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。     

2-萘酚与苯甲酸在含夹带剂的超临界流体中溶解度的研究

在自建的超临界流体溶解度实验装置中，测定了固体溶质2—萘酚、苯甲酸在超临界CO2中的溶解度，实验对该类物质的超临界萃取提供了基础数据。对数据的分析讨论表明，随着压力的升高，物质的溶解度增高；随着温度的升高，溶解度的变化比较复杂，在低于特定压力(转变压力)时，温度升高，溶解度增高；在高于特定压力时，温度升高，溶解度降低；夹带剂可以大大提高固体溶质的溶解度，不同的夹带剂，所起作用大小不同；夹带剂的极性、氢键作用对溶解度的提高起着很重要的作用。     

夹带剂对超临界CO2萃取重结晶岩白菜素的影响

以70%的岩白菜素为原料,采用超临界CO2萃取重结晶岩白菜素,考察了甲醇、乙醇、丙酮和乙酸乙酯4种夹带剂对超临界CO2萃取重结晶岩白菜素的结晶率、纯度、形貌和IR图谱等的作用规律.结果表明,在萃取结晶压力为15 MPa、萃取温度为55℃、萃取时间为50 min、CO2流量为15 L·min-1的条件下,乙醇作夹带剂时重结晶纯化岩白菜素的综合效果最好,结晶率达60%以上、重结晶纯度达92%以上,且能保持晶体的优良晶型和结晶品质,综合评价后优选乙醇为夹带剂.     

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。     

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。     

超临界萃取肉桂中主要成分的研究

以超临界CO2萃取肉桂精油,研究了压力、温度、颗粒度、夹带剂（乙醇）的浓度等对提取效果的影响。结果表明,最佳工艺条件为：萃取压力为10MPa,温度为50℃,颗粒度为60目,夹带剂（乙醇）的浓度为90％。在此条件下,肉桂精油的产率为17．48％。     

超临界CO2流体萃取大黄游离蒽醌的研究

研究了带夹带剂的超临界流体萃取大黄中的五种有效蒽醌类物质(大黄酚、大黄素、芦荟大黄素、大黄酸和大黄素甲醚)的工艺,考察了萃取条件(温度和压力)、CO2流量、萃取时间、夹带剂种类等对大黄游离蒽醌萃取率的影响.通过正交实验对萃取釜条件(萃取压力、温度和夹带剂用量)进行了优化;采用液相色谱对萃取产物进行了分析.结果表明,分离釜的温度和压力、CO2流量等对萃取效率影响较小;最佳工艺条件为静萃取时间为60 min、动萃取时间为30 min、以乙醇作夹带剂、乙醇用量300 mL·(100g大黄)-1、萃取温度45℃、萃取压力45 MPa.在此条件下大黄游离蒽醌的萃取量达1.15%.     

超临界CO2萃取烟草中茄尼醇的工艺研究

以烟草为原料,研究了超临界CO2萃取烟草中茄尼醇的过程。考察了萃取压力、萃取温度、萃取时间、CO2流量以及夹带剂浓度和流量等因素对茄尼醇质量收率的影响,并得到了萃取茄尼醇的适宜工艺条件：萃取压力25-35MPa,萃取温度35～45℃,CO2流量2．0～3．0L·min^-1,夹带剂85％乙醇,夹带剂流量0．25～0．35mL·min^-1,萃取时间2h。     

超临界CO2萃取回收SBA-15中的有机模板剂

在200 mL高压萃取釜内,对含夹带剂的超临界CO2萃取回收SBA-15中有机模板剂P123(EO20PO70EO20)的最佳工艺条件进行了研究,考察了夹带剂种类、萃取温度、萃取压力、夹带剂流量对回收率的影响,确定最佳萃取工艺条件为：甲醇作夹带剂,温度45℃,压力27 MPa,夹带剂流量4 mL/min,萃取时间1.5 h,在此条件下P123回收率可达73.7%. 对不同方法脱除P123后的SBA-15进行了表征,结果表明,含甲醇夹带剂的超临界CO2萃取法是一种高效环保的方法,且得到的SBA-15保留了很好的骨架有序性,不会造成骨架硅羟基脱除,克服了高温焙烧脱除模板剂造成的孔道收缩问题.     

Analysis of cosolvent effect on supercritical carbon dioxide extraction for α-pinene and 1,8-cineole

The solubilities of α-pinene and 1,8-cineole in supercritical carbon dioxide with and without cosolvent were measured by using a circulation type apparatus coupled with an on-line Fourier transform infrared (FT-IR) spectroscope at 323 K and 8.0 MPa. The cosolvents interested in this work were ethanol, water, acetone and hexane. The solubilities were measured under vapor–liquid two phases. The effects of cosolvents on the solubilities and selectivities of α-pinene and 1,8-cineole in supercritical CO₂ were investigated. The selectivities at feed concentration of cosolvent of 0.056 mol L⁻¹ were increased 1.23 times by ethanol and decreased 0.82 times by hexane. Peng–Robinson equation of state with a quadratic mixing rule was used for correlations of the solubilities for α-pinene and 1,8-cineole in supercritical CO₂ with and without cosolvent. The correlated results reproduce the experimental data of cosolvent effects on the solubilities and selectivities of α-pinene and 1,8-cineole in supercritical CO₂.     

Measurements and correlation of effect of cosolvents on the solubilities of complex molecules in supercritical carbon dioxide

A new transparent microscale circulation-type high pressure equilibrium cell with on-line sampling was devised. With this apparatus, experimental solubility of molecularly complex species such as steroids (cholesterol, stigmasterol and ergosterol) and fatty acids (palmitic acid and stearic acid) in supercritical carbon dioxide(sc-C0₂) were measured. Also, to find an appropriate substance for enhancing both the polarity and the solubility power of the SC-CO₂ solvent, we arbitrarily selected three polar substances such as acetone, methanol and water and the effect of these cosolvents on the solubility of solutes in SC-CO₂ are examined. The supercritical phase equilibrium data of solute-cosolvent-sc-CO₂ systems were quantitatively correlated using a new equation of state based on the lattice fluid theory incorporated with the concept of multibody interaction. We found that the addition of tracer amount of acetone or methanol to SC-CO₂ enhances the solubility of all solutes about thirty to sixty times when compared with the case of pure sc-CO₂ However, for the case of cosolvent water, no further enhancement of the solubility of solutes was realized. Also, the versatile fittability of the equation of state proposed in this work was demonstrated with the newly measured ternary supercritical equilibrium data.     

Modelling solubility of solids in supercritical fluids using response surface methodology

A Response Surface Methodology approach to correlate the solubility data of solids in supercritical fluids directly to the pressure and temperature is described. Published data for 2,6‐dimethylnaphthalene, 2,3‐dimethylnaphthalene, phenanthrene and benzoic acid in both supercritical carbon dioxide and supercritical ethylene were correlated by means of quadratic models, with R² statistics greater than 0.99 at more than a 99.9% confidence level. With the developed quadratic models, the solubility for the above‐mentioned solids in both supercritical fluids was predicted with average absolute percentage errors less than 5%. So, this approach to estimate solubility provides a possible guide for saving experimental effort and then giving simple models that could be used for industrial design purposes. © 2000 Society of Chemical Industry     

Dye solubility in supercritical carbon dioxide. Effect of hydrogen bonding with cosolvents

The use of supercritical carbon dioxide is emerging as a potential method for achieving pollution-free dyeing. An important factor in supercritical fluid dyeing is the solubility of the dye in supercritical carbon dioxide. Our measurements show that the solubility of C. I. Disperse Red-60 dye in supercritical carbon dioxide is significantly enhanced upon addition of polar csolvents : ethanol and acetone. The solubility enhancement is attributed to the formation of hydrogen bonds between cosolvent and dye molecules. Observed solubility behavior is correlated using dilute-solution theory with lattice-fluid-hydrogen-bonding model. Needed physical and hydrogen-bonding molecular parameters are estimated using the experimental data.     

Solubility of the silver nitrate in supercritical carbon dioxide with ethanol and ethylene glycol as double cosolvents: Experimental determination and correlation

Solubility of the silver nitrate in the supercritical carbon dioxide containing ethanol and ethylene glycol as double cosolvents was measured under certain pressure and temperature range(10–25 MPa, 323.15–333.15 K). The impact of the pressure and temperature on the solubility was also investigated. Based on the experiment data,a correlation model concerning solid's solubility in supercritical fluids was established by combining the solubility parameter with the thermodynamic equation when a binary interaction parameter and a mixed solvent solubility parameter were defined. Experiments show the solubility of AgNO_3 increases with the pressure at a certain temperature. However, the influence of temperature is related to a pressure defined as the turnover pressure(12.3 MPa). When the pressure is higher(or lower) than this turnover pressure, silver nitrate's solubility shows increasing(or decreasing) trend as the temperature rises. Satisfactory accuracy of our presented model was revealed by comparing experimental data with calculated results.     

Regeneration of an alumopalladium hydrogenation catalyst in the process of supercritical CO<Subscript>2</Subscript> fluid extraction

Using a specially created experimental setup, the crossover character of a change in solubility is determined, and the approximate pressure at the upper crossover point is found (≈19 MPa). The modification of carbon dioxide with chloroform is shown to increase its solubility by 2–2.5 times on average within the above range of conditions. The supercritical CO₂ fluid extraction (SCFE) process is studied as it applies to the regeneration of LD-265 alumopalladium hydrogenation catalyst. Dimethylsulfoxide and ethanol are selected as cosolvents (modifiers). Maximum regeneration efficiency is established at a 5.5–6.5 wt % concentration of cosolvents, and dimethylsulfoxide proves to be a more efficient cosolvent than ethanol. The diene and bromine numbers and styrene and methylcyclopentadiene conversions obtained on catalysts regenerated via SCFE satisfy the requirements for catalytic systems used in the selective hydrogenation of dienes in a benzene–toluene–xylene fraction.     

Modeling of drug solubility in supercritical carbon dioxide using equation of state based on hole theory with molecular surface charge density

Equation of state based on hole theory with molecular surface charge density was developed for the modeling of drug solubility in supercritical carbon dioxide. In the hole theory, the density change of supercritical carbon dioxide can be represented by the number of holes in the system. The molecular interaction energy parameter was estimated using the interactions of segments on the molecular surface given by a quantum calculation using conductor-like screening model. The only one parameter, coordination number around a molecule was fitted to the experimental data of the drug solubility in supercritical carbon dioxide. The solubilities of the eighteen drugs in supercritical carbon dioxide were modeled by the equation of state with the molecular surface charge density. The effect of the molecular pair for the coordination number on the correlated results was investigated. It is found that the results using the fitted parameter of the solute–solute pair coordination number result in the modeling performance better than those of carbon dioxide–solute coordination number. The results of the modeling of drug solubility in supercritical carbon dioxide are compared with the experimental data. The average absolute relative deviation between the experimental and calculated results of the solubility for the drug composed of C, H and O atoms acetylsalicylic acid, benzoic acid, ferulic acid, (S)-naproxen, p-benzoquinone, propyl gallate, salicylic acid and vanillic acid is 0.38 smaller than those for compounds including N, F, I and S atoms, amical-48, benzocaine, caffeine, carbamazepine, (±)-flurbiprofen, methimazole, phenazopyridine, theobromine, theophylline and uracil, 0.59.     

超临界二氧化碳中的甲苯选择性氧化反应

考察了甲苯选择性氧化反应中反应物及产物在超临界二氧化碳中的溶解性质。结果表明,甲苯在超临界二氧化碳中的溶解度较大,在反应条件下能与二氧化碳形成均相;苯甲醇、苯甲醛和苯甲酸在超临界二氧化碳中的溶解度随着物质极性的增强而降低。利用不同产物的溶解性差异,可实现超临界二氧化碳中甲苯的选择性氧化。同时考察了超临界二氧化碳中甲苯选择性氧化反应过程中,反应时间、反应压力、反应温度以及n(甲苯)/n(氧气)对反应选择性的影响。     

Solubility of Disperse Red 82 and modified Disperse Yellow 119 in supercritical carbon dioxide or nitrous oxide with ethanol as a cosolvent

Ethanol was used as a cosolvent to enhance the solubility of disperse dyestuffs in supercritical fluids. In the presence of ethanol, from (1 to 5) mol%, the gas–solid equilibrium data of the Disperse Red 82 and modified Disperse Yellow 119 in supercritical carbon dioxide or nitrous oxide have been measured at temperatures from (353.2 to 393.2) K and pressures from (15.0 to 30.0) MPa. The experimental results show that the solubility increases substantially, up to (9 to 25)-fold, by adding 5 mol% of ethanol to the supercritical fluids. In the presence of cosolvent ethanol, the solubility enhancements in nitrous oxide system are much greater than that in carbon dioxide system for modified Disperse Yellow 119 at the same temperature and pressure. The solubility data were correlated with the Chrastil and the Méndez-Santiago and Teja models. The Méndez-Santiago and Teja model yields slightly better results than Chrastil model.