Liquid-Liquid Equilibrium for 1-Butanol-Water-KF and 1-Butanol-Water-K_2CO_3 Systems

KF or K2CO3 was added into the 1-butanol-water system and two phases were formed： water-rich phase （water phase） and 1-butanol-rich phase （1-butanol phase）. The liquid liquid equilibrium （LLE） data for 1-butanol-water-KF and 1-butanol-water-K2CO3 systems were measured at 25℃ and showed that 1-butanol phase contained negligible salt and water phase contained negligible 1-butanol when the concentrations of KF and K2CO3 in the water phase were equal to or higher than 27.11% and 31.68% , respectively. Thus water could be separated efficiently from 1-butanol-water by adding KF or K2CO3 into the system. A theoretical calculation of LLE data was calculated by using the Pitzer theory to get water activity in the water phase, and by the models, such as the Wilson, NRTL or the UNIQUAC for the 1-butanol phase. For 1-hutanol-water-KF system, the experimental data were found in good agreement with the calculated results by using Pitzer theory and Wilson equa tion, while for 1-butanol-water-K2CO3 system, the experimental data were found in good agreement with the calculated results by using Pitzer theory and UNIQUAC eauation.

Salt Effect on the Liquid-Liquid Equilibrium of （Water ＋ Propionic Acid ＋ Cyclohexanol） System at T=（298.2,303.2,and 308.2） K

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·dm3 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.

The extraction of aromatics using N-methylpyrrolidone: Liquid-liquidequilibrium determination and mechanism exploration

LLE data of cyclooctane/3-methylpentane + benzene/toluene + N-methylpyrrolidone (NMP) at 298.15 Kand 313.15 K under a pressure of 101.3 kPa were measured in this work. The Othmer-Tobias and Handequations were adopted to validate the reliability of LLE data, where the correlation coefficients (R2) wereclose to unity, indicating the high reliability of the experimental data. The experimental data were analyzed using the distribution coefficient (D) and separation factor (S), and the effect of NMP extracting benzene and toluene from aromatics was explored. Meanwhile, the reason for the different extractionefficiencies of benzene and toluene using NMP was analyzed by quantum chemical calculations. TheNRTL and UNIQUAC thermodynamic models were used to correlate the liquid–liquid equilibrium data,and the relevant binary interaction parameters were obtained. The calculated root mean square deviation(RMSD) were all less than 0.0063, indicating that the obtained binary interaction parameters can be usedto simulate and calculate the extraction of aromatics using NMP.

Ternary Liquid-Liquid Equilibrium for Systems of Fatty Acid Methyl Ester(Methyl Palmitate/Methyl Stearate)+Ethanol+Glycerol at Atmospheric Pressure

Liquid-liquid equilibrium data of two ternary systems methyl palmitate+ethanol+glycerol and methyl stearate+ethanol+glycerol at(318.2 and 333.2)K and atmospheric pressure were measured. The values of distribution coefficient and selectivity were calculated, which indicates that glycerol can be separated from fatty acid ester by using ethanol as an extraction solvent. The consistency of the isothermal tie-line data were checked by the Othmer-Tobias equation. The correlation coefficients R2 are higher than 0.993,9 for all the fitted curves. The NRTL activity coefficient model was applied to the correlation of the measured tie-line data. The root mean square deviation(RMSD)values are less than 0.007 for all the systems, which shows a good predictive capability of this model for such systems.

Measurement and Correlation of Liquid-liquid Equilibria for 1-Hexene-n-Hexane-3-Methysulfolane

Utilizing solvent extraction to separate alkanes and olefins from catalytic light gasoline is an effective method for maximizing the utility of gasoline fractions.This study presents the determination of liquid-liquid equilibrium data for the ternary system of 1-hexene-n-hexane-3-methylsulfolane at 30℃,40℃,and 50℃under atmospheric pressure.The obtained data facilitated the construction of a ternary phase diagram for the system.The results showed that the extraction selectivity of 1-hexene/n-hexane exceeded 1.5 when using 3-methylsulfolane as the extraction solvent.Furthermore,the thermodynamic consistency of the experimental data was examined using Hand’s equation and the Othmer-Tobias method.The correlation coefficient,R^(2)≥0.9578,indicated the acceptable reliability of the phase equilibrium data.Subsequently,the NRTL(non-random two liquid)model was used to correlate the liquid-liquid phase equilibrium data and derive the binary interaction parameter.Notably,the results demonstrated that the root mean square deviation of the NRTL model correlation values from the experimental values did not exceed 2.5%.

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.

Measurement and correlation of phase equilibrium data of the mixtures consisting of water, resorcinol, mesityl oxide at different temperatures

Liquid–liquid equilibrium(LLE) data were measured for the ternary system of water + resorcinol + mesityl oxide under atmospheric pressure at temperatures of(298.2, 323.2, 333.2, 343.2 and 353.2) K. The reliability of the experimental data was verified by the Hand and Bachman equations. The distribution coefficient and selectivity were calculated from the experimental LLE data, which showed high efficiency of mesityl oxide extracting resorcinol from the aqueous solution. The NRTL and UNIQUAC models were employed to fit the measured experimental LLE data and yield corresponding binary interaction parameters.

Salt effect on the liquid–liquid equilibrium of the ternary (water + phenol + methyl isobutyl ketone) system: Experimental data and correlation

The effects of NaCl, KCl and Na_2SO_4 on the liquid–liquid equilibrium(LLE) data for the ternary system, water+ phenol + methyl isobutyl ketone, were determined at 0.101 MPa and 333.15 K and 343.15 K.The nonrandom two-liquid(NRTL) model was used to correlate the experimental data and to yield corresponding binary interaction parameters for these salt containing systems.The Hand and Othmer–Tobias equations were used to confirm the dependability of the determined LLE data in this work.Distribution coefficient and selectivity were used to evaluate the extraction performance of methyl isobutyl ketone with the existence of salt.The magnitude of salt effect on the water + phenol + methyl isobutyl ketone(MIBK) system is in the following order: Na_2SO_4>NaCl>KCl.

Efficient separation of phenols from coal tar with aqueous solution of amines by liquid-liquid extraction

In this paper,a method of extracting phenols from coal tar by amines aqueous solution was proposed.The effects of various amines on the extraction properties of phenols in coal tar were researched from the views of molecular structure.The parameters such as molar ratio,concentration,extraction time and temperature for the extraction of coal tar by the monoethanolamine and ethylenediamine aqueous solution were examined.The results show that the organic amine with more amino groups,hydroxyl structure and strong electronegativity exhibited better extraction performance.Under the optimal conditions,the extraction yields of phenols in coal tar by the monoethanolamine or ethylenediamine aqueous solution are above 80%,and the recovery yields of amines reach 99%.Furthermore,the probable geometries of complexes formed by the combination of phenols and organic amines were calculated by density function theory.In addition,several thermodynamic models were evaluated through comparing the relative deviation of simulation results by ASPEN PLUS to the experimental ones,which provide feasibility thermodynamic models for the simulation of extraction process.The present work affords a mild,efficient and green approach for the extraction of phenols from coal tar by an aqueous solution of amines in industry application.

Modeling of Liquid-Liquid Extraction Process for Glycerol Purification from Biodiesel Production

This paper shows some generalities about the glycerin byproduct obtained from biodiesel production process, presents an analysis of the ternary equilibrium between methanol, water and glycerol, and shows the influence that temperature has on the balance. This phase diagram illustrates ternary equilibrium at 10, 20 and 50 ℃, keeping the pressure constant at 1 atm （atmosphere） to standardize the analysis. The purpose of it is to establish the best temperature for the purification of glycerol by liquid-liquid extraction method under the ＂extraction in several stages cross flow＂ taking an initial mixture of glycerol with composition 15 wt.% water, 25 wt.% methanol and 60 wt.% glycerol. Water was used as liquid-liquid extraction solvent in order to remove as much methanol as possible from the initial solution due to the existence of a zone of insolubility between the glycerol and water in the ternary equilibrium. By this reason, two solutions are obtained, one consisting of water and methanol containing a trace of glycerin and the other consisting of water, glycerine and traces of methanol, which contain only 4.62% of the total methanol which enter in the process of liquid-liquid extraction, with 60.62% of the total glycerol, which is sent to a fractional distillation process to purify glycerin up to 98% by weight.

Density,refractive index and liquid–liquid equilibrium data of polyethylene glycol 3000 + potassium formate + water at different pH values

New liquid-liquid equilibrium data for polyethylene glycol （PEG） 3000 ＋ CHO2K ＋ H20 systems were measured at 298.15 K and pH values of 7.95, 8.40 and 9.98. It was found that an increase in pH caused the binodal curve to be displaced downward and the two-phase region to expand. Accordingly, the binodal curve was adjusted to the Pirdashti equation and the tie-line compositions were correlated using the Othmer-Tobias, Bancroft and Hand equations. The study measured the refractive index and densities of several homogeneous binary and ternary solutions. The solutions were used for calibration within a range of 0% to 30% of the mass of the PEG and potassium formate. The density and refractive index data show a linear variation with the mass fraction of the polymer and the salt. The effect of pH on the binodal, tie-line lengths （TLL） and slope of the tie-line （STL） in the systems was exam- ined. It was found that an increase in pH increased the TLL and decreased the STL It was observed that the density of the aqueous two-phase system was influenced by the TLL The difference in density between phases （△p） increased as the TLL and pH increased. It was found that the TLL and Ap showed a linear relationship. The effective excluded volume （EEV） of the PEG was obtained and it was found that EEV also increased as the pH increased.

水-异丙醚-苯酚和水-异丁醇-苯酚体系的液液平衡研究

水-异丙醚-苯酚体系的研究在工业上和环境保护上具有重要意义,但至今未见到液液平衡(LLE)数据的报导。今报导了这一系统在两个工作温度的LLE数据。为了寻找萃取剂异丙醚的替代物,我们同时进行了水-异丁醇-苯酚体系的液液平衡研究。在常压下使用GC-14B气相色谱仪,测定了319K和329K时水-异丙醚-苯酚体系的液液平衡(LLE)数据以及水-异丁醇-苯酚体系在319K和333K时的LLE数据。用内标法测定了这些体系中除水以外的各组分浓度。在水-异丙醚-苯酚体系中,异丙醚测量的根均方误差为1.4%;苯酚测量的根均方误差为4.6%。在水-异丁醇-苯酚体系中,异丁醇测量的根均方误差为3.1%;苯酚测量的根均方误差为4.6%。文中给出了上述四个等温截面的LLE数据,同时也给出了相应示意图。2003年我们用工作曲线法(外标法)给出了水-异丙醚-苯酚在319K的等温截面图。两者比较,总体上是类似的,但内标法结果更可靠。这次的研究,还纠正了当时的一个错误估计。对于水-异丁醇-苯酚体系的液液平衡研究表明,异丁醇也是从废水中萃取苯酚的良好萃取剂。但是异丁醇的再生及其循环利用并不如异丙醚那样容易。

盐效分离作用理论预测

研究了盐效分离基本原理,采用选择性溶剂化模型,利用定标粒子理论计算盐在含水体系中的标准摩尔迁移自由能。提出了将迁移自由能与相平衡中盐效应的大小结合起来,用迁移自由能理论解释相平衡中的盐效应。文中计算了盐在6种含水体系的标准摩尔迁移自由能,并与其盐效应进行了对比,研究发现在含水体系中盐效应随盐的标准摩尔迁移自由能增大而增大,因此在盐效分离过程中可以采用标准摩尔迁移自由能模型选择有效的盐作分离剂。

烷烃-芳烃-N-甲酰吗啉体系液液平衡

用液液平衡釜测定了等温下正庚烷苯ＮＦＭ、甲基环己烷苯ＮＦＭ、正庚烷甲苯ＮＦＭ和甲基环己烷甲苯ＮＦＭ等４组三元体系的液液平衡数据，用ＮＲＴＬ和ＵＮＩＱＵＡＣ模型进行了关联，求得各三元体系的褶点数据，并对ＮＦＭ溶剂存在下烷烃和芳烃的选择性进行了比较。

无线局域网中业务流接入控制的博弈论算法

提出一种IEEE 802.11无线局域网中的用户流接入控制(AC)算法.通过建立用户流的QoS满意度(UQS)函数,将用户与接入点(AP)之间的接入控制决策过程建模为UQS最大化下的非协作博弈;根据此博弈的纳什均衡解,在不同的网络负载条件下,给出AP的最优接入控制策略(G-AC).仿真结果表明:G-AC算法能够为接入的用户流提供定量的QoS保证;并且,同传统的截止优先权AC算法(CP)相比,G-AC算法可以根据网络负载状况自适应的改变接纳策略,从而获取更高的带宽资源利用率(平均吞吐量高于CP算法10%),并为服务商带来更高的网络收益.

水-异丙醚-苯酚体系的液液平衡研究

用GC-14B气相色谱仪测定了水-异丙醚-苯酚体系在319K和329K的等温截面相图.经实验筛选,选择保留时间恰当和分离度较好的乙酰丙酮作为内标物,正丁醇作溶剂.实验测定了除水以外各组分的保留时间以及相对于乙酰丙酮的校正因子.测试了恒温振荡和静止时间对平衡浓度测定的影响.分别进行了回收率测量,确证本实验数据具有相当的可信度.用内标法测定了319K和329K两个等温截面的两相液液平衡实验数据,并给出了相应的相图示意图.对于319K,与以前用外标法测定的实验结果作了比较,内标法实验精确度提高,数据可信度提高.其主要相图特征是类似的.原来用外标法曾估计在异丙醚摩尔分数小于4%时,可能存在另一两相区域,是不正确的.用内标法测定的数据确切表明不存在另一两相区域.最后对实验误差进行了讨论.

水-异丙醚-苯酚-对苯二酚液液平衡数据的测定及关联

利用气相色谱测定了常压下 ,水 -异丙醚 -苯酚 -对苯二酚四元物系在 46℃时的液液平衡数据 ,采用峰面积归一化法定量 ,用NRTL模型对所测数据进行热力学关联 ,求出模型参数。可为工业生产提供参考数据。

豉香型白酒制曲原料中肉桂叶游离态挥发性成分

采用液液萃取与气相色谱-质谱联用技术,研究豉香型白酒制曲原料——肉桂叶中的挥发性成分。共分离并检测出45种挥发性化合物,包括25种芳香类、8种酚类、6种萜烯类、2种有机酸类、3种呋喃类以及1种吡喃类化合物。芳香族化合物在肉桂叶中种类较多,含量较高。定量结果分析表明,肉桂叶中反-肉桂醛(3.71mg/g干重)含量最高,其次为香豆素、2-苯乙醇、丁香醛、氢化肉桂酸内酯、苯甲醛等,这些物质是肉桂叶中的主要挥发性化合物,对肉桂叶乃至豉香型成品酒的风味影响较大。

甲基环己烷－苯－DMF－水液液平衡的研究

采用作者设计的液液平衡釜，于常压下测定了甲基环己烷（１）－ＤＭＦ（２）二元系（２０．０～４７．９℃）的互溶度数据，以及常压、２０．Ｏ℃和３５．Ｏ℃下甲基环己烷（１）－苯（２）－ＤＭＦ（３）三元系和甲基环己烷（１）－苯（２）－ＤＭＦ（３）－水（４）（ＤＭＦ／Ｈ２Ｏ＝４∶１，ｍａｓｓ比）四元系的ＬＬＥ数据。

Detection of geosmin and 2-methylisoborneol by liquid-liquid extraction-gas chromatograph mass spectrum (LLE-GCMS) and solid phase extraction-gas chromatograph mass spectrum (SPE-GCMS)

Two sample preparation methods were introduced and compared in this paper to establish a simple,quick and exact analysis of geosmin and 2-methylisoborneol.LC-18 column was employed in solid phase extraction(SPE),1.0 mL of hexane was adopted in liquid-liquid extraction(LLE),and the extracts were analyzed by gas chromatograph mass spectrum(GCMS)in selected ion mode.Mean recoveries of SPE were low for 2-methylisoborneol(2-MIB)and geosmin(GSM)with values below 50%.For LLE,the recoveries were satisfyingly above 50%for 2-MIB and 80%for GSM.Detection limits of the LLE method were as low as 1.0 ng/L for GSM and 5.0 ng/L for 2-MIB.A year-long investigation on odor chemicals of drinking water in Shanghai demonstrated that in the summer,there was a serious odor problem induced by a high concentration of 2-MIB.The highest concentration of 152.82 ng/L appeared in July in raw water,while GSM flocculation was minimal with concentrations below odor threshold.