α-萘乙酸与β-萘酚在含夹带剂超临界CO2中溶解度的研究

采用流动法，以乙醇、丙酮、环己烷为夹带剂，测定了固体溶质α-萘乙酸在超临界CO2中的溶解度，并与相应的β-萘酚的溶解度进行了对比研究。试验结果表明，溶质溶解度随压力的升高而增大；高压下高温萃取有利，低压下低温萃取有利；无论何种夹带剂的加入，均能在一定程度上增加溶质的溶解度，但对于极性溶质，极性夹带剂对其溶解度的提高作用更加显著。     

夹带剂对超临界流体中固体溶解度的作用分析

测定了2-羟基苯甲酸在308.15K和328.15K,10.0-25.0MPa条件下,在含和不含夹带剂的超临界CO2中的溶解度数据;分析了夹带剂对超临界流体中固体溶质溶解度的作用机理,得到选择夹带剂的一般原则。     

苯甲酸在含不同夹带剂的超临界CO2中的溶解度

利用流动法分别测定了苯甲酸在温度308.15, 318.15, 328.15 K、压力范围8.0~23.0 MPa时,在纯超临界CO2及以乙醇、乙酸乙酯、乙二醇为夹带剂的超临界CO2中的溶解度. 研究结果表明,三种夹带剂的加入均可以不同程度地提高苯甲酸的溶解度,其增大幅度为乙醇>乙二醇>乙酸乙酯. 此外还探讨了温度、压力对苯甲酸在超临界CO2中溶解度的影响,以及夹带剂的作用机理,并用Sovova方程对实验数据进行回归,得到了较满意的结果.     

夹带剂性质对超临界二氧化碳萃取的影响

介绍了夹带剂在超临界CO2萃取中的作用和原理，分析了夹带剂分子极性、相对分子质量、分子体积及特殊分子结构等性质对超临界CO2萃取的影响，总结出夹带剂性质对萃取率的变化规律：夹带剂的分子极性越大，溶质在超临界CO2中的溶解度越大；夹带剂的相对分子质量、分子体积的增大，其在超临界CO2中的溶解度减小，萃取率减小；夹带剂中易形成氢键的特殊分子结构，可提高萃取率。     

对羟基苯甲酸甲酯在含夹带剂超临界CO2中溶解度的研究

采用流动法测定了对羟基苯甲酸甲酯在含和不舍夹带剂的超临界CO2中的溶解度,实验所用夹带剂分别为正己烷、乙醇、丙酮及混合夹带剂正己烷 丙酮(摩尔比为1：1),夹带剂的摩尔分数均为0．035。论述了温度、压力和夹带剂对固体溶解度的影响,然后用化学缔合模型关联了实验数据,实验值与计算值吻合良好。     

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。     

固体溶质在含夹带剂超临界流体中的溶解度(Ⅱ)——准液体模型

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准液体模型。结果表明,理论计算值与文献数据和本文实验数据均有较好的吻合。     

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。     

红外光谱测量法研究超临界CO2中夹带剂与溶质的相互作用

利用红外光谱技术研究了在超临界CO₂中加入不同夹带剂时,水杨酸中基团的伸缩振动频率的位移及夹带剂与溶质的相互作用。以乙醇为夹带剂时,水杨酸中C=O基团、O—H基团的伸缩振动频率均向低频方向移动;以丙酮为夹带剂时,水杨酸中C=O基团伸缩振动频率向高频方向移动。研究结果表明：当以乙醇为夹带剂时,水杨酸的溶解度远大于以丙酮为夹带剂时的结果,夹带剂对溶质增溶的作用能力,形成氢键的作用远大于溶剂极性的作用。     

流动法测定固体在超临界二氧化碳中的溶解度

建立了一套流动法测定固体物质在超临界CO2 中溶解度的实验装置。该装置用高压六通阀取样 ,特别适用于测量溶解度较小的固体物质。以萘为溶质 ,在 32 8K时对装置进行了验证 ,实验结果与文献值基本相符。装置的工作温度 0～ 80℃ ,工作压力 0 .1～ 40MPa。     

超临界丙烷分级聚苯乙烯

利用超临界流体的溶剂强度随温度、压力的变化而变化和超临界流体泄压至常压时溶质完全析出的特点,采用超临界丙烷取代常规溶剂对聚苯乙烯进行分级研究,以期柔性地调节操作温度和压力,获得分子量分布较窄的聚合物级分.结果表明,对多分散系数为4.225的聚苯乙烯进行等温超临界分级和等压超临界分级实验能够得到多分散系数分别为1.0～2.0和1.3～2.0的级分.并且发现,压力和温度越高,溶剂的溶解能力越大,分级得到的级分分子量越大.同时,从高聚物溶液理论出发,结合超临界溶液的溶解特性,建立了超临界流体分级高聚物的级分分子量的预测模型.利用实验数据对模型参数优化结果表明,当压力大于25 MPa时,超临界等温分级模型的平均相对误差为5.32％;当温度大于413.15 K时,超临界等压分级模型的平均相对误差为18.03%.     

A comparative evaluation between utilizing SAS supercritical fluid technique and solvent evaporation method in preparation of Azithromycin solid dispersions for dissolution rate enhancement

Azithromycin is a poorly water-soluble drug with a lower dissolution rate which resulted in poor bioavailability after oral administration. The aim of this study was to enhance Azithromycin dissolution by a solid dispersion (SD) using solvent evaporation and supercritical fluid based on solvent-anti-solvent technique. Solid dispersions of Azithromycin were prepared with various concentrations of PEG 6000, Sorbitol and Poloxamer 188, SLS (in ternary systems). All samples were studied for the drug solubility. The formulations were also characterized by IR, DSC, XRD and SEM. The solubility and dissolution rate were remarkably improved in case of most SDs prepared with of PEG 6000 (in binary systems, 1:6 ratio) and both surfactants (ternary systems) compared to the related PMs and pure Azithromycin. But the best result was obtained in the dispersion (Azithromycin:PEG 6000:SLS) with a weight ratio of (1:4:2). SAS–SCF processes were signs of less crystallinity of the drug due to the transformation of its crystalline stat into amorphous state. The analysis of dissolution data indicated that enhanced drug dissolution can be achieved where the SDs obtained in the supercritical fluid process was consisted of PEG 6000 and SLS. The dissolution rate and solubility of Azithromycin improved significantly with PEG 6000 and SLS utilizing SAS-supercritical fluid.     

Purification of Commercial 2,3-Dimethyl Phenol Using Supercritical Fluid Extraction

The commercial value of phenols is often reduced due to the presence of colored impurities. Several conventional techniques have been used for the purification of phenols. However, conventional purification techniques are tedious and make use of hazardous and expensive organic solvents. In this study, we present a new method for purification of an aged-discolored (orange) commercial 2,3-dimethyl phenol (2,3-DMP) reagent (～97%) using supercritical fluid CO₂ (SCF CO₂), as an extraction solvent. A supercritical fluid extraction (SFE)/purification apparatus was constructed and purification of the reagent under different extraction conditions was investigated. Based on the differential solubility of the 2,3-DMP and the impurities in SCF CO₂, the commercial reagent was successfully purified by SFE; the purified 2,3-DMP was a white solid of high purity (>99.5%). The SFE method was also applied to purify a recently purchased batch of 2,3-DMP reagent. We found that the reagent purified by SFE was of a higher quality than a commercially available analytical standard.     

The concept of solid solvent as a processing aid

The concept of solid solvent entails the use of low-molecular weight crystalline materials (LMC) as a processing aid. A LMC as an ideal solid solvent mixed into a polymer is expected to become a solvent for the polymer at high processing temperatures, reducing the melt viscosity and thus enhancing the processability, but to become a nonsolvent for the polymer at low use temperatures precipitating out of the polymer without adversely affecting the properties of the polymer. The feasibility of such a concept was examined using acetanilide as a potential solid solvent for polystyrene (PS) and two ABA-type block copolymers containing PS end blocks. Acetanilide demonstrated the essential features required of a solid solvent supporting the concept of solid solvent. It had a high solubility in PS at high temperatures very effectively reducing the melt viscosity of PS and the block copolymers, and it precipitated out of PS at low temperatures although it had an undesirably high residual solubility. The concept of solid solvent appears to be a viable one.     

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。     

Correlating and Predicting the Solubilities of Solid n-Alkanes in Supercritical Ethane Using Carnahan-Starling-van der Waals Model

The solubilities of some solid n-alkanes in supercritical ethane were correlated and predicted in this paper using the Carnahan-Starling-van der Waals model with a density-dependent parameter of a12. At a given temperature, the linear fit of the parameter of a12 and the density of the supercritical solvent was used for solubility correlation, resulting in an average absolute average relative deviation（AARD） of 8.68%, which was between the values of the semiempirical models and the other compressed gas models used in this article. In the linear fit of the parameter of a12 and the density of the solvent, the regressed slope m and intercept n of the linear fit can be correlated with the carbon atom number of solid n-alkanes and then the solubilities of solid n-alkanes in supercritical ethane can be predicted with the intercept n and slope m. The average AARD in solubility prediction was 26.99%.     

SOLUBILITY OF CO2AND H2S IN A MIXED SOLVENT

Mixed solvents are a combination of chemical and physical solvents and have some advantages over traditional treating solvents for the removal of acid gases from gas streams. The solubility of H₂S and CO₂in a mixed solvent consisting of AMP (2-amino-2-methyl-l-propanol), sulfolane, and water has been measured at 40 and 100°C at partial pressures of the acid gas to 6000 kPa. The solubility in the mixed solvent was compared with the solubility in an aqueous solution of equivalent amine concentration. At solution loadings less than 1 mol acid gas/mol amine, the solubility of the acid gas is lower in the mixed solvent than in the corresponding amine solvent. At higher loadings, the trend is reversed and the solubility is greater in the mixed solvent. The results are rationalized in terms of the effect of the physical solvent component on the chemical reaction and physical vapor-liquid equilibria. The solubility model of Deshmukh and Mather was used to correlate the data.     

对苯二甲酸在水和醋酸体系中相平衡测定与关联

在一定温度下 ,对苯二甲酸、水和醋酸达到固液平衡 ,体系为饱和溶液 ,利用标准氢氧化钠溶液滴定饱和溶液中溶质的含量来测定对苯二甲酸。同时 ,采用热力学模型关联实验数据 ,结果令人满意。     

含麝香体系多元溶液固液平衡研究

测定了酮麝香、二甲苯麝香在单一溶剂和混合溶剂中的溶解度以及酮麝香的中间体 2 ,6 二甲基 4 叔丁基苯乙酮在不同溶剂中的溶解度 ,并且测定了多溶质多溶剂体系的固液平衡 ,采用UNIFAC活度系数法进行以上体系的固液平衡计算 ,计算结果与实验测定结果吻合良好。采用文中提出的方法不仅可以预测多溶质体系在溶液中共同达到饱和时的溶解度 ,而且可以预测部分溶质达到饱和时的溶解度 ,这对于溶液结晶具有重要的指导意义     

SOLUBILITY OF CO2AND H2S IN A MIXED SOLVENT

Mixed solvents are a combination of chemical and physical solvents and have some advantages over traditional treating solvents for the removal of acid gases from gas streams. The solubility of H₂S and CO₂in a mixed solvent consisting of AMP (2-amino-2-methyl-l-propanol), sulfolane, and water has been measured at 40 and 100°C at partial pressures of the acid gas to 6000 kPa. The solubility in the mixed solvent was compared with the solubility in an aqueous solution of equivalent amine concentration. At solution loadings less than 1 mol acid gas/mol amine, the solubility of the acid gas is lower in the mixed solvent than in the corresponding amine solvent. At higher loadings, the trend is reversed and the solubility is greater in the mixed solvent. The results are rationalized in terms of the effect of the physical solvent component on the chemical reaction and physical vapor-liquid equilibria. The solubility model of Deshmukh and Mather was used to correlate the data.