Experimental measurement and thermodynamic modeling of binary and ternary solid-liquid phase equilibrium for the systems formed by L-arabinose,D-xylose and water

Solid-liquid phase equilibrium data for binary (L-arabinose-water) and (D-xylose-water) systems at temperatures from (269.85-298.05) K and ternary (L-arabinose-D-xylose-water) system at temperatures of 273.85 K,278.85 K and 284.45 K were measured at atmospheric pressure.The ternary phase diagrams of the systems were constructed on the base of the measured solubility.Two pure solid phases were formed at given temperatures,including pure L-arabinose and pure D-xylose,which were confirmed and determined by the method of Schreinemakers' wet residue.At the same temperature,the crystallization region of L-arabinose was larger than D-xylose's.The acquired solubility data were then correlated using the NRTL model,Wilson model and Xu model.The calculated solubility with the three models agreed well with the experimental values.     

1,2-环氧环己烷和1,2-二氯乙烷二元体系汽液平衡数据的测定与关联(英文)

Vapor-liquid equilibrium data (T, x, y) of binary system 1,2-epoxycyclohexane + 1,2-dichloroethane were determined experimentally by using a modified ROSE-Williams equilibrium vaporization system at 101.33 kPa. The results show that this binary system does not have azeotropic point. The vapor-liquid equilibrium data are in thermodynamic consistency. The binary interaction parameters in the Wilson equation are presented with the correlation of vapor-liquid equilibrium data. The measurements of liquid phase composition and bubble point temperature are well represented by the Wilson equation. Values of vapor molecular fractions and activity coefficients from the Wilson equation are presented. This work provides important engineering data for the separation of 1,2-dichloroethane and 1,2-epoxycyclohexane .     

Liquid-Liquid Equilibria of the Water-Ethanol-Dimethyl Succinate Ternary System

Liquid-liquid equilibrium (LLE) data for the ternary system water-ethanol-dimethyl succinate have been determined experimentally at temperatures ranging from 298.15 to 318.15K at 5K intervals. Complete phase diagrams were obtained by determining solubility and the tie-line data. Tie-line compositions were correlated by Othmer-Tobias method. The universal quasichemical functional group activity coefficient (UNIFAC) and modified UNIFAC methods were used to predict the phase equilibrium in the system using the interaction parameters determined from experimental data between groups CH3, CH2, OH, CH3COO and H2O. It is found that UNIFAC and modified UNIFAC group interaction parameters used for LLE could not provide a good prediction. Distribution coefficients and separation factors were evaluated for the immiscibility region.     

水,乙醇和丁二酸二甲酯三元体系的液体平衡

Liquid-liquid equilibrium (LLE) data for the ternary system water-ethanol-dimethyl succinate have been determined experimentally at temperatures ranging from 298.15 to 318.15 K at 5 K intervals. Complete phase diagrams were obtained by determining solubility and the tie-line data. Tie-line compositions were correlated by Othmer-Tobias method. The universal quasichemical functional group activity coefficient (UNIFAC) and modifiedUNIFAC methods were used to predict the phase equilibrium in the system using the interaction parameters determined from experimental data between groups CH3, CH2, OH, CH3COO and H20. It is found that UNIFAC and modified UNIFAC group interaction parameters used for LLE could not provide a good prediction. Distribution coefficients and separation f~ctors were evaluated for the immiscibility region.     

盐对水+丙酸+环乙醇三相体系在298.2，303.2和308.2 K下液液相平衡的影响

Effects of salt and temperature on the liquid phase equilibrium of the (water + propionic acid + cyclohexanol) system were investigated. The liquid-liquid equilibrium data in the presence of KCl for various salt ionic strength of 0.5, 1.0, 1.5, 2.0, and 2.5 mol•dm3 and in absence of the salt at T (298.2, 303.2, and 308.2) K were determined. The experimental results were correlated based on the Othmer-Tobias equation and Pitzer ion-interaction model. Thermodynamic properties such as distribution coefficients and activity coefficients of propionic acid in water + cyclohexanol were determined. In addition, the separation factor, S, of the chosen solvent was obtained for the investigated system.     

Thermodynamic modeling and phase diagram prediction of salt lake brine systems Ⅱ. Aqueous Li~+-Na~+-K~+-SO_4~(2-) and its subsystems

It is still a challenging task to accurately and temperature-continuously express the thermodynamic properties and phase equilibrium behaviors of the salt-lake brine with multi-component,multitemperature and high concentration.The essential subsystem of sulfate type brine,aqueous Li~+-Na~+-K~'-SO_4~(2-) and its subsystems across a temperature range from 250 K to 643 K are investigated with the improved comprehensive thermodynamic model.Liquid parameters(Δg_(IJ),Δh_(IJ),and ΔC_(p,IJ)) associated with the contributions of Gibbs energy,enthalpy,and heat capacity to the binary interaction parameters,i.e.the temperature coefficients of eNRTL parameters formulated with a Gibbs Helmholtz expression,are determined via multi-objective optimization method.The solid constants Δ_fG_k°~((298.15)) and Δ_fH_k°~((298.15)) of11 solid species occurred in the quaternary system are rebuilt from multi-temperature solubilities.The modeling results show the accurate representation of(1) solution properties and binary phase diagram at temperature ranges from eutectic points to 643 K;(2) isothermal phase diagrams for Li_2SO_4-Na_2SO_4-H_2O,Li_2SO_4-K_2SO_4-H_2O and Na_2SO_4-K_2SO_4-H_2O ternary systems.The predicted results of complete structure and polythermal phase diagram of ternary systems and the isothermal phase diagrams of quaternary system excellently match with the experimental data.     

ISOBARIC VAPOR-LIQUID EQUILIBRIUM OF ISOBUTENE-ISOPRENE-CHLOROMETHANE SYSTEM AT 1.03 MPa

An isobaric vapor-liquid equilibrium apparatus at elevated pressure has been developed for measurement. The isobaric vapor-liquid equilibrium data of three binary systems (isobutene-isoprene, isobutene-chloromethane and isoprene-chloromethane) and a ternary system (isobutene-isoprene-chloromethane) have been determined at 1.03 MPa and correlated satisfactorily with the Martin-Hou equation of state (81).     

亚临界和超临界状态下甲苯-多环芳香烃体系的气液相平衡

The phase behaviors of toluene/polycyclic aromatic hydrocarbon mixture systems were investigated with a continuous-flow type apparatus at 573.2,598.2.623.2 and 648.2K,while the pressure changed from 1 tp 5 MPa,The pseudo-binary phase behaviors were predicted with the Peng-Robinson equation of state with interaction parameters between toluene and pseudo-components considered.The phase diagrams of the system have been classified following the category of phase boundary diagram models.The extraction selectivity and efficiency of toluene as a solvent was discussed by comparing with that of hexane .The prediction model for selectivity was also suggested.     

Phase Partition of Acrylonitrile (AN) in Vinylidene Chloride (VDC)/Water System and Its Effect on VDC-AN Copolymer Composition

phase partition of acrylvnitrile in the vlnylidene chloride/water system at different temperature and under pressure was studied, A calculation method for average VDC-AN copolymer compeeition with AN phmm partition considered was proposed. The conversion results are in good agreement with the experimental data nearly the entire conversion rauge. VDC-AN copolymer with narrower composltion distribution can be prepared in the suspension process and interpreted with dynamic equilibrium of AN between the oil and water phases continuously.     

Isobaric vapor–liquid equilibrium for binary system of aniline+methyl-N-phenyl carbamate

In this study,the quasi-static ebulliometric method was used to measure both of the vapor pressures of methyl N-phenyl carbamate(MPC),and the isobaric vapor–liquid equilibrium(VLE) data of the aniline and MPC binary system.The measured vapor pressure data of MPC,at different temperature ranging from 369.60 to 389.54 K,fitted well with the Antoine equation.The VLE data for the aniline and MPC system at(2.00,4.00,6.00,7.00 and 8.00) k Pa were correlated by both of nonrandom two-liquid(NRTL) and Wilson models.The parameters of the two models were obtained by regressing the experimental data,with the absolute temperature deviations of 0.54 K and 0.53 K,respectively.The relative volatility of the binary system calculated was all far more than 1,which gives the conclusion that the high purity MPC can be separated from aniline and MPC binary system by rectification or distillation technology.     

High‐pressure phase equilibria for a styrene/CO2/polystyrene ternary system

To reveal the possibility of supercritical (SC)‐CO₂‐assisted devolatilization of polystyrene, the equilibrium composition data for the CO₂ phase in a styrene/CO₂/polystyrene ternary system is determined by a semistatic experimental technique. The parameters in the lattice–fluid equation of state of Sanchez and Lacombe are determined for the investigated system. The distribution coefficients of styrene between the polymer and the supercritical fluid phases are investigated experimentally at 318 and 328 K over the pressure range of 12–20 MPa. The binary interaction parameter between styrene and CO₂ is obtained by regression of the vapor–liquid equilibrium data. The interaction parameter between CO₂ and polystyrene is calculated by using the sorption data from the literature, and the interaction parameter between styrene and polystyrene is optimized by using the measured data of this study. The investigation of the distribution coefficients indicates that styrene can be removed from polystyrene by SC‐CO₂ at near room temperature and moderately high pressures. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 1938–1944, 2002     

Ternary phase equilibria of the iso-propanol+water+carbon dioxide system at high pressure

Ternary phase diagrams are presented for the system: iso-propanol(IPA)+water+carbon dioxide at temperatures from 15 to 70 °C and pressures from 7 to 17 MPa. The distribution coefficients of IPA between the dense phase carbon dioxide and water changed dramatically with temperature and pressure. In the vicinity of the critical point, distribution coefficients was low, yet at liquid-like densities carbon dioxide had a high affinity for IPA. Selectivity reversal was observed at differing pressures. High selectivity of CO₂ for IPA was achieved in the near-critical liquid and in supercritical carbon dioxide at high pressure.     

Distribution of solutes between polymer and supercritical fluid by inverse supercritical fluid chromatography

Two methods of inverse supercritical fluid chromatography (ISFC), frontal analysis supercritical fluid chromatography (SFC) and elution SFC, have been compared for the determination of distribution coefficients of solutes between a polymer and a supercritical CO₂. The logarithm of the distribution coefficient showed monotonic decrease with the density of the supercritical fluid (SF). The abnormal-maximum behavior of solute sorption in the polymer phase was explained by the fluid and solute properties, ϕ₂P/P ₂ ^sat . Interesting open-elliptic shapes of sorption and volume-fraction curves were obtained and explained with the fugacity coefficient. Correction to the capacity factor was employed to eliminate the retention due to the adsorption on the surface of the silica support. A model based on the Flory equation and the Peng-Robinson equation of state (EOS) successfully predicted the phase behavior of the ternary solutesupercritical fluid-polymer systems using only interaction parameters obtained from the binary systems. The solute distribution coefficient at infinite dilution was used to calculate the phase equilibrium at finite concentration using a ternary-phase diagram.     

A theoretical and experimental heat of mixing study for polymer‐polymer mixtures

Heat of mixing is introduced as a guide for phase stability predictions of polymer mixtures, and an appropriate equation is presented for it. The form of this equation is a combined function of temperature and mixture composition. The capability of the presented equation has been treated qualitatively and it has been shown that all types of exothermic, endothermic, and s‐shaped or sigmoidal heat of mixing curves can be produced. Utilizing the low molecular weight analogue calorimetry method, heat of mixing was measured at two temperatures, 27°C and 37°C for three polymer mixtures—poly(styrene)/poly(vinylchloride) (PS/PVC), poly(styrene)/ poly(methylmethacrylate) (PS/PMMA), and poly(styrene)/poly(vinylacetate) (PS/ PVAc) at an entire composition range. It has been shown that excellent agreement between the results of the calculations and the experimental heat of mixing data was achieved. Using the results of analogue calorimetric measurements for phase stability studies of polymer mixtures, it was found that often, acceptable predictions can be made by this method, but they are not always completely true.     

二甲醚-甲醇-水三元体系汽液平衡的测定与计算

利用自吸式搅拌静态平衡釜,测定了333.15、353.15、373.15、393.15 K下二甲醚-甲醇-水三元体系的等温汽液平衡数据.二甲醚在气液相中的含量随压力的提高而增大,随温度的升高而减小.采用状态方程-活度因子法,由PR方程计算气相各组分的逸度因子, NRTL方程计算液相活度因子,进行了二甲醚-甲醇-水三元体系汽液平衡数据的热力学计算.模型计算值与实验值吻合良好.     

Vapor–liquid equilibria for benzene/polybutadiene and cyclohexane/polybutadiene systems at 333, 355, and 373 K using gas chromatography

A perturbation chromatography apparatus has been designed and constructed for determining the vapor–liquid equilibrium between a two-component (solvent/helium) vapor phase and a two-component (polymer/solvent) liquid phase. The apparatus performed very well, giving reproducible and reliable results that agree with independent, previously reported studies. All tests of the equipment indicated that it was successful in meeting the conditions of low column pressure drop, small perturbations, and slow flow rate that are required for perturbation chromatography. Binary polymer/solvent data were obtained for polybutadiene (PBD)/benzene or polybutadiene/cyclohexane systems at solvent partial pressures to 40 kPa and for n-hexane at infinite dilution, all at the three temperatures of 333.15, 355.00, and 373.15 K. The experimental data for each system can be represented within experimental error by the Flory–Huggins polymer solution theory using a single binary interaction parameter that is independent of temperature and concentration.     

Modelling of polymerization kinetics and molar mass development in the nitroxide-mediated polymerization (NMP) of styrene in supercritical carbon dioxide using the PC-SAFT equation of state

A mathematical model for polymerization kinetics and molar mass development in the nitroxide-mediated polymerization (NMP) of vinyl monomers in supercritical carbon dioxide (scCO₂) has been developed. The method of moments is used for molar mass development. The perturbed-chain statistical associating fluid theory (PC-SAFT) equation of state is used to estimate the number of stable phases present at equilibrium in the reaction mixture, critical number average chain length at which polymer particles are formed, and monomer concentration in each phase. Pure and binary PC-SAFT interaction parameters are estimated from liquid–liquid equilibrium (LLE) and liquid–vapour equilibrium (LVE) experimental data at 60 to 129°C. The effect of pressure on monomer conversion and molar mass development in the polymerization of styrene (Sty) using benzoyl peroxide (BPO) and 2,2,6,6-Tetramethylpiperidinyl-1-oxyl (TEMPO) at 120°C and 300–500 bar is studied. It was observed that increasing pressure increases polymerization rate without significantly affecting molar mass development.     

PC-SAFT Equation: A Predictive Tool to Determine Experimental Conditions for Polymer Blend Demixing

Abstract

The perturbed-chain statistical associating fluid theory equation of state (PC-SAFT) was applied to predict the phase behavior of polymer solutions in order to determine the pressure – temperature region for the high molecular weight polymer blend separation by using n-alkanes at high pressure and high temperature. The polymer blends selected were physical blends of polyethylene (PE)/polystyrene (PS), and polypropylene (PP)/PS. The miscibility and immiscibility region of each polymer in different alkanes (n-pentane, n-hexane, and n-heptane) was studied and from this analysis, the experimental conditions of the polymer blend demixing were predetermined. The results obtained were validated with experimental data indicating that the PC-SAFT equation is a good tool to predict experimental conditions for the processing windows of polymer blend separation.     

The behavior of bubbles in Bueche model fluids

The nonlinear oscillation of a spherical gas bubble in polymer solutions was theoretically analyzed. Using the rheological equation of Bueche model fluid, the equation of motion and the pressure equation for a bubble are derived. According to the numerical calculations, the effects of rheological properties and initial radius of the bubble on the bubble radius-time history, pressure at the bubble wall, critical and equilibrium radii of the bubble, as well as pressure distribution in liquid are discussed.