Solubility of Jatropha and Aquilaria oils in supercritical carbon dioxide at elevated pressures

This study investigated experimental equilibrium solubilities of Jatropha curcas and Aquiliaria crassna oils dissolved in supercritical carbon dioxide at temperatures of 318-338 K and pressures of 20, 25, 30, 35 MPa. The highest solubility of J. curcas and A. crassna oil were 29.8 and 28.4 mg L⁻¹, respectively, at 338 K and 35 MPa. The oil solubilities and the concentration of triglycerides both increased with increasing temperature and pressure. Triglyceride molecules surrounded by carbon dioxide molecules may be proposed since solubilities increased with the flux of supercritical carbon dioxide. The solubility of these two oils linearly increased with the density of supercritical carbon dioxide. Experimental data of the oil solubility were successfully correlated by the Chrastil equation.     

Reactive extraction and in situ esterification of Jatropha curcas L. seeds for the production of biodiesel

Jatropha curcas L. has recently been hailed as the promising feedstock for biodiesel production as it does not compete with food sources. Conventional production of biodiesel from J. curcas L. seeds involve two main processing steps; extraction of oil and subsequent esterification/transesterification to fatty acid methyl esters (FAME). In this study, the feasibility of in situ extraction, esterification and transesterification of J. curcas L. seeds to biodiesel was investigated. It was found that the size of the seed and reaction period effect the yield of FAME and amount of oil extracted significantly. Using seed with size less than 0.355 mm and n-hexane as co-solvent with the following reaction conditions; reaction temperature of 60 °C, reaction period of 24 h, methanol to seed ratio of 7.5 ml/g and 15 wt% of H₂SO₄, the oil extraction efficiency and FAME yield can reached 91.2% and 99.8%, respectively. This single step of reactive extraction process therefore can be a potential route for biodiesel production that reduces processing steps and cost.     

Preparation of activated carbon derived from Jatropha curcas fruit shell by simple thermo-chemical activation and characterization of their physico-chemical properties

High surface area activated carbons were prepared by simple thermo-chemical activation of Jatropha curcas fruit shell with NaOH as a chemical activating agent. The effects of the preparation variables, which were impregnation ratio (NaOH:char), activation temperature and activation time, on the adsorption capacity of iodine and methylene blue solution were investigated. The activated carbon which had the highest iodine and methylene blue numbers was obtained by these conditions as follows: 4:1 (w/w) NaOH to char ratio, 800 °C activation temperature and 120 min activation time. Characterization of the activated carbon obtained was performed by using scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) and nitrogen adsorption isotherm as BET. The results present that the activated carbon possesses a large apparent surface area (S_BET = 1873 m²/g) and high total pore volume (1.312 cm³/g) with average pore size diameter of 28.0 Å.     

Effect of process conditions on the removal of phospholipids from Jatropha curcas oil during the degumming process

This work aims to study the removal of phospholipids from Jatropha oil through a conventional degumming process combined with ultrafiltration membrane separation in a small-scale batch system. The effect of temperature, amount of acid solution added, and speed of centrifugation during the conventional degumming process were analyzed using response surface methodology (RSM). The optimum operating condition was determined to be at 65 °C, with 4 wt% acid solution added and a centrifugation speed of 1600 rpm. After the degumming process, the phospholipid content of Jatropha oil was reduced from 1200 ppm to 60 ppm. This was further reduced to less than 20 ppm by subjecting the oil to ultrafiltration membrane separation. It was found that the entire process not only decreased the phospholipid content of the oil but also improved its fuel properties, especially its kinematic viscosity and carbon residue. The kinematic viscosity was decreased from 30.02 cSt (mm²/s) to 27.20 cSt, while the carbon residue was decreased from 7.8% to 4.0%. Aside from the phospholipid content, the other two properties mentioned above were also considered to be important in the use of pure plant oil as a fuel in diesel engines. Future research could investigate the integration and optimization of the conventional degumming process combined with a membrane separation process.     

Biodiesel production from supercritical carbon dioxide extracted Jatropha oil using subcritical hydrolysis and supercritical methylation

This study investigates supercritical carbon dioxide (SC-CO₂) extraction of triglycerides from powdered Jatropha curcas kernels followed by subcritical hydrolysis and supercritical methylation of the extracted SC-CO₂ oil to obtain a 98.5% purity level of biodiesel. Effects of the reaction temperature, the reaction time and the solvent to feed ratio on free fatty acids in the hydrolyzed oil and fatty acid esters in the methylated oil via two experimental designs were also examined. Supercritical methylation of the hydrolyzed oil following subcritical hydrolysis of the SC-CO₂ extract yielded a methylation reaction conversion of 99%. The activation energy of hydrolysis and trans-esterified reactions were 68.5 and 45.2 kJ/mole, respectively. This study demonstrates that supercritical methylation preceded by subcritical hydrolysis of the SC-CO₂ oil is a feasible two-step process in producing biodiesel from powdered Jatropha kernels.     

Two-step biodiesel production from Jatropha curcas crude oil using SiO2·HF solid catalyst for FFA esterification step

A high quality biodiesel was produced from Mexican Jatropha curcas crude oil (JCCO) by a two step catalyzed process. The free fatty acids (FFA) were first esterified with methanol, catalyzed by a solid catalyst: SiO₂ pretreated with HF. The catalyst showed a high number of Lewis acid surface sites, and no CO₂ or H₂O adsorption activity. This catalyst showed a high FFA esterification activity and high stability. After 30 esterification runs, the catalyst activity remained unchanged. During the second step, the triglycerides present in the JCCO were transesterified with methanol catalyzed by NaOH. The chromatographic analysis of the biodiesel obtained, revealed that the process proposed in this investigation led to a very high quality biodiesel, meeting the international requirements for its utilization as a fuel. The combustion gas emissions of the JCCO biodiesel were studied by FTIR spectroscopy using a laboratory combustor. These preliminary results showed low amounts of aromatic and sulfur containing compounds. However, halogenated compounds and dicyclopentadiene were also detected at the combustor exhaust.     

Supercritical fluid extraction of wormwood (Artemisia absinthium L.)

The objective of the work was to optimize the extraction of wormwood oil by supercritical fluid extraction (SFE) of growth-controlled plant material. Different extraction conditions, two growth techniques and various crops were tested and the evolution of the extracted oil composition was screened chromatographically. A comparison with conventional techniques such as hydrodistillation (HD) or organic solvent extraction (OSE) was also presented. Particularly, six CO₂ densities ranging from 285.0 kg/m³ to 819.5 kg/m³ were studied in the range of 9.0-18.0 MPa and 40-50 °C. A systematic study was carried out with plant material from 2005, while SFE of 2006, 2008 and aeroponically grown crops was performed for comparative purposes. The effect of ethanol as a modifier of the supercritical fluid extraction was also studied. The major compounds found in the SFE extracts as well as in the HD essential oils were Z-epoxyocimene, chrysanthenol and chrysanthenyl acetate. A model based on mass transfer equations, the Sovová model, was successfully applied to correlate the experimental data.     

Supercritical carbon dioxide and solvent extraction of 2-acetyl-1-pyrroline from Pandan leaf: The effect of pre-treatment

Pandan (Pandanus amaryllifolius Roxb.) leaf is a source of natural flavoring widely used in South-east Asia. The major compound contributing to the characteristic flavor of Pandan is 2-acetyl-1-pyrroline (2AP). This highly volatile compound also contributes significantly to the flavor of aromatic rice such as basmati and jasmine rice. As the consumer requirement for use of natural flavors, extraction of components from natural sources has been sought. In this study, supercritical carbon dioxide (SC-CO₂) and solvent extraction of components from Pandan leaves were performed. Experimental parameters included particle size and drying method (oven and freeze drying). Results indicated that the initial value of moisture content and particle size of Pandan leaves had the greatest effect on the total yield and 2AP concentration of the extracts. Almost 80% of water in Pandan leaves can be removed by drying. Yields of supercritical extracts were 10 times lower when compared to the hexane extracts. The total yield of extracts was increased up to 50% with decreasing particle size of Pandan leaves. Extraction of coarsely ground freeze-dried Pandan leaves by SC-CO₂ obtained the highest yield (0.88 ± 0.06%) followed by oven dried (0.38 ± 0.09%) and fresh leaves (0.34 ± 0.01%). The 2AP was identified by GC-MS and analyzed by GC-FID. Supercritical and hexane extracts of pre-treated Pandan leaves were found to have a small quantity of 2AP ranging between 0.04 ± 0.01 and 0.45 ± 0.01 ppm. Grinding pre-treatment was the best method for both SC-CO₂ and hexane extractions while the freeze drying method was the best for SC-CO₂.     

Supercritical carbon dioxide extraction of evening primrose oil

The oil extracted from the seeds ofOenothera biennis L. (evening primrose) is a major commercial source of gamma-linolenic acid, a fatty acid having potential therapeutic value in the treatment of several diseases. This fatty acid is prone to oxidation and thermal rearrangement; therefore, the conventional recovery of the oil via mechanical expression and hexane extraction must be carried out under very mild and controlled conditions. In this study, supercritical fluid extraction with carbon dioxide has been employed as an alternative method to recover evening primrose oil (EPO). Extractions were performed over the pressure range of 20–70 MPa and at temperatures from 40 to 60°C, with a CO₂ mass flow rate of 18 g/min. The experimental data permitted the determination of EPO solubility in supercritical CO₂ at the tested extraction conditions. Supercritical fluid Chromatographic analysis of fractions collected during the extraction showed a subtle shift in the triglyceride composition. Fatty acid methyl ester analysis on similar fractions indicated that the fatty acid content was invariant with respect to extraction time. The mention of firm names or trade products does not imply that they are endorsed or recommended by the U.S. Department of Agriculture over other firms or similar products not mentioned.     

Extraction of phenolic fraction from guava seeds (Psidium guajava L.) using supercritical carbon dioxide and co-solvents

In this work the supercritical fluid extraction (SFE) with carbon dioxide (CO₂) and with ethyl acetate (EtAc) and ethanol (EtOH) as co-solvents was applied to obtain the phenolic fraction from guava seeds (Psidium guajava L.). The extraction was explored at various operating conditions, using 10, 20 and 30 MPa and 40, 50 and 60 °C. The use of EtAc and EtOH as co-solvents in SFE was also studied. The supercritical process was compared with traditional techniques such as Soxhlet extraction using EtAc and EtOH as solvents. The quality of the different extracts, obtained using SFE and Soxhlet methods and different solvents, was evaluated through the antioxidant activity, obtained by the collection methods of scavenging DPPH and bleaching of β-carotene, and also through the total phenolic content (TPC) of the samples, by the Folin-Ciocalteu method. The antioxidant potential indicates the use of ethanol as co-solvent as the best modifier in SFE, used in concentration of 10% (w/w) at 50 °C and 30 MPa. The quality of the extracts obtained by SFE with EtOH varied with the operating conditions of temperature and pressure, with higher values obtained at 10 and 20 MPa for TPC results and also antioxidant methods. The process yield of the phenolic fraction was also evaluated for all the extraction procedures studied (SFE and Soxhlet), with results varying from 0.380 to 1.738% (w/w).     

Supercritical extraction of crude oil by methanol- and ethanol-modified carbon dioxide

The effect of ethanol and methanol cosolvents on the extraction yield and kinetics of crude oil originating from the Halfdan field of the North Sea by supercritical carbon dioxide was investigated across a pressure range of 20–60 MPa under a fixed temperature of 60 °C. Results inform that the pure carbon dioxide recovery varied between 43 and 77% while the recovery of the liquid phase of oil ranged between 22 and 56% across the entire pressure range. Using ethanol- and methanol-modified CO₂, the total recovery yield increased significantly averaging an additional 18.2% and 19.4% respectively when compared to pure carbon dioxide. The ethanol addition improved the recovery of the liquid phase of oil averaging 9.6% while the methanol addition improved it to 7.3% across the entire pressure range.Study of the kinetics of extraction process indicated that heavier fractions were extracted faster with the ethanol- compared to the methanol-modified CO₂. GC–MS TIC chromatographic analysis of the extracted oil fractions showed that the extraction of C₁₉-C₃₀ single carbon number groups with the addition of methanol is more dependent on pressure. Predominantly, ethanol addition was more efficient in extraction of C₁₇-C₃₈ single carbon number groups while methanol contributed more in extraction of C₇-C₉ SCN groups.     

Supercritical carbon dioxide extraction of lipids from Pythium irregulare

Lipids that contain polyunsaturated fatty acids (PUFA) have therapeutic value. PUFA, however, degrade in high-temperature, oxygen-rich conditions typical of conventional hot solvent-extraction and distillation methods. Supercritical CO₂ extraction was chosen as an alternative method to recover these valuable compounds from the lower fungus, Pythium irregulare. Freeze-dried biomass was subjected to an aqueous phase and placed into a flow-through extraction apparatus. Extraction of oil from this biomass showed some success for moisture contents as high as 30% (wet basis). The addition of a novel CO₂-philic surfactant to the wet biomass with moisture contents as high as 95% (wet basis) increased the extraction rate of fungal oil by more than an order of magnitude. For tests with extraction times of 5 to 6 h, data for the diffusion-controlled region were modeled with an analytical solution to Fick’s second law. Equilibrium data were also obtained for the fungal oil at two isotherms (40 and 60°C) over a pressure range of 13.7 to 27.5 MPa.     

Supercritical carbon dioxide extraction ofDimorphotheca pluvialis oil seeds

The possibility of extraction ofDimorphotheca oil with supercritical carbon dioxide is demonstrated in this article. Before extraction, the seeds have to be pretreated to improve extraction yield. Experiments showed that the best pretreatment procedure forDimorphotheca was heating the seeds under reduced pressure to 100°C for 60 min, followed by flaking or milling. To give an impression about the efficiency of the supercritical extraction, a mathematical model has been developed to estimate the overall mass transfer coefficient (A _p K). Also, an empirical relation betweenA _p K and the interstitial velocity has been found. The physical properties of the supercriticalDimorphotheca oil are in good agreement with those of conventionally extracted oil, except for a lower phospholipid content. It is expected that further refining of supercriticalDimorphotheca oil will be marginal.     

超临界二氧化碳萃取咖啡因的研究进展

超临界二氧化碳萃取咖啡因高新技术经历了由理论的提出到工业的应用 ,由间歇法到半连续法生产的发展历程。我国科技工作者利用此项技术创造性地开发了茶叶综合利用方法 ,在提取的不同阶段 ,在超临界流体中添加不同的添加溶剂来提取出茶叶中的咖啡因以及茶叶中富含的茶多酚、芳香精油、嘌呤类生物碱等宝贵成分     

Supercritical carbon dioxide extraction of squalene and tocopherols from amaranth and assessment of extracts antioxidant activity

Squalene and tocopherols are the most important bioactive constituents in lipophilic amaranth fraction. Therefore, developments of processes of isolation of amaranth extracts enriched with these compounds are of interest. In this study the lipophilic fraction of amaranth seeds was extracted by supercritical fluid extraction with carbon dioxide (SCE-CO₂) under different pressure conditions and by adding 2 and 5% of cosolvent ethanol. The yield of extract varied from 1.37 (15 MPa without cosolvent) to 5.12% (55 MPa and 5% of cosolvent). The highest content of unsaponifiables (21.1%) in the extract was at 55 MPa and 5% of cosolvent; at these conditions the yields of tocopherols and squalene from amaranth seeds were 317.3 mg/kg and 0.289 g/100 g, respectively. Tocopherol isomers in amaranth oil were distributed at the approximate ratio of 1(α-T):27(β-T):6.5(γ-T):5(δ-T). The extract was fractionated in the two separators by gradual decrease of the pressure and it was found that the fraction obtained at ambient conditions contained the highest concentration of tocopherols (up to 7.6 mg/g) and squalene (up to 17.9 g/100 g oil). The highest antioxidant activity measured by the L-ORAC assay possessed the fractions with the highest concentrations of squalene and tocopherols and obtained at 15 MPa with pure CO₂ (235.1 μmol TE/g) and 2% of cosolvent (257.6 μmol TE/g).     

二氧化碳超临界萃取乙基香兰素粗制品的研究

采用二氧化碳超临界萃取乙基香兰素粗品,研究萃取压力、萃取温度、萃取时间、流体流量等工艺条件对萃取效率和产品质量的影响.得出最佳工艺条件,采用萃取压力25～30 MPa,萃取温度55～60℃,流体流量5 L/h,萃取5～6 h,萃取效率可以达到95％,可以得到质量分数大于95％的乙基香兰素产品.     

超临界CO2萃取丁香挥发油的实验研究

采用正交实验法对超临界CO2萃取丁香挥发油的条件进行了研究。考察了萃取温度、压力、CO2流量等因素在不同水平下对丁香挥发油提取率的影响。得到了超临界C02萃取丁香挥发油的最佳实验条件：萃取压力30MPa、温度40℃、CO2流量40kg／h和萃取时间80min,得率为20．62％。与水蒸气蒸馏法比较,超临界CO2萃取的收率高,萃取时间短。     

Purification of hydrocarbons from aromatic sulfur compounds by supercritical carbon dioxide extraction

Supercritical carbon dioxide extraction to purify samples of model hydrocarbons (tetralin, decalin, and tetradecane) containing various aromatic sulfur compounds (benzothiophene, dibenzothiophene, and 4,6-dimethydibenzothiophene) was studied. The influence of extraction temperature and pressure was investigated for the extraction from a tetralin-dibenzothiophene system in the range of 293-353 K and 8-15 MPa, and it was found that the amount of tetralin extracted increased with an increase in carbon dioxide density, while the separation factor decreased with an increase in carbon dioxide density. High recovery and high separation factor values for the tetralin-dibenzothiophene system were obtained under 10 MPa at 313 K. Higher separation factor was obtained for tetralin than decalin and tetradecane, containing 4,6-dimethyldibenzothiophene than that containing dibenzothiophene.     

Extracts from pitanga (Eugenia uniflora L.) leaves: Influence of extraction process on antioxidant properties and yield of phenolic compounds

Different extraction processes were employed to extract the polyphenolic compounds from pitanga (Eugenia uniflora L.) leaves: a one-step process using water, ethanol or supercritical CO₂ as solvents, and a two-step process using supercritical CO₂ followed by either water or ethanol. The total polyphenolic compounds, total flavonoids and antioxidant activity were determined in all the extracts obtained. The process performance was evaluated with respect to three variables: global extraction yield, concentration and yield of both polyphenols and flavonoids in the extracts. For the one-step extraction, the results showed that the extraction yield increased with solvent polarity. For the two-step process, the results suggested that water was more efficient in extracting the phenolic compounds from E. uniflora when the matrix was previously extracted with scCO₂. With respect to the antioxidant activity, the ethanolic extracts obtained from both processes, using either the DPPH radical scavenging method or the β-carotene bleaching method, presented high antioxidant activities.