PVDF/PS共混超滤膜的研究

研究了ＰＶＤＦ与ＰＳ的不同溶混性。分析了聚合物溶混程度变化及工艺条件改变对膜形态结构及使用性能的影响。实验结果表明，ＰＶＤＦ和ＰＳ属部分溶混体系，由这种溶混体系制成的超滤膜水通量有较大幅度提高。

Solubilities of Isophthalic Acid in Acetic Acid ＋ Water Solvent Mixtures

The solubilities of isophthalic acid （1） in binary acetic acid （2） ＋ water （3） solvent mixtures were determined in a pressurized vessel. The temperature range was from 373.2 to 473.2K and the range of the mole fraction of acetic acid in the solvent mixtures was from x2 = 0 to 1. A new method to measure the solubility was developed, which solved the problem of sampling at high temperature. The experimental results indicated that within the temperature range studied, the solubilities of isophthalic acid in all mixtures showed an increasing trend with increasing tem- perature. The expe^mental solubilities were co .rrelated by the Buchowski equation, and the calculate results showed good agreement with the experimental solubilities. Furthermore, the mixed solvent systems were found to exhibit a maximum solubility effect on the solubility, which may be attributed to the intermolecular association between the solute and the solvent mixture： The maximum solubility effect was well modeled by the modified Wilson equation.

Dissolution behaviors of Ta_2O_5,Nb_2O_5 and their mixture in KOH and H_2O system

The dissolution behaviors of Ta2O5,Nb2O5 and their mixture in KOH and H2O system were investigated.A L9(34) orthogonal design was used to study the effects of reaction temperature,mass ratio of KOH to Ta2O5,and reaction time on the dissolution rate of tantalum.It was found that the effect of reaction temperature on the dissolution rate of tantalum was much greater than that of the other factors.The results of factorial experiments showed that Ta2O5 was mainly transformed into insoluble potassium tantalate at low temperature(350 ℃) and transformed into soluble potassium tantalate at high temperature(450 ℃).The insoluble potassium tantalate was analyzed by XRD,which was proved to be KTaO3.Differently,almost all Nb2O5 was transformed into soluble potassium niobate at 350-450℃.As for the mixture of Ta2O5 and Nb2O5,the dissolution rate of tantalum increased and the dissolution rate of niobium decreased as an interaction existed between niobium and tantalum.And increasing the mole ratio of Nb2O5 to Ta2O5 in the mixture was beneficial to the dissolution of both Ta2O5 and Nb2O5.In addition,the mechanism of the interaction between niobium and tantalum was also investigated through phase and chemical analysis.

Phase Equilibrium Calculations in Mixtures Containing Caprolactam with a UNIFAC Model

An extended liquid-liquid equilibrium(LLE) UNIFAC model is proposed to describe phase equilibria of mixtures containing caprolactam.In this model,caprolactam is introduced as a new group.New group interaction parameters are calibrated from 156 sets of liquid-liquid equilibrium data.The present model gives satisfactory correlation and prediction in liquid-liquid equilibrium,including quaternary systems containing the mixed solvent of an alcohol and an alkane.The model can be applied to predict caprolactam solubility in water and benzene accurately.Freezing point and vapor-liquid equilibrium of binary systems containing caprolactam are also predicted with the extended LLE UNIFAC model.Satisfactory prediction results are obtained.

Transport of Indium, Gallium and Thallium Metal Ions Through Chromatographic Fiber Supported Solid Membrane in Acetylacetone Containing Mixed Solvents

The transport of metal ions of indium, gallium and thallium from source solution to receiving phase through the chromatographic fiber supported solid membrane in the acetylacetone （HAA） containing mixed solvent system has been explored. The fibers supported solid membranes were prepared with chemical synthesis from cellulose fibers and citric acid with the carboxylic acid ion exchange groups introduced. The experimental variables, such as concentration of metal ions （10^-2 to 10^-4 mol.L^-1） in the source solution, mixed solvent composition [for exampl, e, acetylacetone, （2,4-pentanedione）, （HAA） 20% （by volume）, 1,4-dioxane 10% to 60% and HC1 0.25 to 2 mol.L^-1] in the receiving phase and stirring speed （50-130 r.min ） of the bulk source and receiving phase, were explored. The efficiency of mixed solvents for the transport of metal ions from the source to receiving phase through the fiber supported solid membrane was evaluated. The combined ion exchange solvent extraction （CIESE） was observed effective for the selective transport of thallium, indium and gallium metal ions through fiber supported solid membrane in mixed solvents. The oxonium salt formation in the receiving phase enhances thallium, indium and gallium metal ion transport through solid membrane phase. The selective transport of thallium metal ions from source phase was observed from indium and gallium metal ions in the presence of hydrochloric acid in organic solvents in receiving phase. The separation of thallium metal ions from the binary mixtures of Be（II）, Ti（IV）, AI（III） Ca（II）, Mg（II）, K （I）, La（III） and Y（III） was carried out in the mixed solvent system using cellulose fiber supported solid membrane.

Study on Critical Properties for CO_2+Cosolvent Binary System and Ternary System

The performance of supercritical fluid (SCF) as a solvent can be greatly affected by addition of anentrainer to the system. In this study, a constant volume visual method is used to measure the critical point ofCO2+n-butyraldehyde, CO2+ i-butyraldehyde and CO2+alcohol binary systems and CO2+entrainer+trisodiumsalt of tri-(m-sulfonphenyl)phosphine (TPPTS) ternary systems, which provides us good theoretical basis for super-critical extraction and chemical reaction. The relationship between critical point and concentration of the entrainerare discussed. The phase behavior of binary system and that of ternary system are compared. The relationshipbetween the concentration of TPPTS and critical point of binary systems are also discussed.