聚合物-溶剂-超临界CO2三元体系的相行为

研究了聚合物-超临界二氧化碳二元体系溶解性,并考查了添加共溶剂对溶解性的影响,结果表明,添加共溶剂会大大提高CO2的溶解度.此外,还研究了聚合物-溶剂-超临界二氧化碳三元体系在高压时的相行为, 探讨了组分性质、含量等对温度-压力相图的影响.随着CO2含量的增加,压力-温度相图L-LV（单一液相向液气两相共存）边界线的斜率会出现突变点,发生由L-LV边界线向L-LL（单一液相向液液两相共存）边界线的过渡, 而L-LV边界线对不同聚合物并不敏感.     

辽河减压渣油-正戊烷体系的相态变化特性

利用RUSKA公司无汞PVT装置,对辽河减压渣油-正戊烷体系的相行为进行了实验观察,测定了辽河渣油-正戊烷体系相态变化的边界线,如液-液相分界线、液-液-气三相区分界线等,绘制了体系的p-t相图;在140℃～190℃,1.0MPa～10.0MPa,溶剂质量比为3.0～6.0的条件下,对体系相特性的变化进行了分析和讨论。在实验条件下,辽河渣油-戊烷体系的p-t相图可以划分为四个区域:单一液相区、液-液两相区、液-液-气三相区、气-液两相区;溶剂质量比对由单一液相区转变为液-液两相分相压力的影响显著,溶剂质量比越大,分相压力越大;但溶剂质量比对液-液-气三相区影响不大。确定了辽河渣油-正戊烷体系溶剂脱沥青过程适宜的操作区域。     

Na~+,K~+,Mg~(2+)//Cl~-,SO_4~(2-)-H_2O五元体系15℃介稳相图研究

得到Ｎａ＋,Ｋ＋,Ｍｇ２＋//Ｃｌ－,ＳＯ_４_(２－)－Ｈ２Ｏ五元体系１５℃时的介稳溶解度数据,绘制了该体系１５℃的介稳相图,共有９个为氯化钠所饱和的结晶区域:氯化钾、硫酸钠、钾钠芒硝、软钾镁矾、白钠镁矾、光卤石、七水硫酸镁、六水硫酸镁和水氯镁石．所得１５℃介稳相图和Ｖａｎ'ｔ Ｈｏｆｆ稳定相图比较有较大区别;在１５℃介稳相图中钾镁矾、钾盐镁矾以及五水硫酸镁和四水硫酸镁结晶区域消失,而软钾镁矾结晶区域显著扩大．比较作者所作该五元体系１５℃,２５℃及３５℃介稳相图,发现软钾镁矾(包括钾镁矾)相区以２５℃时最大,３５℃时最小;随温度升高,钾钠芒硝结晶相区依次向ＫＣｌ相区平行移动,导致ＫＣｌ相区缩小,Ｎａ２ＳＯ４相区扩大;随温度升高相应点的钠含量和水含量依次减小．     

墨红花超临界二氧化碳香味萃取成分的色谱－质谱法测定

由墨红花提取的精油或油树脂是优质的天然香料，被广泛用于化妆品和食品工业。超临界ＣＯ２萃取墨红花精油，既可保持很好的香气，又能克服传统的有机溶剂萃取时有残余溶剂的缺点。用气相色谱－质谱联用法对超临界ＣＯ２萃取物与石油醚萃取物中的组成进行了分析比较。色谱条件为：ＯＶ－１０１固定相，氦气，０．２ｍｍ×５０ｍ石英毛细管柱，柱温７０℃２ｍｉｎ，然后以５℃／ｍｉｎ程序升温至２５０℃。超临界萃取条件为５０℃，２１ＭＰａ，ＣＯ２流量为１０ｍＬ。发现超临界萃取物中的成分包括了石油醚萃取物中的多数主要香味成分，但对香味影响较小的、分子量较大的烷烃和烯烃的含量较少。超临界二氧化碳萃取物的香气与鲜花相近。     

浆态相低温甲醇合成用的CuCr／CH3ONa催化体系的反应性能

在液相介质为二甲苯，甲醇或液体石蜡，温度１００～１４０℃，压力３．５～４．７ＭＰａ条件下，使用Ｈ２／ＣＯ＝２的合成气，在１Ｌ搅拌釜内考察了自制的ＣｕＣｒ／ＣＨ３ＯＮａ催化体系的浆态相低温甲醇合成的反应性能，结果表明液相介质以二甲苯为佳，ＣＯ转化率随压力而升高，温度以１２０℃为宜。４４ｈ的连续运转表明以ＣＯ转化率为代表的催化体系的反应性能基本稳定。     

离线超临界流体萃取和气相色谱-红外-质谱联用测定水中有机污染物

利用吸附剂ＧＤＸ－３０１对黄河水中的有机污染物富集并以超临界ＣＯ２脱附后,通过气相色谱、色谱－红外－质谱联用技术对各目标分析物逐一定性,并比较了超临界ＣＯ２萃取和溶剂洗脱的结果。实验表明,在２０ＭＰａ,６０℃,４０ｍｉｎ条件下进行超临界ＣＯ２萃取时的萃取效率和溶剂萃取效率相当或略高。     

SrO－La_2O_3／CaO催化剂表面的碱性和催化行为Ⅰ．CO_2－TPD及进料中CO_2对催化行为的影响

添加ＳｒＯ使Ｌａ２Ｏ３／ＣａＯ催化剂的碱性增强及甲烷氧化偶联反应的Ｃ２产率提高，但反应温度随ＳｒＯ含量增加而升高．反应活性高的ＳｒＯ－Ｌａ２Ｏ３／ＣａＯ催化剂，容易被ＣＯ２中毒．催化剂失活的主要原因是表面活性位被碳酸盐覆盖．催化剂失活之前，反应气中添加ＣＯ２可抑制产物中ＣＯ２的生成，提高Ｃ２产率     

超临界CO_2诱导相转化法制备聚苯乙烯膜及膜体系的相图计算

以甲苯为溶剂,利用超临界CO_2诱导相转化法制备了多孔非对称聚苯乙烯膜.通过扫描电镜对膜结构进行了表征,探讨了不同温度、压力和铸膜液中聚苯乙烯浓度对膜形态、孔径分布及膜孔隙率的影响;同时,基于Tompa扩展的Flory-Huggins聚合物溶液理论计算了聚苯乙烯/超临界CO_2/甲苯铸膜体系的三元相图.研究表明,在温度为35~65℃、压力为8~16 MPa及聚合物质量分数为15%~35%条件下,制备的聚苯乙烯膜截面呈胞腔状孔结构,孔隙率为53.54%~84.67%,且孔隙率随温度、压力和聚苯乙烯浓度均呈现出先增大后减小的趋势.相图计算结果表明,温度对体系双节线位置的改变影响较小,而压力对其影响相对较大.     

Sm_2O_3－CeO_2－CUO三元系固线下相关系及电子型超导体Sm_（2－x

用Ｘ射线衍射法测定了Ｓｍ２Ｏ３－ＣｅＯ２－ＣｕＯ三元系固线下相关系，样品是在空气气氛１０００℃烧结的。该体系含有一个三元固溶体Ｓｍ２－ｘＣｅｘＣｕＯ４－ｙ，２个三相共存区和３个两相共存区，测定了Ｓｍ２－ｘ·ＣｅｘＣｕＯ４－ｙ固溶体的固溶限（ｘ＝０．２０），氧含量和超导电性，讨论了晶体结构和氧含量对超导电性的影响。     

墨红花超临界二氧化碳香味萃取成分的色谱－质谱法测定

 由墨红花提取的精油或油树脂是优质的天然香料，被广泛用于化妆品和食品工业。超临界ＣＯ２萃取墨红花精油，既可保持很好的香气，又能克服传统的有机溶剂萃取时有残余溶剂的缺点。用气相色谱－质谱联用法对超临界ＣＯ２萃取物与石油醚萃取物中的组成进行了分析比较。色谱条件为：ＯＶ－１０１固定相，氦气，０．２ｍｍ×５０ｍ石英毛细管柱，柱温７０℃２ｍｉｎ，然后以５℃／ｍｉｎ程序升温至２５０℃。超临界萃取条件为５０℃，２１ＭＰａ，ＣＯ２流量为１０ｍＬ。     

Improving carbon dioxide solubility in ionic liquids

Previously we showed that CO2 could be used to extract organic molecules from ionic liquids without contamination of the ionic liquid. Consequently a number of other groups demonstrated that ionic liquid/CO2 biphasic systems could be used for homogeneously catalyzed reactions. Large differences in the solubility of various gases in ionic liquids present the possibility of using them for gas separations. More recently we and others have shown that the presence of CO2 increases the solubility of other gases that are poorly soluble in the ionic liquid phase. Therefore, a knowledge and understanding of the phase behavior of these ionic liquid/CO2 systems is important. With the aim of finding ionic liquids that improve CO2 solubility and gaining more information to help us understand how to design CO2-philic ionic liquids, we present the low- and high-pressure measurements of CO2 solubility in a range of ionic liquids possessing structures likely to increase the solubility of CO2. We examined the CO2 solubility in a number of ionic liquids with systematic increases in fluorination. We also studied nonfluorinated ionic liquids that have structural features known to improve CO2 solubility in other compounds such as polymers, for example, carbonyl groups and long alkyl chains with branching or ether linkages. Results show that ionic liquids containing increased fluoroalkyl chains on either the cation or anion do improve CO2 solubility when compared to less fluorinated ionic liquids previously studied. It was also found that it was possible to obtain similar, high levels of CO2 solubility in nonfluorous ionic liquids. In agreement with our previous results, we found that the anion frequently plays a key role in determining CO2 solubility in ionic liquids.     

Why do co-solvents enhance the solubility of solutes in supercritical fluids? New evidence and opinion

The effects of two polar co-solvents, chlorodifluoromethane and acetone, on the solubility and enthalpy of a solution of 1,4-naphthoquinone in supercritical (SC) CO2 were studied. We found that the dissolution process becomes less exothermic in the presence of the co-solvents relative to that in pure CO2, although the solubility is enhanced significantly by the co-solvents. This indicates that the increase in the solubility by adding co-solvents results from the increase of the entropy of solution. On the basis of the unexpected results we propose a new mechanism for the solubility enhancement of the solute by the co-solvents in supercritical fluids (SCF); this should be applicable to cases in which the local density of the SC solvent around the solute and the co-solvent is larger, and the co-solvent associates preferentially with the solute. The results are also very important for the understanding of other fundamental questions of SCF science, such as the effect of co-solvents on the thermodynamic and kinetic properties of the reactions in SCFs.     

Solubility of stearic acid in supercritical CO_2-acetonitrile mixtures

The solubility of stearic acid in supercritical CO2 with acetonitrile (CH3CN) cosolvent was measured at 318.15 K in the pressure range from 9.5 to 16.5 MPa, and the cosolvent concentration ranges from 0. 0 to 5.5 mol% . The solubility increases with acetonitrile concentration and pressure, and it also increases with the apparent density of CO2 d1(moles of CO2 in per liter of fluid) at higher cosolvent concentrations. At lower d1, however, the solubility of the acid at lower acetonitrile concentrations is lower than that in pure CO2 provided that d1 is fixed, which is discussed qualitatively based on the clustering of the components in the system.     

Lattice Monte Carlo simulations of phase separation and micellization in supercritical CO2/surfactant systems: effect of CO2 density

Lattice Monte Carlo simulations are used to study the effect of nonionic surfactant concentration and CO2 density on the micellization and phase equilibria of supercritical CO2/surfactant systems. The interaction parameter for carbon dioxide is obtained by matching the critical temperature of the model fluid with the experimental critical temperature. Various properties such as the critical micelle concentration and the size, shape, and structure ofmicelles are calculated, and the phase diagram in the surfactant concentration-CO2 density space is constructed. On increasing the CO2 density, we find an increase in the critical micelle concentration and a decrease in the micellar size; this is consistent with existing experimental results. The variation of the micellar shape and structure with CO2 density shows that the micelles are spherical and that the extension of the micellar core increases with increasing micellar size, while the extension of the micellar corona increases with increasing CO2 density. The predicted phase diagram is in qualitative agreement with experimental phase diagrams for nonionic surfactants in carbon dioxide.     

Encapsulation and sustained release of a model drug, indomethacin, using CO(2)-based microencapsulation

A carbon dioxide (CO(2))-based microencapsulation technique was used to impregnate indomethacin, a model drug, into biodegradable polymer nanoparticles. Compressed CO(2) was emulsified into aqueous suspensions of biodegradable particles. The CO(2) plasticizes the biodegradable polymers, increasing the drug diffusion rate in the particles so that drug loading is enhanced. Four types of biodegradable polymers were investigated, including poly(d,l-lactic acid) (PLA), poly(d,l-lactic acid-co-glycolic acid) (PLGA) with two different molar ratios of LA to GA, and a poly(d,l-lactic acid-b-ethylene glycol) (PLA-PEG) block copolymer. Biodegradable nanoparticles were prepared from polymer solutions through nonsolvent-induced precipitation in the presence of surfactants. Indomethacin was incorporated into biodegradable nanoparticles with no change of the particle size and morphology. The effects of a variety of experimental variables on the drug loadings were investigated. It was found that the drug loading was the highest for PLA homopolymer and decreased in PLGA copolymers as the fraction of glycolic acid increased. Indomethacin was predicted to have higher solubility in PLA than in PLGA based on the calculated solubility parameters. The drug loading in PLA increased markedly as the temperature for impregnation was increased from 35 to 45 degrees C. Drug release from the particles is a diffusion-controlled process, and sustained release can be maintained over 10 h. A simple Fickian diffusion model was used to estimate the diffusion coefficients of indomethacin in the biodegradable polymers. The diffusion coefficients are consistent with previous studies, suggesting that the polymer properties are unchanged by supercritical fluid processing. Supercritical CO(2) is nontoxic, easily separated from the polymers, can extract residual organic solvent, and can sterilize biodegradable polymers. The CO(2)-based microencapsulation technique is promising for the production of drug delivery devices without the use of harmful solvents.     

Phase equilibria of supercritical CO_2-ethanol-stearic acid ternary system and hydrogen bonding between ethanol and stearic acid

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Hyperbranched polymers with thermoresponsive property highly sensitive to ions

The salt effects on the water solubility of thermoresponsive hyperbranched polyethylenimine and polyamidoamine possessing large amounts of isobutyramide terminal groups (HPEI-IBAm and HPAMAM-IBAm) were studied systematically. Eight anions with sodium as the counterion and ten cations with chloride as the counterion were used to measure the anion and cation effects on the cloud point temperature (T(cp)) of these dendritic polymers in water. It was found that the T(cp) of these dendritic polymers was much more sensitive to the addition of salts than that of the traditional thermoresponsive linear polymers. At low anion concentration, the electrostatic interaction between anions and the positively charged groups of these polymers was dominant, resulting in the unusual anion effect on the T(cp) of these polymers in water, including (1) T(cp) of these dendritic polymers decreasing nonlinearly with the increase of kosmotropic anion concentration; (2) the chaotropic anions showing abnormal salting-out property at low salt concentration and the stronger chaotropes having much pronounced salting-out ability; (3) anti-Hofmeister ordering at low salt concentration. At moderate to high salt concentration, the specific ranking of these anions in reducing the T(cp) of HPEI-IBAm and HPAMAM-IBAm polymers was PO(4)(3-) > CO(3)(2-) > SO(4)(2-) > S(2)O(3)(2-) > F(-) > Cl(-) > Br(-) > I(-), in accordance with the well-known Hofmeister series. At moderate to high salt concentration, the specific ranking order of inorganic cations in reducing the T(cp) of HPEI-IBAm polymer was Sr(2+) ≈ Ba(2+) > Na(+) ≈ K(+) ≈ Rb(+) > Cs(+) > NH(4)(+) ≈ Ca(2+) > Li(+) ≈ Mg(2+). This sequence was only partially similar to the typical Hofmeister cation series, whereas at low salt concentration the cation effect on T(cp) of the dendritic polymer was insignificant and no obvious specific ranking order could be found.     

Phase diagrams of blends of azide-containing polyoxetanes

The mutual solubility of polymers based on the azide-containing oxetane monomers 3,3-bis(azidomethyl)oxetane and 3-azidomethyl-3-methyloxetane is studied. The temperatures of melting, crystallization, glass transition; the upper critical solution temperature; and the compositions of coexisting phases for blends of polymers with different molecular masses are determined via differential scanning calorimetry and multiple-beam microinterferometry. On the basis of these data, the phase diagrams of blends are constructed. The melting regions and the metastable and heterogeneous states are determined. The studied systems are shown to have a complex amorphous-crystalline equilibrium and to differ in the location of boundary curves on the phase diagram, depending on the molecular mass of the components. Amorphous separation below the liquidus line in the metastable region with respect to the crystalline equilibrium is experimentally detected. The motion of the figurative point in different regions of the diagram is thoroughly considered. The specifics of structural and morphological organization of systems are examined via electron microscopy.     

四元交互体系Li+，K+/CL-，CO2-3-H2O在298 K时相平衡及物理化学性质研究

Zabuye Saline Lake, Tibet, China, is unrivalled in the world for its very high salinity, in particular, for the very high concentration of ions of lithium, potassium, and boron in the brine. It belongs to alkaline and carbonate-borate-type salt lake. As a part of the study on phase equilibrium of the 6component subsystem Li+, Na+, K+/C1-, CO2-3, B4O2-7-H2O of the brine system, a study on the reciprocal quaternary system Li+, K+/C1-, CO32-H2O at 298 K was done with isothermal dissolution equilibrium method in the present work. The phase equilibrium of the reciprocal quaternary system Li+,K+/C1, CO2-3-H2O at 298 K was studied with isothermal dissolution method in this work. The physicochemistry properties of the corresponding equilibrium solutions such as densities, viscosities, refractive index, conductivities and pH value were determined. The dried salt diagram of the system consists of four crystallization fields (KC1, Li2CO3, LiCI·H2O, K2CO3·3/2H2O) and five isothermal solubility curves.There are no double slat or solid solution found. Pitzer′s model of the electrolyte solution theory was used for parameterization from the results of solubility determination for subsystems and the prediction of solubilities for the reciprocal quaternary system was made. The solubility data of the experiment are in agreement with those calculated.