超临界流体中物质溶解度的研究(Ⅰ)

本文分析了超临界流体萃取过程的特点.认为超临界流体的P-V-T行为可采用某种气体状态方程来描述.在分离作用机理上更近于液液萃取过程.提出了其萃取历程的物理化学模式,据此推导了超临界流体中物质溶解度计算公式.通过对此式的剖析和简化,得到了固体及液体纯物质在超临界流体中溶解度的半理论、半经验计算公式.并用文献发表的实验数据对半经验式的适用性进行验算,获得了较满意的结果,平均偏差≤10%.     

若干有机物质在超临界流体中的溶解度

根据溶剂化缔合理论及吸附理论，提出了超临界流体萃取的物理化学机理，据此推导出物质在超临界流体中溶解度的吸附／缔合数学模型.并用文献发表的实验数据对模型的适用性进行验算，获得了较满意的结果.说明提出的物理化学机理比较符合真实超临界流体萃取过程.     

沙棘籽油在超临界CO2中溶解度的测定和关联

对物质在超临界流体中溶解度的计算方法进行了简要评述.重点就Chrastil和del Valle-Aguilera所提出的半经验关联式作了深入分析和比较.认为del Valle-Aguilera公式源于Chrastil公式,但比Chrastil公式在关联实验数据时具有更为广泛的物理含义和适用性.特别对于植物籽油在超临界CO2中的溶解度计算就是成功的例证.最后,采用连续式测量方法, 在10～30MPa和303～323K条件下, 实测了沙棘籽油在超临界CO2中的溶解度数据. 用del Valle-Aguilera公式的形式对实验结果进行关联, 给出了计算参数. 所提出的计算公式, 在上述实验条件范围内, 最大相对误差小于6%.     

松节油在超临界CO_2中的溶解度及对其α-蒎烯和β-蒎烯的分离

<正> 1 引言 物质在超临界流体中具有良好的溶解性能和传质特性。纯物质在超临界流体中溶解度的研究已取得较大进展。但对混合物溶解度研究的报道甚少。 用超临界CO_2提取天然物已有大量文献报道。提取产物的组成和含量随实验条件有很大变化,其变化规律仅能从定性上给予说明。 松节油是由多种化合物组成的混合物,主要含α-蒎烯和-蒎烯等萜烯。由于它们的挥发度等性质相近,若用传统精馏方法需要几十个塔板才能达到分离要求。本文用NOVA-4L超临界萃取装置对其进行分离研究,并考察其变化规律。 2 溶解度的计算公式 谭飞等用超临界萃取的物理化学模型导出了物质在超临界流体中的溶解度,并给出精确度较高的半经验计算公式 (1)     

缔合模型用于超临界萃取溶解度计算

基于在超临界萃取过程中,同时存在超临界流体相－固相相平衡和超临界相缔合反应平衡的假设,提出一一个用于超临界萃取溶解度计算的缔合模型。该模型式用于２７个固体溶质和５个液体溶质在超临界溶剂中溶解度的计算,其平均相对偏差绝大多数体系均小于１０％。     

固体硫在超临界/近临界酸性流体中的溶解度(Ⅱ)热力学模型

将固体硫在超临界/近临界含硫化氢酸性流体中的溶解行为视为超临界流体萃取固体的过程.通过对经典混合规则的修正,将PR状态方程应用于固体硫在纯H_2S、CO_2及CH_4中溶解度数据的关联,并对固体硫在含H_2S酸性流体混合物中的溶解度进行了预测,取得了令人满意的结果.     

超临界CO2萃取的研究进展

超临界CO2流体萃取技术是近年来兴起的一项具有精馏和萃取两过程的高新物质分离精制技术，文章主要通过对各类超临界CO2流体萃取实验的文献报道和实验操作进行分析，对超临界CO2流体革取技术的原理、特点和超临界CO2流体萃取的主要影响因素及其优化方法和经验模型进行了综述。     

溶解度参数法计算超临界流体的溶解度

溶质在超临界流体中的溶解度计算方法有热力学模型和经验公式2种,其中经验公式法形式简单,精度接近甚至高于热力学模型,应用广泛。以往的经验公式多用超临界流体密度来关联溶解度,文中选择以溶解度参数为变量,用3个与温度无关的可调参数,建立了超临界流体溶解度计算的经验公式。计算的11种固体在超临界CO2、乙烷和乙烯中溶解度与实验数据的平均相对误差在10%左右。与密度相比,溶剂与溶质的溶解度参数差更能直观地反映出超临界流体对物质的溶解能力,且具有明确的理论基础,应该引起足够的重视和推广。     

超临界流体中的质量传递原理

本文较详细地论述了超临界流体中质量传递原理,介绍了物质在超临界流体中的传质系数、分子扩散系数的理论关联与实验测定,为超临界萃取传质过程的研究、超临界萃取装置的设计与放大提供参考。     

固体硫在超临界/近临界酸性流体中的溶解度(Ⅱ)热力学模型

将固体硫在超临界/近临界含硫化氢酸性流体中的溶解行为视为超临界流体萃取固体的过程.通过对经典混合规则的修正,将PR状态方程应用于固体硫在纯H_2S、CO_2及CH_4中溶解度数据的关联,并对固体硫在含H_2S酸性流体混合物中的溶解度进行了预测,取得了令人满意的结果.     

固体溶质在含夹带剂超临界流体中的溶解度(Ⅰ)——化学缔合模型

推导和建立了计算固体溶质在含夹带剂超临界流体中溶解度的化学缔合模型。利用文献数据和本文实验数据对该模型的适应性进行了考察,并与文献自身模型的计算精度进行比较,取得了令人满意的结果。     

Measurement and correlation for the solid solubility of non-steroidal anti-inflammatory drugs (NSAIDs) in supercritical carbon dioxide

The solubilities for three non-steroidal anti-inflammatory drugs (NSAIDs) of nabumetone, phenylbutazone and salicylamide in supercritical carbon dioxide were measured in this study using a semi-flow type apparatus. The experimental data were taken at 308.2, 318.2 and 328.2 K, over the pressure range from 10 to 22 MPa. The measured results were then correlated using semi-empirical equation presented by Chrastil, and that presented by Mendez-Santiago and Teja. With optimally fitted parameters, these two equations yielded satisfactory results where the average absolute relative deviation (AARD) was below 7%. Furthermore, the solid solubilities of these three compounds and seven other NSAIDs in supercritical carbon dioxide were correlated by applying the regular solution model coupled with a Flory–Huggins term. The solution model, which has fewer parameters than the semi-empirical equations, yielded comparable correlation results. The parameters in the solution model could be generalized for the specific group of NSAIDs. Finally, the predicted solubilities of 10 NSAIDs in supercritical carbon dioxide were demonstrated to be reliable.     

超临界流体萃取植物中液态组分溶解度的研究

分析了超临界流体（ＳＣＦ）萃取植物中液态组分过程的特点；推导出计算植物中液态组分在ＳＣＦ中溶解的渗透－缔合模型，并就文献发表的实验数据对模型的适用性进行验算，获得较满意的结果。     

非淹没性低速圆射流特性研究

介绍了射流的基本概念、射流的分类和圆射流断裂理论。结合韦伯和列维奇半经验计算公式,在不同射流速度下,对两种孔径的孔口(d0=2mm和3.4mm)进行了非淹没性圆射流特性研究,并做了射流断裂长度的测定。通过实验值和半经验计算值的相互比较,结果显示,在较慢的射流速度下,用韦伯给出的半经验公式计算出的射流断裂长度值和实验值较接近。而在速度稍大一些时,用列维奇给出的公式计算出的射流长度值和实测值吻合得较好。     

超临界流体萃取的平衡溶解度

由溶剂化缔合观点,推导出了计算难挥发物质在超临界流体(SCF)中平衡溶解度的缔合模型.利用文献数据对缔合模型的适用性进行了考察,得到了较满意的结果.以缔合模型为基础,对SCF的溶解能力及其随诸因素影响的变化规律进行了分析和讨论,由此得出的一些推论均能和实验现象一致.     

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.     

Supercritical Fluid Extraction of Triglycerides

Abstract

The demand for natural products has resulted in considerable interest in supercritical fluid (SCF) technology. The advantages of using SCFs as extraction solvents have been well documented. The ease of solute-solvent separation, low toxicity, and the ability to vary the solvent power make the use of SCFs attractive to the food industry, in particular in the area of triglyceride extraction. Recent material published has been primarily concerned with triglyceride extraction using supercritical (SC) carbon dioxide. The data published suggests limited solubilities (1–3 wt%) with the operating pressures in the vicinity of 300–500 bar, which will entail high capital and operating costs. Investigations carried out using SC propane as a solvent have indicated substantially higher loadings at much lower pressures. This is attributed to the similar chemical nature of the solute and the solvent. It is anticipated that triglycerides can be fractionated using SC propane on the basis of chain length and degree of unsaturation. In this paper the potential of using SC propane as a solvent for the extraction of triglycerides is discussed.     

Modelisation Of Micropollutant Removal In Drinking Water Treatment By Ozonation Or Advanced Oxidation Processes (O3/H2O2)

A simulation program is described, tested and used, to predict micropollutant removal in an ozonation bubble tower with or without hydrogen peroxide addition. To compute the removal efficiency, we need to know the chemical reactivity between organic compounds and oxidant species (molecular ozone and hydroxyl radicals), the ozone mass transfer from the gaseous phase to the liquid phase (k_La) and the hydrodynamic model describing the reactor. In this case, we divide the reactor into three parts (water arrival, air arrival and intermediate zones). Each part is modelled using completely stirred tank reactors in series (CSTR).

In each CSTR, the calculation of oxidant concentrations (O₃, H₂O₂) is made through mass balance equations and a semi-empirical formula which gives hydroxyl radical concentrations as a function both of ozone concentration and the main characteristics of the water to be treated (pH, TOC, alkalinity). Another semi-empirical formula links ozone consumption to the same characteristics.