solvents used in dynamic USC-CO2 and TSC-CO2 extractions were estimated and found to be well correlated using three density-based models.

Extraction of oil rich in coenzyme Q10 from chicken by-products using supercritical CO2

Supercritical CO2 extraction of oil rich in coenzyme Q10 (CoQ10) from chicken by-products (livers and hearts) was investigated. The effects of pressure, temperature, ethanol concentration and CO2 flow rate on the extraction kinetics of oil and CoQ10 concentration in the oils obtained during the constant extraction rate (CER) and falling extraction rate (FER) periods were evaluated. Chicken liver was a richer source of CoQ10 than hearts. CoQ10 recoveries between 79.3% and 96.1% were achieved. Higher CoQ10 concentrations were obtained during the FER period (7.77 mg/g oil at 15 MPa, 40 °C), but most of the CoQ10 was recovered during the CER period. CoQ10 concentration was low and relatively stable during the first part of the extraction and sharply increased as the FER period approached. Fractional extraction resulted in two oil fractions with lower (1.02 mg/g and recovery of 23.5% of total CoQ10 extracted) and higher CoQ10 (4.20 mg/g with 76.5% recovery) contents.

Extraction of cumaru seed oil using compressed propane as solvent

This study reports the oil extraction from cumaru seeds by compressed propane (CPE). Extractions were performed varying temperature (20, 40, 60 °C), pressure (2, 6, 10 MPa), and average particle size (2, 1.7, 1.0, 0.5 mm). The results were compared respect to coumarin content, total phenolic content, antimicrobial and antioxidant activities. It was obtained that 98 % of the total oil present in the seeds can be recovered at 60 °C, 10 MPa, and 0.5 mm. The fatty acid profile indicated that the oil obtained with CPE is richer in unsaturated fatty acids than samples obtained in Soxhlet extraction with n-hexane. Antimicrobial activity was found against Klebsiella pneumoniae, Staphylococcus aureus, and Escherichia coli. Antioxidant activity increased with the coumarin content and both activities were influenced by the coumarin presence (0.11−0.50 wt%). The results showed that CPE is selective for cumaru oil extraction with low contents of coumarin within the constant extraction rate period.

Modeling of Supercritical CO2 Extraction of Palm Oil and Tocopherols Based on Volumetric Axial Dispersion

This article illustrates an application of the volumetric dispersion model in supercritical carbon dioxide extraction. The objectives were to obtain more insight into the mass transfer mechanisms and to clarify a specific rate-dominating mechanism for kinetics to incorporate with the flow model in the extraction process. Experimental results and predictions from models were calibrated to exhibit the role of axial dispersion. The residual oil in pressed oil-palm fibers was extracted in the first experiment. In the second experiment, α-tocopherol was extracted from palm oil. Two-mechanisms, the extraction of easily accessible solute from damaged cells and diffusion-controlled extraction from intact cells, were unified using a suitable switching function. Axial dispersion played a significant role in the constant extraction-rate period in the first experiment. The α-tocopherol extraction rates confirmed the role of axial dispersion through estimated Peclet numbers between 2.5 and 4.5.

Simulating large scale SFE applied to recover bioactive compounds from papaya seeds

Nowadays, food waste valorization is under intense worldwide investigation. In this framework, bioactive compounds from papaya seeds were recovered by supercritical extraction to evaluate the process variables effect in extraction kinetics. A computational code MSEM(MatLab Simulation Extraction Models) was developed to represent different mass transfer models used to describe extraction curves, with best performance by Sovová’s model. The constant extraction rate period provided the highest phenolic content, confirming the high value of papaya seed as source of bioactive compounds such as benzyl isothiocyanate. Moreover, the scale-up criterion with constant ratios of msolv/M and QCO2/MA between small and large scales was suitable. The MSEM code, validate by the small scale data, was efficiently applied to represent the large scale kinetic curves, and also to predict the kinetics behavior at different conditions, based on small scale parameters, enabling the description of the extraction curves without experimental data.

Influence of the bed geometry on the kinetics of rosemary compounds extraction with supercritical CO2

Bed geometry plays an important role in supercritical fluid extraction kinetics. Thus, the objective of this study was to compare the overall extraction curves (OEC's) of rosemary compounds obtained in two beds of 1L each with different geometries (in terms of height to bed (HB) diameter (DB) ratios, HB/DB). A scale-up study was carried out maintaining the solvent mass to feed mass (S/F) ratio equal for both beds. Other process variables, such as bed porosity, apparent and true densities of the raw material, particle average size, temperature, pressure and time of extraction, were also maintained constant. The kinetic parameters were obtained by fitting the OEC to a spline model. The results revealed differences of mass transfer rates, mass ratios of solute in the fluid phase and yields of extract in the constant extraction rate period. The evaluation of the OEC's and kinetic parameters indicated that the bed with lower HB/DB ratio (HB/DB=2.7) was more favorable for obtaining rosemary extract. The kinetics of extraction of oxygenated monoterpenes (i.e., 1,8-cineole and camphor) and phenolic diterpenes (i.e., carnosic acid) were also different for both bed geometries. These behaviors suggest that the bed geometry presents a pronounced influence in the mass transport properties in supercritical media. Thus, in spite of the scale-up criterion be successful for several botanic matrices such as clove buds, sugarcane residue and grape seeds residue, the criterion applied in this study (maintaining a constant S/F ratio for a given time of extraction) was not suitable for this raw material.

Supercritical fluid extraction of carqueja ( Baccharis trimera) oil: Process parameters and composition profiles

Carqueja ( Baccharis trimer a Less) is a common plant native from South America. In this work, the global yield ( X 0) of carqueja oil, extracted by means of supercritical CO 2 at 30 and 40 °C and from 100 to 300 bar, was investigated. The maximum solvent flow rate employed was 8.33 gCO 2/min, with extraction times up to 6 h. The global yields varied from 0.34 to 2.07% (w/w). Additionally, the supercritical process was compared with the organic solvent extraction in terms of yield and oil composition profile. Carqueja extracts were analyzed by gas chromatography–mass spectrometry (GC–MS) and 14 different components were identified. The mathematical models proposed by Tan and Liou [Tan, C. and Liou, D., 1989, Modeling of desorption at supercritical conditions, AIChE J, 35(6): 1029–1031], Brunner [Brunner, G., 1994, Gas Extraction: An Introduction to Fundamentals of Supercritical Fluids and the Application to Separation Processes (Springer, New York)], Sovová [Sovová, H., 1994, Rate of the vegetable oil extraction with supercritical CO 2. Modelling of extraction curves, Chem Eng Sci, 49(3): 409–414] and Esquível et al. [Esquível, M.M., Bernardo-Gil, M.G. and King, M.B., 1999, Mathematical models for supercritical extraction of olive husk oil, J Supercritical Fluids, 16: 43–58] were used for the description of the kinetic aspects of the supercritical process. The modeled results showed good agreement with experimental data especially for the constant extraction rate period (CER).

Extraction and isolation of indole alkaloids from Tabernaemontana catharinensis A.DC: Technical and economical analysis

In the present work, the technical and economical analysis of extraction and isolation of indole alkaloids from Tabernaemontana catharinensis is presented. The extraction was carried out using supercritical CO 2 as solvent and ethanol as cosolvent (5%, v/v). The global yield isotherms were determined at 35 and 45 °C for pressures of 150–350 bar. The mass transfer rate for the constant extraction rate period (CER), the duration of the CER period, and the mass ratio of solute in the fluid phase at the bed outlet were calculated. The extraction curves were adjusted by Crank, Goto et al. and Esquível et al. models. The economical analysis was carried out considering that the cost of manufacturing can be obtained in terms of the costs of investment, operational labor, raw material, waste treatment and utilities. The higher global yields were obtained at 350 bar (1.30 × 10 −2 and 1.54 × 10 −2 kg/kg, at temperatures of 35 and 45 °C, respectively). The Goto's model was able to quantitatively describe the experimental data. The cost of manufacturing the extracts obtained at 350 bar, 45 °C, using 5% (v/v) of ethanol was US$ 79.35 kg −1 of extract. Using previous experimental data obtained at 300 bar, 55 °C, using 10% of ethanol (v/v), the cost of manufacturing for the fractionation process to obtain a rich alkaloidal fraction (AF) was US$ 440.31 kg −1 of alkaloids.

Global yield isotherms and kinetic of artemisinin extraction from Artemisia annua L leaves using supercritical carbon dioxide

Artemisinin is an effective drug used in the malaria treatment. This drug, present in the Artemisia annua L leaves, was extracted using pressurized CO 2 as solvent. The artemisinin global yields isotherms were determined at 30 and 50 °C with pressures in the range of 75–400 bars. The influences of temperature, pressure, and solvent flow rate on the extraction kinetics were also investigated, using a complete factorial design 2 3 (pressures of 200 and 400 bars, temperature of 30 and 50 °C and CO 2 mass flow rate of 5.5 × 10 −5 and 11.1 × 10 −5 kg CO 2/s). Extracts of A. annua L. leaves were also prepared by hydrodistillation and hexane Soxhlet. The mass transfer coefficients for constant extraction rate period were obtained from the experimental data. The extracts were analyzed by GC-FID and the artemisinin content was determined by the indirect method. The maximum artemisinin global yields were obtained at 30 °C and 150 bar (0.62% dry basis – d.b.) and 50 °C and 300 bar (0.70% d.b.). The extract obtained by hydrodistillation presented no artemisinin and the main compounds presented were camphor, β–caryophyllene, borneol e 1,8-cineol. The hexane Soxhlet artemisinin yield was 0.77% in dry basis. The experimental extraction curves were well fitted by the mathematical models of Sovová and Martinez et al., and by the empirical model.

Supercritical fluid extraction of black pepper ( Piper nigrun L.) essential oil

Fixed bed extraction of black pepper essential oil using supercritical carbon dioxide as a solvent was studied. Composition of the extracted oil was obtained by chromatographic analysis, and solubility of the oil was determined using the dynamic method of extraction. Experiments were conducted at 30°C, 40°C and 50°C and 150, 200 and 300 bar. Solubility varied from 0.09 to 0.15 g oil/g CO 2 and increased with the solvent density. In the extraction curves (mass of oil versus mass of CO 2) it was possible to identify the constant extraction rate period as well as the failing and diffusion rate periods. About 70% of the total oil was extracted during the constant rate period.