新疆木垒香阿魏成分提取及分析

超临界CO2流体萃取、溶剂二氯甲烷和水蒸气蒸馏等不同方法对新疆木垒香阿魏根进行提取,气相色谱-质谱联用分析比较其中成分;从该种植物中共得到42个峰,其中鉴定出28个化合物;三种方法中超临界CO2流体萃取方法优于传统方法,三者中主要挥发性成分愈创木醇的含量都很高。     

The ultrasonic-enhanced factor of mass-transfer coefficient in the supercritical carbon dioxide extraction

Based on several hypotheses about the process of supercritical carbon dioxide extraction, the onflow around the solute granule is figured out by the Navier-Stocks equation. In combination with the Higbie’s solute infiltration model, the link between the mass-transfer coefficient and the velocity of flow is found. The mass-transfer coefficient with the ultrasonical effect is compared with that without the ultrasonical effect, and then a new parameter named the ultrasonic-enhanced factor of mass-transfer coefficient is brought forward, which describes the mathematical model of the supercritical carbon dioxide extraction process enhanced by ultrasonic. The model gives out the relationships among the ultrasonical power, the ultrasonical frequency, the radius of solute granule and the ultrasonic-enhanced factor of mass-transfer coefficient. The results calculated by this model fit well with the experimental data, including the extraction of Coix Lacryma-jobi Seed Oil (CLSO) and Coix Lacryma-jobi Seed Ester (CLSE) from coix seeds and the extraction of Eicosapentaenoic Acid (EPA) and Docosahexaenoic Acid (DHA) from the alga by means of the ultrasonic-enhanced supercritical carbon dioxide extraction (USFE) and the supercritical carbon dioxide extraction (SFE) respectively. This proves the rationality of the ultrasonic-enhanced factor model. The model provides a theoretical basis for the application of ultrasonic-enhanced supercritical fluid extraction technique. Supported by the Major Program of the National Natural Science Foundation of China (Grant No. 10674048) and the Natural Science Foundation of Guangdong Province (Grant No. 06025714)     

Separation of a molecular mixture in a thermodiffusion column under supercritical conditions

The process of separation of carbon dioxide and hexafluorethane mixture in a thermodiffusion column under supercritical conditions is studied. It is shown experimentally that the separation efficiency of thermodiffusion column increases when passing from the gas phase to supercritical conditions.     

Possible mechanism of oil formation in a flow of supercritical fluid (using carbon dioxide as an example)

An experimental study of the supercritical fluid extraction of the organic substance with carbon dioxide from rock and soil showed that a supercritical (SC) fluid can dissolve, transfer, and accumulate petroleum-like hydrocarbons including relict ones. It was hypothesized that during the supercritical extraction, the dissolution of organic substances is accompanied by their mechanochemical transformation in the micropores and microcracks of the solid. The resulting changes in the composition, structure, and distribution of the individual hydrocarbons are similar to those in petroleum-mother rocks. We can therefore assume that fast mechanochemical transformation of the dispersed organic matter of sedimentary rocks takes place in a flow of a deep supercritical fluid. This, in turn, would allow one to revise the time scale of oil accumulation from millions to possibly hundreds of years.     

微细管内超临界二氧化碳冷却换热研究

本文对超临界二氧化碳在微细管内冷却对流换热进行数值模拟研究,分析不同流动方向和管径大小对超临界二氧化碳对流换热的影响,考察管内局部流体温度、管壁温度以及无量纲温度分布的变化。湍流模型采用低雷诺数YS模型。研究表明,在LPV范围比较大的截面,超临界二氧化碳局部换热系数达到最大值,同时管内传热受流动方向和管径的影响均较大。     

Supercritical Fluid Extraction of Usnic Acid from Lichen of <Emphasis Type="Italic">Cladonia</Emphasis> Genus

The process of carbon dioxide supercritical fluid extraction (SFE) of secondary metabolites from the lichen of Cladonia genus is studied. The yield of solid extract during SFE with carbon dioxide is significantly higher than during the extraction with acetone, ethanol, and petroleum ether on the Soxhlet apparatus. The maximum content of the target component—usnic acid (UA)—in the extract (91%, yield—2.5% of absolutely dry raw material) is obtained under pressure of 35 MPa, temperature 40°C, and duration of the process of 40 min. Introduction of cosolvents (acetone, ethanol, methylene chloride) to carbon dioxide increases the yield of the target product to 3%.     

Evaluation of the Efficiency of Supercritical Carbon Dioxide Extraction for <Emphasis Type="Italic">Pelargonium graveolens</Emphasis> L’Her Essential Oil Production

The optimal conditions (40°С, 16 MPa, process duration of 30 min) for the extraction of Pelargonium graveolens L’Her essential oil using supercritical (SC) carbon dioxide are determined. GC-MS analysis shows higher concentrations of the target components (e.g., citronellol, geraniol) in the product in comparison to the oil obtained using a traditional method (steam distillation). Additional components, such as camphene, sabinene, and others are also present in the product obtained by the extraction with SC-CO₂.     

Some thermodynamic processes of anthracite–carbon dioxide mixture in supercritical fluid state

In the context of the development of the catalyst regeneration procedure via supercritical fluid CO₂ extraction, some thermodynamic properties of the anthracene–carbon dioxide mixture in supercritical fluid state have been studied. Data on anthracene solubility in pure and modified (dimethyl sulfoxide, 5 wt %) supercritical carbon dioxide (SC–CO₂), the heat capacity of anthracene and its mixtures with carbon dioxide, and the heat of solution of anthracene in SC–CO₂ are presented. Anthracene solubility in SC–CO₂ is described satisfactorily using the Peng–Robinson equation of state.     

Supercritical fluid extraction of pesticides from human hair followed by gas chromatography-mass spectrometric analysis

A supercritical fluid extraction process using supercritical carbon dioxide for the isolation of chlororganic and phosphororganic pesticides from human hair is developed. The effect of process parameters (temperature, pressure, duration) on the efficiency of pesticide extraction is studied. The gas chromatography-mass spectrometry technique is used for the quantitative analysis of pesticide concentration in hair.     

Supercritical fluid extraction of rare earth elements,thorium and uranium from monazite concentrate and phosphogypsum using carbon dioxide containing tributyl phosphate and di-(2-ethylhexyl)phosphoric acid

Supercritical fluid extraction (SCFE) using carbon dioxide containing tributyl phosphate (TBP), di-(2-ethylhexyl)phosphoric acid (D2EHPA) and their adducts with HNO₃ is applied for extraction of rare earth elements (REE), thorium (Th) and uranium (U) from monazite concentrate (MC) and phosphogypsum (PG). REE extraction from MC and their separation from Th and U are carried out from the product of MC–Na₂CO₃ baking (MCS), which is obtained under microwave irradiation, after which the phosphates of REE, Th and U present in the MC are converted into their oxides. Up to 50% of REE can be recovered as the adducts of TBP and D2EHPA with HNO₃ from the resulting powdered MCS under SCFE conditions, whereas Th and U remain in the solid phase. After a complete dissolution of the MCS residue in the mixture of 4 M HCl and 0.05 M HF, Th and U are quantitatively extracted using supercritical carbon dioxide (SC CO₂) containing D2EHPA and thus separated from the REE that remain in an acidic solution. The conditions of quantitative isolation of REE, Th and U from PG are determined. The schemes for complex processing of MC and PG aimed at REE recovery and their separation from Th and U are suggested.     

Supercritical fluid extraction of chlorophylls and carotenoids from White Sea algae

The supercritical fluid extraction of chlorophylls and carotenoids from marine algae Fucus vesiculosus and Laminaria digitata with carbon dioxide was studied. Complete extraction of carotenoids with carbon dioxide was achieved at a pressure of 250 atm and a temperature of 80°C after 20 min in the absence of a cosolvent. Extraction of chlorophylls in high contents required the use of a polar co-solvent (ethanol, 10–15 vol %) or extraction time increased to 50–90 min (at a co-solvent consumption of <5 vol %). The proposed method is more express compared with extraction in a Soxhlet apparatus.     

Separation of low-molecular-weight fractions of ultrafine polytetrafluoroethylene with supercritical carbon dioxide

The separation of low-molecular-weight fractions of FORUM® ultrafine polytetrafluoroethylene (UPTFE) in supercritical carbon dioxide (SC-CO₂) was studied under static conditions. The experiments were performed over temperature and pressure ranges of 318–383 K and 10–70 MPa, respectively. Over the entire pressure and temperature ranges covered, a behavior typical of solid substance-SC-CO₂ systems was observed: as the pressure and temperature of the solvent increased, so did the concentrations of low-molecular-weight UPTFE fractions in it. The experimental data were interpreted within the framework of three models establishing a relationship between the solubility of a substance with the supercritical fluid density, those proposed by Chrastil, Bartle, and Mendez-Santiago. The experimental data were closely described by the Bartle and Mendez-Santiago models.     

The radioprotective and prophylactic properties of biologically active substances prepared by supercritical fluid extraction from pine shoots

The radioprotective properties of a substance from pine shoots prepared by supercritical fluid extraction with carbon dioxide were studied for a model of an experimental bone-marrow radiation sickness form. Experiments were performed for white nonlinear mice. The CO₂ extract of pine shoots was shown to possess radioprotective properties. The extract was subjected to pre-clinical tests for Wistar line male rats with respect to its antiatherogenic and antioxidative action in the creation of experimental hyperlipemia.     

Regeneration of the palladium catalyst of acetylene hydrogenation in modified supercritical CO<Subscript>2</Subscript>

The results of the regeneration of the deactivated palladium catalyst of acetylene hydrogenation using supercritical fluid extraction (T = 130°C, P = 250 bar) were reported. The activity of the catalyst regenerated in supercritical carbon dioxide is comparable to the activity of the catalyst regenerated by the conventional procedure.     

Supercritical Fluid Extraction as a Method of Thermochemical Activation of Wood Cell Walls

The thermochemical activation of the lignocarbohydrate matrix by supercritical (SC) fluid extraction was studied. Labile and stable regions of lignocarbohydrate formations distributed in the cell wall were revealed. Changes in the composition and morphology of the wood substance during the treatment were determined. Supercritical fluid extraction with carbon dioxide was shown to be a useful method for selective treatment of the weak H-bonds of the lignocarbohydrate complex to obtain new data on the structure and composition of the wood substance and its components.     

Cold and supercooled water: A novel supercritical-fluid solvent

Peculiar properties of fluid mixtures in the vicinity of the critical point of the pure solvent are commonly used in supercritical-fluid technologies, such as fluid extraction, enhanced oil recovery, supercritical chromatography, and micronization. These properties are linked to critical-point anomalies, in particular, very large compressibility and very low interfacial tension. Water, near its vapor-liquid critical point, as a supercritical solvent, is well studied, in contrast to supercooled water. However, more recently, many scientists have started to believe that deep in supercooled region, not directly accessible to bulk-water experiments, there exists a critical point of liquid-liquid separation (“liquid water polyamorphism”). If the water liquid-liquid critical point exists, the addition of a solute will generate critical lines emanating from the pure-water critical point. The phenomenon would be conceptually similar to what is known near the vapor-liquid critical point and what is commonly exploited in supercritical-fluid science and technology. This new idea has not yet been elaborated. The investigation of aqueous systems below the freezing temperature of pure water would not only shed light on the nature of plausible water polyamorphism, but also could open the way for utilizing cold water as a novel and unusual supercritical-fluid solvent.     

The solubility of synthetic asymmetric allyl disulfides in subcritical and supercritical media

The solubility of two synthetic asymmetric allyl disulfides, allyl 8-quinolyl disulfide and allyl benzothiazol-2-yl disulfide, in subcritical Freon R22 and Freon R410a, as well as supercritical carbon dioxide, at a temperature of 40°C and a pressure of 200 bar is determined by a dynamic flow method. It is shown that Freon R22 is a promising solvent for practical applications of allyl disulfides.     

Oxidative delignification of wood in the supercritical carbon dioxide medium. 4. Acetylization of cellulose in the supercritical carbon dioxide medium

It is shown that cellulose can be acetylated with acetic anhydride in supercritical carbon dioxide in the absence of traditional catalysts, toxic solvents, and dilutants. As substrates, three cellulose samples were tested: sulfite and sulfate cellulose and cellulose obtained by low-temperature delignification in a supercritical carbon dioxide medium. The chemical composition of the cellulose diacetate product is characterized.     

二氧化碳超临界流体的管内对流换热研究

随着自然工质ＣＯ２研究的进一步发展，系统中气体冷却器的换热问题越来越受到人们的重视，这是因为高的换热效率是提高系统ＣＯＰ的重要因素．本文首先阐明了超临界流体换热研究的处理原则和分类方法，并重新定义了ＣＯ２临界区范围．利用修改的 ＢＷＲ方程计算得出了 ＣＯ２临界区的物性变化规律，并分析了获得超临界换热关联式的理论求解方法．最后，建立了超临界ＣＯ２管内冷却过程的数学模型，为求解其换热规律提供了方法和依据．     

直射太阳光红外吸收光谱技术遥测大气中二氧化碳柱浓度

大气中二氧化碳浓度持续增高导致环境和气候变化等问题成为人们关注的焦点. 为了实时遥测二氧化碳气体柱浓度, 研究了一种地基低分辨遥测系统和实时光谱数据反演分析方法. 利用该系统在合肥地区进行了连续观测, 从太阳吸收光谱中实时获取了整层大气透过率. 采用逐线积分非线性最小二乘光谱反演算法, 从整层大气透过率中反演了二氧化碳柱浓度和氧气柱浓度, 并以氧气柱浓度为内标函数获得了二氧化碳干空气柱体积混合比, 精密度优于3%. 将2012年9月25日12时到15时本系统测量的二氧化碳干空气柱体积混合比均值与此时段过境本站点区域的日本温室气体卫星观测结果进行了比较, 两者偏差小于1%.可见, 该系统和方法具有很高的精密度和准确度, 是一种有效的温室气体观测手段. 关键词： 红外吸收光谱技术 遥测 二氧化碳 柱浓度