Solubility in supercritical carbon dioxide of the predominant carotenes of tomato skin

Solubilities in supercritical carbon dioxide of the predominant carotenes in tomato skin were measured. The use of a polymeric C₃₀ RP-HPLC column to analyze the tomato extract made it possible to separate several geometric isomers from each carotene extracted. The Chrastil model was used to assign a solubility equation to each extracted carotene. Different solubility behaviors in supercritical carbon dioxide were shown by carotenes depending on their nature and configuration. The most soluble carotene was all-trans-phytoene and the least soluble was all-trans-lycopene. Significant differences in solubility were observed between the trans and cis isomers of lycopene. The results indicate that a fractionation of the tomato skin carotenes can be achieved by using supercritical CO₂ extraction.     

Viscosities of fatty acids and methylated fatty acids saturated with supercritical carbon dioxide

The viscosities of several types of lipids saturated with supercritical carbon dioxide (SC-CO₂) were measured with a high-pressure capillary viscometer. Oleic acid and linoleic acid were evaluated from 85 to 350 bar at 40 and 60°C. The more SC-CO₂-soluble methylated derivatives of these fatty acids were evaluated from 90 to 170 bar at 40 and 60°C. The complex mixture of anhydrous milk fat (AMF) was evaluated from 100–310 bar at 40°C. The viscosities of the methylated fatty acids saturated with SC-CO₂ decreased between 5 and 10 times when the pressure increased from 1 to 80 bar, followed by a further decrease by a factor of 2 to 3 when the pressure was increased from 80 to 180 bar. The viscosities of the fatty acids and AMF saturated with SC-CO₂ had viscosity reduction similar to the methylated fatty acids between 1 and 80 bar, but they decreased much less between 80 and 350 bar. At constant pressure, the viscosity of the fatty acids and AMF decreased with increasing temperature, whereas the viscosity of the methylated fatty acids increased with increasing temperature. The lipid/SC-CO₂ mixtures were Newtonian, and their viscosities were best interpreted by using the mass concentration of dissolved SC-CO₂ in the lipids and the pure component viscosities.     

Solubility model of arachis hypogea skin oil by modified supercritical carbon dioxide

The main objective of this study was to determine the solubility of peanut (Arachis Hypogea) skin oil using modified supercritical carbon dioxide (SCCO₂). The solubility was measured at pressure ranging from 100 to 300 Bar, temperature of 313 to 328 K, and rate of modifier from 0.075 to 0.225 mL/min. The solubility of extraction was ranging from 1.12 to 7.73 mg/min. The Chrastil, modified Chrastil, Del Valle Aguilera (DVA), Adachi-Lu, and Gordillo as empirical models were tested to fit the experimental data. Solubilities from these models followed the average absolute relative deviations (AARD) from experimental data: Chrastil, modified Chrastil, DVA, Adachi-Lu, and Gordillo with AARD of 8.54%, 8.26%, 19.41%, 9.24%, and 20.62%, respectively. Modified Chrastil model provide the best fit.     

A new method for estimating solubility of fatty acids, esters, and triglycerides in supercritical carbon dioxide

A method to predict solubility of fat compounds (fatty acids, fatty acid esters, and triglycerides) in supercritical CO₂ in the absence of experimental data is presented. The method is based on the idea of group contribution, so only knowledge about the chemical structure of the substance is needed to predict its solubility in CO₂. Chrastil's equation was used to correlate the solubilities of fatty acids, fatty acid esters, and triglycerides in CO₂. The three parameters determined from fitting of the data were calculated. A nonlinear fit routine was used to determine the chemical group contributions to the three parameters. Analysis of the results shows that it is possible to correlate the parameters of Chrastil's equation to molecular groups. The average deviation from the experimental data was 8%.     

超临界二氧化碳染色技术研究进展

概述了超临界二氧化碳染色技术的染色机理,对不同染料的染色工艺条件的研究情况做了分析。阐述了染料研究和混合染料拼色研究的进展情况。对超临界二氧化碳的染色热力学和动力学性研究情况做了论述,对染料在超临界二氧化碳中的溶解度、染料在纤维与超临界CO2间的分配规律、染料在纤维中的扩散行为做了分析论述。对染色设备的国内外进展情况做了分析论述。指出了超临界二氧化碳染色技术产业化应用应解决的关键问题是增强染料的溶解和在纤维中的扩散,以及高压操作下大容积染色釜的研制。     

苯甲酸在含夹带剂的超临界CO2中溶解度的研究

采用流动法研究和测定了苯甲酸在35、50℃下,10.0—30.0MPa范围内,在纯超临界CO2和含醇系列夹带剂的超临界CO2中的溶解度。实验研究表明,醇系列夹带剂的加入均可明显增大苯甲酸的溶解度,但4种醇的增强作用随着碳链的增加而略有减弱。论述了温度、压力对溶解度的影响,并用Sovova方程对实验数据进行了回归。     

Correlation and estimation of solubilities of fatty acids in supercritical carbon dioxide using solution model approach

In this study, solid solubility data of five fatty acids in supercritical carbon dioxide (CO₂) at different temperatures and pressures are correlated using a two-parameter solution model developed from the regular solution model coupled with the Flory⿿Huggins equation. The developed solution model with fewer parameters yields correlated results comparable to those from commonly used semi-empirical equations. In addition, both parameters in the solution model can be further generalized with the chain length of fatty acids and a new predictive solution model is proposed for solubility prediction. The predictive solution model proposed in this study provides better predicted results and yields average deviation in predicted solubilities of 22.1%. To further apply this solution model to other compounds, solid solubility data of three triglycerides in supercritical CO₂ at 313 K are also correlated. After model simplification and generalization, a new predictive solution model for triglycerides is also proposed, which yields average deviation in predicted solubilities of 29.8%. These results demonstrate that the solution model used in this study is applicable for correlation and prediction of solid solubilities of structure-related compounds in supercritical CO₂.     

Concentration of tocopherols from soybean sludge by supercritical carbon dioxide

A supercritical fluid extraction method has been applied to test the feasibility of tocopherol concentration from soybean sludge with carbon dioxide at temperatures and pressures ranging from 35 to 70°C and 200 to 400 bar, respectively. The supercritical solubility of the esterified soybean sludge was over 4–6 times greater than that of the original soybean sludge. By a simple batch-type one-stage method the tocopherols in the esterified soybean sludge could be concentrated up to 40 wt%. The overall results of the present study show that soybean sludge initially containing about 13–14 wt% tocopherols may require a countercurrent multistage column to be highly and effectively concentrated.     

超临界CO2清洗技术

介绍了超临界CO2清洗的工艺及其应用,分析了超临界CO2清洗在技术、经济及环保方面的特点。     

Methanolysis of seed oils in flowing supercritical carbon dioxide

The direct methanolysis of triglycerides in flowing supercritical carbon dioxide by an immobilized lipase is described. The reaction system consists of two syringe pumps for substrate addition and another two syringe pumps for delivering CO₂ at 24.1 MPa. Corn oil is pumped into the carbon dioxide stream at a rate of 4 μL/min, and methanol is pumped at 5 μL/min to yield fatty acid methyl esters (FAME) at >98% conversion. Direct methanolysis of soy flakes gives FAME at similar yields. This combined extraction/reaction is performed at 17.2 MPa and 50°C. The fatty acid profiles obtained for these seed oils matches those obtained by classical chemical synthesis.     

Solubility of fish oil fatty acid ethyl esters in suband supercritical carbon dioxide

Mutual solubilities and K-values of fish oil fatty acid ethyl esters, prepared from sand launce oil, and sub- and supercritical carbon dioxide have been measured in an apparatus originally designed for phase equilibrium, density and gasoil ratio measurements of reservoir fluids. The measurements were performed at pressures from 2 to 22 MPa at temperatures of 283.2, 313.2 and 343.2°K. Experimental temperatures, pressures, solubilities, K-values and densities are reported. The K-values of ethyl myristate, palmitate, oleate, eicosapentaenoate and docosahexaenoate are compared with published experimental binary and/or multicomponent data. Because both vapor and liquid solubilities are reported, such data are applicable in the design of supercritical extraction plants.     

超临界二氧化碳技术的应用进展

超临界流体(SCF)因其具有很多优异特性而广泛应用于各个领域。主要介绍了超临界二氧化碳流体技术在萃取、制备超细颗粒材料、化学反应、酶催化、高分子科学、化学分析以及精密仪器清洗几个领域中的应用进展。     

Solubility of chlorpheniramine maleate in supercritical carbon dioxide

Solubility of chlorpheniramine maleate in supercritical carbon dioxide at different temperatures (308–338 K) and pressures (160–400 bar) is measured using static method coupled with gravimetric method. The measured solubility data demonstrated that the solubility of chlorpheniramine maleate was changed between 1.54 × 10⁻⁵ and 4.26 × 10⁻⁴ based on the mole fraction as the temperature and pressure are changed. The general trend of measured solubility data shows a direct effect of pressure and temperature on the solubility of chlorpheniramine maleate. Finally, the obtained solubilities correlated using four semi-empirical density-based correlations including Mendez Santiago–Teja (MST), Kumar and Johnston (KJ), Bartle et al., and Chrastil models. Although the results of modeling showed that the KJ model leads to the average absolute relative deviation percent (AARD %) of 8.1% which is the lowest AARD %, deviation of other utilized correlations are rather the same.     

Continuous supercritical carbon dioxide processing of palm oil

Crude palm oil was processed by continuous supercritical carbon dioxide. The process reduces the contents of free fatty acids, monoglycerides and diglycerides, certain triglycerides, and some carotenes. The refined palm oil from the process has less than 0.1% free fatty acids, higher carotene content, and low diglycerides. Solubility of palm oil in supercritical carbon dioxide increased with pressure. A co-solvent improves the refining process of palm oil.     

Preparation of molecularly imprinted polymers in supercritical carbon dioxide

Molecularly imprinted polymer nanoparticles were prepared in supercritical carbon dioxide using a noncovalent imprinting approach. In the present work, propranolol was used as a model template, methacrylic acid as a functional monomer, and divinylbenzene as a crosslinker. Under a high dilution condition, the heterogeneous polymerization resulted in discrete crosslinked polymer nanoparticles. Compared with the nonimprinted polymers, the imprinted nanoparticles displayed much higher propranolol uptake in a low polarity organic solvent. The use of a single enantiomer (S)‐propranolol as the template clearly demonstrated that the imprinted binding sites are chiral‐selective, with a cross‐reactivity towards (R)‐propranolol of less than 5%. The overall binding performance of the imprinted nanoparticles was comparable to imprinted polymers prepared in conventional organic solvents. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 2863–2867, 2006     

Lipase-catalyzed glycerolysis of soybean oil in supercritical carbon dioxide

The transesterification of soybean oil with glycerol, 1,2-propanediol, and methanol by an immobilized lipase in flowing supercritical carbon dioxide for the synthesis of monoglycerides is described. A lipase from Candida antarctica was used to catalyze the reaction of soybean oil with glycerol, 1,2-propanediol, ethylene glycol, and methanol. Reactions were performed in supercritical carbon dioxide at a density of 0.72 g/L and at a flow rate of 6 μL/min (expanded gas). The substrates were added at flows ranging from 2.5 to 100 μL/min. Monoglycerides were obtained at up to 87 wt%, and fatty acid methyl esters at nearly 100 wt%. The reactivity of the alcohols paralleled the solubility of the substrate in liquid carbon dioxide. Glycerol has the slowest reaction rate, only 2% of that of methanol.     

An improved micro-extraction cell for supercritical fluid extraction and chromatography of fatty acids

An improved supercritical fluid micro-extraction cell of increased reliability was designed for on-line supercritical fluid extraction and chromatography (SFE/SFC) of food and other lipid-related samples. The key components in the modified cell include a Swagelok stainless steel reducing union with a dual ferrule as the cell, with polyetherether-ketone (PEEK) ferrules and nuts to connect the cell to the control valve. The new cell did not leak under all conditions examined (100–500 atmospheres, 40–80°C), even after numerous extractions (>250). The quantitative performance of the cell was evaluated with fatty acid standard solutions, technical grade fatty acid sources and wheat flour. The percent relative error (%RE) for the fatty acid standards and technical-grade fatty acid samples was ≤6.0% for oleic, linoleic and linolenic acid. The %RE for oleic and linoleic acid in the whole-wheat samples was ≤10%. The results demonstrate that the new extraction cell can be used for quantitative extractions and that the sensitivity of the SFE/SFC technique is excellent. Similar SFE/SFC methods could prove useful in studying the interaction of free fatty acids with various food components such as enzymes, amylose and proteins.     

Acylation of glucose catalysed by lipases in supercritical carbon dioxide

The acylation of glucose with lauric acid in a reaction catalysed by two Candida lipases and a Mucor miehei lipase in supercritical carbon dioxide (SCCO₂) was investigated. A linear dependence of the reaction rate on enzyme concentration was observed. Studies on the effect of temperature on enzyme activity showed that Candida antarctica lipase remains stable at temperatures as high as 70°C. Non-immobilised Candida rugosa lipase was found to have a temperature optimum at 60°C. The acylation reaction rate depended on the initial water activity of both substrates and enzyme; the optimum was 0·75 for Candida antarctica lipase, 0·53 for Candida rugosa lipase, and between 0·3 and 0·5 for Mucor miehei lipase. Candida rugosa lipase was most active at a molar ratio of sugar: acyl donor of 1: 3, while the optimum ratio was found to increase to 1: 6 when the reaction was catalysed by Candida antarctica and Mucor miehei lipases. © 1998 SCI     

用超临界二氧化碳法制备超强吸水剂

以N，N’-亚甲基双丙烯酰胺(BIS)为交联剂，研究了疏水性单体丙烯酸十八酯(OA)与亲水性单体丙烯酸(AA)在超临界二氧化碳中的聚合反应，制备了超强吸水剂。结果表明，65℃、压力大于13MPa时，制备的产物都为白色固体粉末。用超临界二氧化碳萃取技术可以对产物进行纯化，50℃、20MPa下，产物经超临界二氧化碳萃取2次后纯度可大于95％，4次后单体残留率为0．28％。该超强吸水剂的吸水率有一定下降，然而保水率却得到提高。     

PP/超临界CO2连续挤出发泡成型

以超临界CO2为发泡剂,在连续挤出发泡过程中研究了超临界CO2用量对高熔体强度均聚聚丙烯(PP)发泡成型过程的影响.随着超临界CO2用量的增加,发泡挤出机口模压力降低,试样发泡倍率降低,泡孔尺寸变小,泡孔密度提高.在w(CO2)为3%,5%时,得到发泡倍率最高为13左右的PP发泡材料.w(CO2)为7%,发泡温度为12...