庆阳香薷挥发油化学成分的研究

用超临界流体 CO2 (加改性剂 )萃取香薷中的挥发油 ,采用 GC- MS法分析鉴定了挥发油的化学成分。在最佳分析条件下 ,共分离、鉴定出了 4 4种化学成分。其中主要成分为酚类、香薷酮、萜类及其含氧衍生物等     

超声场强化超临界CO2萃取除虫菊酯的初步研究

本文以除虫菊花中的除虫菊酯萃取为对象,研究用超临界CO2对其萃取时,施加超声场对萃取物降解及萃取速率的影响.结果表明,在实验范围内施加超声场(200kHz,200W电功率)没有引起超临界CO2流体"空化",从而没有使易分解组分除虫菊酯降解;施加超声场可以提高除虫菊酯的萃取速率,且对萃取速率的影响比用水为共溶剂强,在实验范围内,萃取优化工艺条件为萃取压力(20MPa);施加超声场(200kHz,200W电功率);萃取温度(40℃);添加共溶剂水(0.5ml水/g干花);CO2流量(2.0L·min-1).     

秦岭德昌香薷不同提取方法挥发油成分分析

采用分析型超临界CO2流体萃取技术(SFE-CO2)与传统水蒸汽蒸馏法(SD)分别提取德昌香薷挥发油,并通过气相色谱-质谱联用技术测定了提取物的化学成分.从中分别鉴定出35个和50个化合物.结果显示:白苏酮、香芹酚、α-石竹烯、石竹烯、柠檬醛、芳樟醇、对薄荷烯醇等是德昌香薷挥发油的主要成分.对比两种不同方法的分析结果可知,超临界萃取法比传统水蒸气蒸馏法能得到更多的极性组分,因而其被广泛应用于中草药的分析.     

不同夹带剂对3种丹参酮超临界CO2流体萃取效果的影响

使用不同夹带剂,用超临界CO₂流体萃取丹参中3种丹参酮,研究不同夹带剂的萃取效果。在优化操作条件下萃取丹参中3种丹参酮,HPLC测定萃取物中3种丹参酮的质量分数。3种夹带剂中,95%（V/V）极性物质乙醇效果最好,其次为丙酮、正辛烷。用超临界CO₂流体萃取丹参中3种丹参酮,为了提高萃取率,须使用极性溶剂乙醇作为夹带剂。     

高精度臭灵丹微量元素含量检测系统设计

为了实现快速、无损、实时检测和分析臭灵丹中微量元素的含量,现对高精度臭灵丹微量元素检测系统进行设计。使用当前方法检测臭灵丹时,无法在保证微量元素活性的条件下提取微量元素。为此,提出一种基于Taguchi的高精度臭灵丹微量元素含量检测系统设计方法。该方法使用日本理学ZSX100型X射线荧光光谱仪采集臭灵丹微量元素光谱,确定微量元素种类,利用超临界萃取技术中的两大技术超临界流体萃取技术和超临界固体萃取技术萃取出臭灵丹中的微量元素,再经过超滤分离法中直线段、曲线段、水平段三个阶段分离出萃取液中微量元素,以ICP-MS法计算出微量元素的含量,达到对臭灵丹中微量元素含量的高精度检测。实验仿真证明,所提方法可以快速、无损、实时检测和分析臭灵丹中微量元素。     

用BWR方程关联CO2在超临界区的PVT数据

通常将高于临界温度和临界压力的物质状态称之为流体状态。由于超临界流体兼有液体和气体的双重性质，具有很强的溶解能力和良好的流动、输运性质。基于这些特性，超临界流体被广泛地应用于食品、医药、生物工程、化工、环保、超临界清洗等诸领域，而在超临界流体中研究和应用最多的体系就是超临界CO2(supercritical carbon dioxide，SCCO2)。     

超临界CO2热力学性质的理论计算

应用BWR方程在温度为310～600 K、压强为75～300 bar范围内拟合的超临界CO2流体状态方程,计算了超临界状态下CO2体系的熵、热容和焓.研究表明,这些热力学函数具有明显的超临界特性;与文献值相比,超临界状态下CO2熵的相对误差小于0 .4%,而定压热容的相对误差稍大,为2.45%(T:330～360 K),其数据为进一步从理论上研究超临界CO2与金属铀表面反应的热力学行为奠定了基础.     

地质样品中有机物的超临界萃取研究

建立了以CO2为超临界流体的超临界萃取地质样品中有机物的分析方法,讨论和优化了超临界萃取条件,测定了茂名油页岩中的n-C13-n-C34,并与索式抽提结果作了对比,该方法测定茂名油页岩中的n-C15-n-C34链烷烃,相对标准偏差为（n=4)4.9%-23.8%,n-C13的相对标准偏差为9．2％（n=4),而传统经黄的索式抽提法测得的n=C15-n-C34链烷烃的相对标准偏差为11．2％－37．7％（n=4),n-C13的相对标准偏差为46．4％（n=4),本法与传统方法相比,具有高效,无热降解,无毒,选择性好,精密度好等优点,可直接用于GC,GC－MS的测定。     

超临界CO2钝化金属铀的理论研究

考察超临界CO2 对金属铀表面的钝化作用.首先计算UC、C、UO2 和超临界CO2 的结构和热力学性质,基于这些性质,应用化学平衡原理计算,计算结果指出,反应U(α) +CO2 (g) UO2 (s) +C(Graphite)的△G°为-149. 8~-632. 0kJ,反应2U(α) +CO2 (g) UO2 (s) +UC(s)的△G°为-725. 1~-730. 2kJ,两者均远小于零,即△G<0,且平衡很接近产物一端UC、C、UO2.同时,已经熟知超临界流体的动力学性质极活泼,所以,产物UC、C和UO2 是很稳定的主要成分.根据所计算的产物分子比可以得到元素计量比为UC0. 65±0. 01O1. 30±0. 01,这显然不代表某种分子,但是,这对XPS分析很有用.     

超临界CO_2萃取板蓝根靛玉红的工艺优化研究

采用正交试验法,对板蓝根靛玉红超临界CO2萃取工艺进行优化。选用萃取温度、萃取压力、萃取时间作为正交试验的3个因素,每个因素选3个水平,以提取物中靛玉红的含量来确定最佳提取条件,并且在最佳条件下确定所加夹带剂的最佳剂量。结果表明最佳工艺为:萃取温度45℃、萃取压力35MPa、萃取时间3h,夹带剂为75%的乙醇200mL。最佳工艺条件下提取靛玉红的得率为4.95μg/g,为传统提取方法的1.6倍。     

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.     

Structural and Parametric Optimization of S–CO2 Nuclear Power Plants

The transition to the use of supercritical carbon dioxide as a working fluid for power generation units will significantly reduce the equipment′s overall dimensions while increasing fuel efficiency and environmental safety. Structural and parametric optimization of S–CO₂ nuclear power plants was carried out to ensure the maximum efficiency of electricity production. Based on the results of mathematical modeling, it was found that the transition to a carbon dioxide working fluid for the nuclear power plant with the BREST–OD–300 reactor leads to an increase of efficiency from 39.8 to 43.1%. Nuclear power plant transition from the Rankine water cycle to the carbon dioxide Brayton cycle with recompression is reasonable at a working fluid temperature above 455 °C due to the carbon dioxide cycle′s more effective regeneration system.     

CARS diagnostics of fluid adsorption and condensation in small mesopores

Coherent anti‐Stokes Raman scattering (CARS) spectroscopy is applied to diagnostics of phase behavior of a fluid in pores of nanoporous glasses. Samples with mean pore radii of 2 and 3.5 nm were filled with compressed carbon dioxide at near‐room temperatures. CARS spectra of the 1388 cm⁻¹ Q‐branch were measured at isothermal compressing in a wide pressure range including the transition from gaseous to condensed state. The spectra show specific transformations caused by fluid adsorption and condensation in nanopores. We have carried out calculations of the spectral profiles based on the phase behavior of carbon dioxide in cylindrical glass nanopores. Phase behavior modeling was performed using thermodynamic concepts of surface adsorption and capillary condensation. A good agreement between experimental spectra and calculations was obtained. The potential of CARS technique for the diagnostics of fluid phase behavior in pores and for the characterization of nanoporous host structure is discussed. Copyright © 2011 John Wiley & Sons, Ltd.     

方解石纳米孔隙内二氧化碳毛细凝聚的分子模拟

在二氧化碳地质封存、增产非常规油气以及孔隙材料表征测量方面,纳米孔隙中二氧化碳相态的准确预测具有重要意义。然而,由于纳米尺度下毛细力、分离压等作用力占据主导因素,流体在孔隙中的相行为与体相流体存在根本不同。已有实验和模拟表明,Kelvin毛细凝聚理论无法预测特征尺度10nm下的,孔隙内流体凝聚压力与体相饱和蒸气压的偏离程度。本文利用分子模拟方法,研究了孔径范围为0.83-8.0nm的方解石纳米孔隙中二氧化碳毛细凝聚。结果表明,微孔(小于2nm)中二氧化碳受吸附层影响,凝聚压力远低于体相饱和蒸气压,介孔(2?50nm)中二氧化碳受壁面影响,凝聚压力仍低于体相饱和蒸气压,且受孔径影响显著,并获得了纳米孔隙中二氧化碳相态随压力的变化规律。     

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。     

Convective instability and mass transport of diffusion layers in a Hele-Shaw geometry

We consider experimentally the instability and mass transport of flow in a Hele-Shaw geometry. In an initially stable configuration, a lighter fluid (water) is located over a heavier fluid (propylene glycol). The fluids mix via diffusion with some regions of the resulting mixture being heavier than either pure fluid. Density-driven convection occurs with downward penetrating dense fingers that transport mass much more effectively than diffusion alone. We investigate the initial instability and the quasisteady state. The convective time and velocity scales, finger width, wave number selection, and normalized mass transport are determined for 6000相似文献   

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%.     

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.     

Supercritical fluid extraction of 1,1-dimethylhydrazine from peaty soils

Supercritical fluid extraction of a highly toxic rocket-fuel component (1,1-dimethylhydrazine, UDMH) from peaty soils with carbon dioxide is proposed as a rapid method of sample preparation for ion-chromatographic analysis. Optimum conditions of extraction have been determined. The efficiency of the UDMH extraction can be improved by basic treatments of the soil sample and by the use of proper additives to SC CO₂ (cosolvents).     

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.