Liquid-liquid equilibrium data for ternary systems containing organic acid,hydrocarbon and water

Alessi, P., Kikic, I., Fermeglia, M. and Nonino, C., 1984. Liquid-liquid equilibrium data for ternary systems containing organic acid, hydrocarbon and water. Fluid Phase Equilibria, 18: 93–102.Experimental LLE data are presented for the acetic acid-toluene-water system at 60, 70 and 80°C and for the acetic acid-heptane-water, propionic acid-toluene-water, propionic acid-heptane-water and butanoic acid-toluene-water systems at 50, 60 and 70°C. The data are correlated by means of the NRTL and UNIQUAC models and the relevant parameters are given. The UNIFAC method is used to predict the behavior of the systems.     

The prediction of vapor-liquid equilibrium data from heat of mixing data for three non-ideal binary systems

The method of Hanks et al. was used with the heat of mixing data of McFall et al. for 1,3-butadiene + propylene, 1-butene + methyl tert.-butyl ether, and carbon disulfide + methanol to predict the vapor-liquid equilibrium behavior for these systems. The method involves curve-fitting an excess enthalpy model derived from an excess Gibbs energy model by means of the Gibbs-Helmholtz equation to the heat of mixing data, determining the adjustable parameters from this fit, and using the original excess Gibbs function equation to predict the vapor-liquid equilibrium behavior. The predicted vapor-liquid equilibrium values were compared with experimental values and good agreement was found.     

The prediction of vapor—liquid equilibrium from heat of mixing data for binary hydrocarbon—ketone mixtures

The method of Hanks et al. for predicting vapor—liquid equilibrium (VLE) from heat of mixing (h^E) data was successfully applied to binary hydrocarbon—ketone mixtures. The LEMF model for the excess free energy was found to be the most adequate to correlate experimental g^E and h^E data simultaneously for these mixtures. The predicted vapor-liquid equilibrium values were compared to experimental values and good agreement was found. The dependence of the accuracy of the VLE data predictions on the experimental uncertainties of heat of mixing data and on the set of parameters obtained by fitting these data to the algebraic equation for h^E is discussed.     

Calculation of vapour-liquid equilibrium of associated systems by an equation of state

A recently proposed equation of state of the van der Waals type is applied to calculate phase equilibria in hydrogen-bonding, non-electrolytic systems. Association is accounted for by treating alcohols, acids, etc., as mixtures of associated species formed by up to 14 monomers. The method involves essentially one weakly temperature-dependent adjustable parameter per binary system.The calculations cover vapour-liquid equilibrium both at low and elevated pressure in binary systems formed by an associating substance and a non-associating compound such as a hydrocarbon or halogenated hydrocarbon. An attempt has been made to include all experimental data available for these systems in the literature. A number of calculations for ternary systems as well as of liquid-liquid equilibria are included, and a limited number of solvated systems are also treated.Owing to its single adjustable parameter, the method may be used to test existing experimental data and to predict such data.     

Calculation of wetting angles in crude oil/water/quartz systems

A method for the determination of water-advancing wetting angles has been developed and tested. The method allows measurements in black oils, as opposed to traditional techniques which substitute transparent model oils prior to measurements. The method is based on the Laplace equation and axisymmetric drop shape analysis. The main source of error is the determination of the drop volume. Results in transparent systems are comparable to results using other techniques. Wetting angles are determined for water in two different crude oil systems, using quartz as the substrate. The quartz surfaces are water wet over large pH ranges, but it is possible to accurately identify pH intervals where the surfaces are intermediate or oil wet.     

Structural changes induced by addition of a hydrocarbon to water/amphiphile mixtures

The phase conditions in a system of water, hexadecane, sodium dodecyl sulphate, and di-ethylene glycol dodecyl ether showed theW/O microemulsions to be obtained first after destabilization of a liquid crystalline phase by addition of the hexadecane. The original lamellar liquid crystalline phase was moved towards higher surfactant/cosurfactant ratios and a new phase with inverse amphiphile cylinders in a hexagonal packing appeared.     

Adsorption at the liquid/liquid interface in mixed systems with hydrophobic extractants and modifiers 1. Study of equilibrium interfacial tension at the hydrocarbon/water interface in binary mixed systems

Equilibrium interfacial tension at the liquid/liquid interfaces for two chelating metal ion extractants, 2-hydroxy-5-nonylacetophenone oxime (HNAF) and 1-phenyldecane-1,3-dion (beta-diketone), two solvating extractants, trioctylphosphine oxide (TOPO) and tributyl phosphate (TBP), and a modifier, decanol, were obtained with a drop volume tensiometer. Moreover, four equimolar binary mixtures of extractant/extractant and extractant/modifier type were considered. The composition of the mixed adsorbed monolayer and the molecular interaction parameters beta were determined by the Rosen equation. It was found that in all the studied systems coadsorption exists; however, synergism in the reduction of interfacial tension was not observed. The obtained results indicate that in the case of three mixtures considered the composition of a mixed monolayer at the hydrocarbon/water interface was quite different from that in the bulk organic phase. Only for the TOPO/beta-diketone mixture were the compositions at the interface and in the bulk organic phase similar. The obtained results indicate that it is impossible to predict the composition of a mixed monolayer by taking into account the interfacial activity of individual components of the mixture. In some cases the compound shows lower interfacial activity (smaller efficiency and effectiveness of adsorption) and occupies a dominant position at the interface, regardless of the type of hydrocarbon used as the organic diluent.     

Application of the perturbed chain SAFT equation of state to complex polymer systems using simplified mixing rules

A simplified perturbed-chain statistical associating fluid theory (PC-SAFT) equation of state is applied to polymer systems that include a variety of non-associating (esters, cyclic hydrocarbons), polar (ketones) as well as associating (amines, alcohols) solvents. The solvent pure-component parameters that are not available in the literature are estimated by correlating vapor-pressure and liquid-density data. The performance of the simplified PC-SAFT is compared to the original PC-SAFT equation of state for polymer systems of varying complexity. It is shown that the applied simplification is not at the expense of the accuracy of equation of state, while the computational time and complexity are significantly reduced, especially for associating systems. With no binary interaction parameter, simplified PC-SAFT is successfully able to predict vapor–liquid equilibria of polymers with non-associating solvents. In the case of associating solvents, a small binary interaction parameter k_ij is usually needed for the satisfactory correlation of the experimental data.     

Combined chemical and phase equilibrium for the hydration of ethylene to ethanol calculated by means of the Peng-Robinson-Stryjek-Vera equation of state and the Wong-Sandler mixing rules

Due to the economics of the ethylene market and the subsidized production of fermentation-based ethanol in some countries, use of the ethylene hydration process to make ethanol has been steadily declining. The economics of this process might improve by combining the reaction and separation in a reactive distillation column, whose conceptual design requires a study of the combined chemical and phase equilibrium (CPE) of the reacting system. In this work, the Peng-Robinson-Stryjek-Vera equation of state was combined with the UNIQUAC activity coefficient model through the Wong-Sandler (WS) mixing rules in order to correlate the available experimental data for the vapor-liquid equilibria (VLE) of the ethylene-water, ethylene-ethanol, and ethanol-water binary systems at 200 °C. The interaction energies of the UNIQUAC model and the binary interaction coefficient of the WS mixing rules were used as the fitting parameters. From the optimum values of these parameters, both the VLE and the combined CPE of the ethylene-water-ethanol ternary system were predicted at 200 °C and various pressures. At this temperature, the catalytic activity of a H-pentasil zeolite has already been reported to exhibit a maximum for ethylene hydration, and also the experimentally measured two-phase region of the ternary system is sufficiently wide. By means of the reactive flash method, the chemical equilibrium compositions of the liquid and vapor phases were determined for several pressures, and the equilibrium conversion and the vapor fraction were calculated as functions of the ethylene to water feed mole ratio. It turns out that the vapor-liquid mixed-phase hydration of ethylene achieves equilibrium conversions much higher than those computed for a vapor-phase reaction that would hypothetically occur at the same conditions of pressure and feed mole ratio. It was found that the reactive phase diagram of the ternary system exhibits a critical point at 200 °C and 155 atm.     

Measurement of ternary polymer/solvent equilibrium data by vapor-phase infrared spectroscopy

Vapor–liquid equilibrium (VLE) data for binary toluene/PVAC, methanol/PVAC and ternary toluene/methanol/PVAC systems have been measured at 100 °C by using vapor-phase infrared spectroscopy. Binary data have been compared with literature data measured by different experimental techniques and agreement between our measurements and others was found to be good. The ternary VLE data indicate that the solubility of methanol in PVAC is not influenced by the presence of toluene, while the solubility of toluene is lowered due to presence of methanol. To predict ternary VLE data, the Entropic free volume and Kannan free volume models and the Flory-Huggins theory were used. The predictive abilities of Flory-Huggins theory and the Kannan free volume model are similar and better than that of the Entropic free volume model.     

Time–temperature superposition method for predicting the permanence of paper by extrapolating accelerated ageing data to ambient conditions

In this paper we present a time-temperature superposition method for predicting the permanence of paper by extrapolating accelerated paper ageing data to ambient conditions. The presented method includes a test for the presence of shift factors to superpose all of the raw accelerated ageing data over the temperature range studied to obtain a master curve, a numerical fit of the master curve for producing a master equation representing the kinetics of paper degradation, a critical examination of applying Arrhenius equation for explaining the relationship between the empirically determined shift factors and the accelerated ageing temperature, and a verification of the Arrhenius activation energy extrapolation assumption. Unlike the usual approach that extrapolates the Arrhenius relationship between lifetime and temperature, without corroborating evidence, to ambient temperatures, we test the Arrhenius activation energy extrapolation assumption by determining the influence of acidity on cellulose hydrolysis reactions, and have found that detection and identification of the acid-sensitive linkages in cellulose substances is an ultra-sensitive and reliable method to measure degradation of cellulose and paper in what is normally the extrapolation region (ambient temperatures). Taking the examples of natural ageing data in literature from 18 bleached kraft dry-lap pulps for 22 years under ambient conditions and three handsheet samples for 22 years under controlled conditions, comparison of the predictions with natural ageing results has been addressed.     

Application of refractive index mixing rules in binary systems of hexadecane and heptadecane with n -alkanols at different temperatures

Density and refractive index have been experimentally determined for binary liquid mixtures of hexadecane and heptadecane with 1-butanol, 1-pentanol, 1-hexanol and 1-heptanol at 298.15, 308.15 and 318.15 K. A comparative study of Lorentz—Lorenz (L-L), Weiner (W) and Heller (H), and Gladstone-Dale (G-D) relations for predicting the refractive index of a liquid has been carried out to test their validity for the eight binaries over the entire mole fraction range of hexadecane and heptadecane at the three temperatures. Comparison of various mixing rules has been expressed in terms of average percentage deviation. The performance of the Lorentz-Lorenz and Heller relations is relatively better than that of the Weiner and Gladstone-Dale relations.     

Studies of surfactant/water systems near the critical micellar concentration using thermal lens spectroscopy

A novel application of photothermal spectroscopy to the study of surfactant-water systems near the critical micellar concentration is reported. The thermal lens signal was induced by a slightly soluble dye and was measured with a dual-beam thermal lens spectrometer.For the two surfactants considered: nonyl phenol and Triton X-100, sharp variations of the thermal lens signal were observed at the critical micellar concentration (CMC), namely an increase for nonyl phenol and a decrease for triton X-100. These effects are arguably related to micelle formation.Our work serves as an initial assessment of the potential of the technique for the study of disperse systems of a higher complexity or dark systems where conventional techniques are impossible to apply.     

丙烯腈、己二腈和丙腈与水的二元体系液-液相平衡数据的测定和关联(英文)

采用平衡法测定了丙烯腈+水、己二腈+水、丙腈+水三个二元体系在不同温度(303.15、313.15、323.15、333.15K)下的液-液相平衡数据;并采用NRTL(α=0.2,α=0.3)模型和UNIQUAC模型对液-液平衡数据进行了关联.结果显示,NRTL和UNIQUAC模型对三个二元体系在不同温度下的互溶度关联的目标函数值均小于1×10-17,实验值与计算值吻合较好,绝对偏差小于0.009,关联精度较高.该研究结果可为丙烯腈、丙腈和水三元平衡溶解度数据的模拟和预测提供可靠的基础数据,并对电解二聚法生产己二腈中电解液的分离提纯工艺具有一定的指导意义.     

吹扫捕集-GC／MS测定水中的挥发性卤代烃和苯系物

以吹扫捕集系统富集,PONA毛细管柱分离,GC/MS法测定水中的挥发性卤代烃和苯系物。对色谱柱的选择,吹扫流量、时间以及解析时间等影响因素进行了优化选择。方法实现了对水中苯、乙苯、对、间二甲苯、邻二甲苯、甲苯、苯乙烯、三氯化碳、四氯化碳、三氯乙烯、四氯乙烯等挥发性卤代烃和苯系物的同时富集和测定,成功分离了苯乙烯和邻二甲苯。方法平均回收率为90%~105%,检出限为0.017~0.194μg/L,精密度(RSD)为1.8%~4.3%(n=6)。方法可用于水中挥发性卤代烃和苯系物的同时测定。     

Comparison of T-piece and concentric mixing systems for continuous flow synthesis of anatase nanoparticles in supercritical isopropanol/water

T-piece and concentric counter-flow mixing systems are compared in continuous flow supercritical solvothermal synthesis of TiO₂ at identical system parameters. The phase pure anatase nanoparticle products were characterized with powder X-ray diffraction (PXRD), transmission electron microscopy (TEM) and small angle X-ray scattering (SAXS), and the particle size, size distribution and absolute crystallinity mapped as a function of temperature, precursor concentration, flow rate and pressure for the two different continuous flow reactors. The particles synthesized with the T-piece geometry are smaller with a narrower size distribution, possibly indicating a more effective mixing, than particles synthesized at the same conditions with concentric counter-flow geometry. In general, an increased synthesis temperature leads to an increase in absolute crystallinity. For the particles synthesized with the concentric reactor geometry crossing of the critical point of the solvent causes a decrease in the particle size and size distribution, and conditions just above the critical temperature are demonstrated to be optimal for continuous solvothermal synthesis of anatase.     

Solubilisation of triolein by microemulsions containing C12E4/hexadecane/water: equilibrium and dynamics

Increasing triolein content of oil-in-water microemulsions in the pure C(12)E(4)/water/n-hexadecane/triolein system while maintaining a fixed surfactant concentration and volume fraction of drops raises the temperature of the solubilisation boundary, where excess oil separates, but has only a slight effect on the (higher) cloud point temperature, where excess water appears. Thus, the temperature range of the single-phase microemulsion shrinks and ultimately disappears. When such microemulsions are in equilibrium with excess oil, the hexadecane/triolein ratio is greater in the microemulsion, probably because the larger triolein molecules are unable to penetrate the hydrocarbon chain region of the surfactant films of the microemulsion droplets. Indeed, monolayer studies and calculations based on microemulsion and excess oil compositions indicate that the films have minimal triolein and similar ratios of hexadecane to surfactant. Triolein drops brought into contact with hexadecane-in-water microemulsions first swell as they incorporate hexadecane, then shrink owing to solubilisation. Interfacial tension decreases during this process until it becomes almost constant near 0.01 mN m(-1), suggesting that the drops in the final stages of solubilisation have high hexadecane contents. A microemulsion containing 10 wt% C(12)E(4) and 15 wt% hexadecane was able to remove over 50% of triolein from polyester fabric at 25 degrees C, more than twice that removed by an oil-free solution with the same surfactant concentration in similar experiments.     

Calculation of self-absorption coefficients of calcium resonance lines in the case of a CaCl2–water plasma

The resonance escape factors for the lines emitted by a neutral calcium atom Ca I at 4226.73 Å and of ionic calcium Ca II at 3933.66 Å and at 3968.47 Å are calculated assuming a Voigt profile and in the case of CaCl₂–water plasma. The dependence of the escape factor on the optical thickness ?₀ from the line center which itself depends on the two main spectral line shape broadening mechanisms (pressure and Doppler effects) are considered. The variation of the resonance escape factors with the temperature, the CaCl₂ molar proportion and the size of the plasma are also investigated. This calculation is useful for the application of Laser-Induced Breakdown Spectroscopy in the quantitative analysis of elemental composition. Its application allows us to reduce the non-linearities in the relation between resonance lines intensities of calcium in our case and its concentration.