基于COSMO-RS方法筛选离子液体分离乙酸乙酯-乙腈共沸物

采用COSMO-RS方法探究了不同离子液体在分离乙酸乙酯-乙腈共沸物系中的应用;通过预测值与实验值的对比,验证了COSMO-thermX预测离子液体分离效果的准确性。离子液体的选择性和不同离子液体对乙酸乙酯-乙腈近沸点处相对挥发度的影响为指标,计算和分析了17种阳离子和13种阴离子组成的221种离子液体对乙酸乙酯-乙腈共沸物系的分离效果的影响规律。结果表明,含有[OAc]^－和[Cl]^－的离子液体对于乙酸乙酯-乙腈混合物的分离具有更好的促进效果,而阳离子的变化对于乙酸乙酯-乙腈混合物分离的促进效果差异较小。应用表面电荷密度分布（σ-profile）进一步研究了阴离子[OAc]^－和[Cl]^－对共沸物的影响,研究发现,阴离子[OAc]^－和[Cl]^－对乙酸乙酯-乙腈的分离效果影响顺序为[OAc]^－>[Cl]^－;综合筛选结果,得出离子液体[BMIM][OAc]有望在乙酸乙酯-乙腈共沸混合物分离过程中成为一种高效的萃取剂。     

High capacity absorption of SO2 using imidazole ionic liquid mixtures

The capture of sulfur dioxide (SO₂) with readily available and cost-effective ionic liquids (ILs) is one of the challenges for the application of ILs. Here, we synthesized the ILs mixtures with different molar ratios (3∶1, 2∶1, 1∶1, 1∶2, and 3∶1) of 1-ethyl-3-methylimidazolium chloride ([Emim][Cl]) and 1-ethyl-3-methylimidazolium acetate ([Emim][OAc]) to study their SO₂ absorption capacities. The SO₂ solubilities in these mixtures were investigated under different conditions. The SO₂ absorption capacities of [Emim][Cl]_x[OAc]_1-x at different temperatures and SO₂ partial pressure were measured. The results show that ILs can effectively capture SO₂. There exists a synergistic promotion effect between [Emim][Cl] and [Emim][OAc], resulting in quite high SO₂ absorption capacity. The [Emim][Cl]_0.33[OAc]_0.66 mixture can capture SO₂ (1.34±0.08) and (0.74±0.05) g/g at 1.0 and 0.2 atm(1 atm=101325 Pa), respectively. Comparing with the reported data, [Emim][Cl]_x[OAc]_1-x mixtures show obvious advantage for SO₂ capture. In addition, these ionic liquid mixtures have good reversibility for the absorption and desorption of sulfur dioxide.     

咪唑类离子液体混合物用于二氧化硫高效吸收

开发易制备、价格便宜、面向SO₂气体高效分离的离子液体（ILs）,是当前ILs从实验探索迈向工业应用的难点与重大挑战。合成了不同摩尔比（3∶1、2∶1、1∶1、1∶2和1∶3）的1-乙基-3-甲基咪唑氯盐（[Emim][Cl]）和1-乙基-3-甲基咪唑乙酸盐（[Emim][OAc]）的离子液体混合物[Emim][Cl]_x[OAc]_1-x, 在测定其密度、黏度、热稳定性等基本物性数据的基础上,研究了[Emim][Cl]_x[OAc]_1-x混合物在不同温度和SO₂分压下的SO₂吸收能力。结果表明,[Emim][Cl]_x[OAc]_1-x能够有效地捕获SO₂。[Emim][Cl]与[Emim][OAc]之间存在协同促进作用,有利于实现SO₂高效吸收。[Emim][Cl]_0.33[OAc]_0.66混合液在1.0和0.2 atm（1 atm=101325 Pa）下捕获SO₂量分别为（1.34±0.08）和（0.74±0.05） g/g,与现有结果相比,混合物在SO₂捕获方面有明显优势。此外,这些离子液体混合物对二氧化硫的吸收和解吸具有良好的可逆性。     

油酚分离过程离子液体萃取溶剂的多尺度筛选

离子液体作为萃取溶剂已广泛用于油酚混合物的分离,但由于阴阳离子的可调控性,不同离子液体的性质差异较大,快速筛选得到具有应用前景的离子液体至关重要。针对间甲酚-异丙苯分离体系,采用COSMO-RS模型考察不同阴阳离子结构对离子液体分离性能的影响,并通过分子间相互作用能进行分析。在此基础上,提出一种多尺度的离子液体筛选方法,该方法包含无限稀释热力学性质计算、物性估算、相平衡关系计算和过程性能评价。该多尺度方法从分子尺度到单级平衡尺度,再到多级平衡尺度对离子液体进行逐步筛选。结果表明,1-乙基吡啶硫氰酸盐([C₂py][SCN])和1-乙基吡啶双氰胺盐([C₂py][DCA])是最终筛选得到的两种更具有油酚分离应用前景的离子液体。     

离子液体的电导性质研究进展

离子液体(ILs)具有优异的导电能力,其电导性质不仅是电化学应用的基础,而且广泛用于研究ILs溶液热力学性质与微观结构。本文首先总结了近年来实验测定法在研究纯ILs、ILs+溶剂和ILs+ILs体系电导率(κ)或摩尔电导率(Λ)等方面取得的进展,详细讨论了ILs结构、ILs浓度、温度等因素对体系κ或Λ的影响,并结合溶液热力学模型分析了ILs κ或Λ的变化规律。在此基础上,重点介绍了电导性质在研究纯ILs的离子率以及ILs+溶剂体系微观结构和相互作用方面的应用及进展。最后,对ILs电导性质研究与应用提出了几点建议。     

离子液体修饰超顺磁性纳米颗粒用于青霉素G酰化酶固定化(英文)

Functionalized ionic liquids containing ethyoxyl groups were synthesized and immobilized on magnetic silica nanoparticles(MSNP) prepared by two steps,i.e.,Fe3O4 synthesis and silica shell growth on the surface.This magnetic nanoparticle supported ionic liquid(MNP-IL) were applied in the immobilization of penicillin G acylase(PGA).The MSNPs and MNP-ILs were characterized by the means of Fourier transform infrared spectroscopy(FTIR),scanning electron microscopy(SEM),transmission electron microscopy(TEM),and vibrating sample magnetometer(VSM).The results showed that the average size of magnetic Fe3O4 nanoparticles and MSNPs were ~10 and ~90 nm,respectively.The saturation magnetizations of magnetic Fe3O4 nanoparticles and MNP-ILs were 63.7 and 26.9 A?m2?kg?1,respectively.The MNP-IL was successfully applied in the immobilization of PGA.The maximum amount of loaded enzyme was about 209 mg?g?1(based on carrier),and the highest enzyme activity of immobilized PGA(based on ImPGA) was 261 U?g?1.Both the amount of loaded enzyme and the activity of ImPGA are at the same level of or higher than that in previous reports.After 10 consecutive operations,ImPGA still main-tained 62% of its initial activity,indicating the good recovery property of ImPGA activity.The ionic liquid modified magnetic particles integrate the magnetic properties of Fe3O4 and the structure-tunable properties of ionic liquids,and have extensive potential uses in protein immobilization and magnetic bioseparation.This work may open up a novel strategy to immobilize proteins by ionic liquids.     

COSMO-RS modeling on the extraction of stimulant drugs from urine sample by the double actions of supercritical carbon dioxide and ionic liquid

This work presents the first research linking chemical engineering and sport science as far as we know. The COSMO-RS (conductor-like screening model for real solvents) model was used to make a priori prediction for the extraction of stimulants from aqueous solution by the double action of supercritical carbon dioxide (SC CO₂) and ionic liquid. It was found that the suitable ionic liquids should have small molecular volume, unbranched group and no sterical shielding effect around anion charge center, and thus [C₂MIM]⁺[OAc]^- is the best among all the ionic liquids investigated. The calculated results from the COSMO-RS model were qualitatively consistent with those from experiments. On this basis, partition coefficients of amphetamine (C9N) and nikethamide (C10N) between aqueous phase and supercritical fluid (or MTBE) phase at different temperatures were calculated. It was shown that the separation efficiency of supercritical extraction with ionic liquid is generally higher than that of traditional liquid-liquid extraction. The modeling present can also be extended to the separation of trace amount of organic substances from aqueous solutions for other purposes.     

Analytical Expressions for the Heat Capacities of Alkali Silicate Liquids

The available thermochemical data for silicate liquids and glasses indicate that the customary assumption of heat-capacity additivity is not valid, particularly for liquid silicates near 1000 K. Estimates are obtained for the heat capacities of KO_0.3-SiO₂, NaO_0.3-SiO₂, and CaO-SiO₂ liquids. The excess heat capacity of mixing of alkali silicates at 1000 K is:
in units of cal mol⁻¹ K⁻¹. Analytical expressions are given for C ^e_p for KO_0.5-NaO_0.5-SiO₂ and NaO_0.3-CaO-SiO₂ liquids at 900 to 1800 K.     

Solubility and mass transfer of H2, CH4, and their mixtures in vacuum gas oil: An experimental and modeling study

In this work, the solubility data and liquid-phase mass transfer coefficients of hydrogen (H₂), methane (CH₄) and their mixtures in vacuum gas oil (VGO) at temperatures (353.15-453.15 K) and pressures (1-7 MPa) were measured, which are necessary for catalytic cracking process simulation and design. The solubility of H₂ and CH₄ in VGO increases with the increase of pressure, but decreases with the increase of temperature. Henry's constants of H₂ and CH₄ follow the relation of ln H=-413.05/T + 5.27 and ln H=-990.67/T + 5.87, respectively. The molar fractions of H₂ and system pressures at different equilibrium time were measured to estimate the liquid-phase mass transfer coefficients. The results showed that with the increase of pressure, the liquid-phase mass transfer coefficients increase. Furthermore, the solubility of H₂ and CH₄ in VGO was predicted by the predictive COSMO-RS model, and the predicted values agree well with experimental data. In addition, the gas-liquid equilibrium (GLE) for H₂ + CH₄ + VGO system at different feeding gas ratios in volume fraction (i.e., H₂ 85% + CH₄ 15% and H₂ 90% + CH₄ 10%) was measured. The selectivity of H₂ to CH₄ predicted by the COSMO-RS model agrees well with experimental data. This work provides the basic thermodynamic and dynamic data for fuel oil catalytic cracking processes.     

MULTICOMPONENT POLYMER/SOLVENTS EQUILIBRIA: AN EVALUATION OF FLORY-HUGGINS THEORY FOR CROSSLINKED PDMS NETWORKS SWELLED BY BINARY MIXTURES

The prediction of equilibrium volume fractions of solvents mixtures in a polymer network is of utmost importance for processes dealing with polymeric materials (e.g. chromatographic and membrane processes). Up to now, few studies have studied the ability of existing theories to predict experimental multicomponent sorption data in polymers; this work intends to achieve that purpose on model liquid mixtures in contact with silicone rubber (polydimethylsiloxane). The equilibrium volume fractions of three liquid mixtures (chloroform/toluene; ethanol/toluene; ethanol/2-butanol) in crosslinked PDMS samples have been determined experimentally at 40^°C. Results are compared to predictions by the Flory-Huggins theory applied to ternary mixtures (one polymer and two liquids) with constant interaction parameters and negligible elastic contribution. Solvent/polymer interaction parameters have been determined by swelling the crosslinked samples in pure liquids, while liquid/liquid interaction parameters have been estimated from liquid/vapor equilibrium data. It is shown that the Flory-Huggins theory offers good predictions in the case of good (chloroform, toluene) and fair (2-butanol) PDMS solvents, while significant discrepancies are obtained with a non solvent (ethanol). Implications in ternary diagrams simulation and possible prediction improvements, based on non constant interaction parameters, are discussed.     

Heat Capacity and Structural Relaxation of Mixed-Alkali Glasses

Heat capacities of a series of mixed-alkali glasses of composition (in mol%) 24.4(Na₂O + K₂O)-75.6SiO₂ were measured in the transition region by differential scanning calorimetry. The glass heat capacities at 700 K and the equilibrium liquid heat capacities are the same for all glasses on a per-g atom basis and equal, respectively, to 5.6 ± 0.1 and 6.8 ± 0.1 cal/g atom K. The glass transition temperatures exhibited negative deviations from additivity, but the heat capacity curves in the transition region of all the glasses for identical heating rates and thermal histories could be superimposed on the same reduced plot. This behavior indicates that the shapes of the structural relaxation functions are the same for all the glasses. These results support Shelby's conclusion that there is no unique "mixed-alkali effect" on thermodynamic or structural relaxation properties and that the term should be reserved for properties relating to ionic transport.     

CO2-烃类液相混合物比定容热容的实验与模型研究

近年来,二氧化碳(CO₂)提高原油采收率(CO₂-EOR)技术得到了广泛的研究。充分了解CO₂-烃类混合物的热容性质是该项目能够成功实施的基础,但是目前对此性质的研究非常有限。基于绝热量热法,搭建了一个绝热量热计,测量了温度为317.15~353.15 K,压力高达29.49 MPa时,CO₂-碳氢化合物(正己烷、正辛烷、十一烷、环己烷、乙苯)二元液相混合物的比定容热容(C_v )数据,共获得335个数据点。此外,采用预测模型(结合热力学关系的PR状态方程)和经验模型计算C_v,计算平均绝对相对偏差(AARD)分别为0.81%~3.66%和小于2.56%。经验模型的形式简单,但PR模型有较强的预测能力。实验测得的C_v 数据以及建立的两种计算模型对CO₂-EOR项目的实施至关重要。     

微通道内超临界氮气三维热流场实验与数值模拟

利用实验与数值模拟相结合的方法研究了超临界氮气（SCN₂）三维热流场特性，在用实验数据验证数值方法可靠性基础上，分析了压力（3.6~7 MPa）和质量流速［800~1200 kg/（m²?s）］对SCN₂对流传热特性的影响，揭示了微通道圆管不同圆周方向上SCN₂热流场规律。结果表明：在低压力和高质量流速下，同一轴向位置处，径向内壁温最大值出现在圆管90°处；质量流速越大，内壁温最大值和对流传热系数最小值由圆管180°向90°处发生了转移；当浮升力系数Gr*/Re²>1时，浮升力有利于强化圆管底部区域流体传热能力；基于获得的数据，提出了一个新的适合预测微通道圆管内SCN₂对流传热特性的无量纲换热关联式，预测误差小于20%。研究结果为微通道换热器优化设计提供了参考。     

Particle collision behavior and heat transfer performance in a Na2SO4 circulating fluidized bed evaporator

The particle collision behavior and heat transfer performance are investigated to reveal the heat transfer enhancement and fouling prevention mechanism in a Na₂SO₄ circulating fluidized bed evaporator. The particle collision signals are analyzed with standard deviation by varying the amount of added particles ε (1%–3%), circulation flow velocity u (0.37–1.78 m·s^-1), and heat flux q (7.29–12.14 kW·m^-2). The results show that the enhancement factor reach up to 14.6% by adding polytetrafluoroethylene particles at ε = 3%, u = 1.78 m·s^-1, and q = 7.29 kW·m^-2. Both the standard deviation of the particle collision signal and enhancement factor increase with the increase in the amount of added particles. The standard deviation increases with the increase in circulation flow velocity; however, the enhancement factor initially decreases and then increases. The standard deviation slightly decreases with the increase in heat flux at low circulation flow velocity, but initially increases and then decreases at high circulation flow velocity. The enhancement factor decreases with the increase in heat flux. The enhancement factor in Na₂SO₄ solution is superior to that in water at high amount of added particles. The empirical correlation for heat transfer is established, and the model results agree well with the experimental data.     

基团贡献法估算离子液体的静态介电常数简

Static dielectric constant is a key parameter to estimate the electro-viscous effect which plays important roles in the flow and convective heat transfer of fluids with ions in microfluidic devices such as micro reactors and heat exchangers. A group contribution method based on 27 groups is developed for the correlation of static dielectric constant of ionic liquids in this paper. The ionic liquids considered include imidazolium, pyridinium, pyrrolidinium, alkylammonium, alkylsulfonium, morpholinium and piperidinium cations and various anions. The data collected cover the temperature ranges of 278.15 343.15 K and static dielectric constant ranges of 9.4 85.6. The results of the method show a satisfactory agreement with the literature data with an average absolute relative deviation of 7.41%, which is generally of the same order of the experimental data accuracy. The method proposed in this paper provides a simple but reliable approach for the prediction of static dielectric constant of ionic liquids at different temperatures.     

One‐ and two‐phase isochoric heat capacity measurements of aqueous solution of nacl near the critical point of pure water

Isochoric heat capacities of H₂O+NaCl solutions (0.0031 and 0.0063 mole fraction of NaCl) were measured with a high temperature and high pressure adiabatic calorimeter near the sub‐critical and near the supercritical point of pure water. Temperatures ranged from 361 to 677 K. Measurements were made at six densities, namely: 367.07 and 485.59 kg·m^?3 for x = 0.0031 mol fraction of NaCl and 388.65, 560.03, 607.05, and 973.70 kg·m^?3 for x = 0.0063 mol fraction of NaCl. Measurements were conducted in the two‐and one‐phase regions including near phase transition temperatures T_S(ρ). The phase transition temperatures T_S(ρ) and saturated isochoric heat capacity values C_VX have been determined for each isochore. The uncertainty in heat capacity measurements is estimated to be 3.5% to 4.5% near the phase transition and critical points. Present and previous results of heat capacity measurements were compared with predictions from the crossover (CREOS) and Pitzer—Tanger–Hovey equations of state (PTH EOS). Our previous heat capacity measurements were found to deviate systematically from crossover‐model predictions. The present results show good agreement with the crossover model for the composition x = 0.0031 mol fraction.     

基团贡献法预测离子液体的折射率

基于对离子液体折射率的研究,提出了一种基团贡献法来预测不同温度下离子液体的折射率数值。通过文献搜集了115种离子液体,涵盖5类阳离子和26类阴离子,然后使用新的基团划分方法,共得到39种基团。将115种离子液体的1 161个折射率（λ=589 nm）数据点与模型方程回归,得到了各个基团的贡献值,回归的标准方差为0.00897,平均相对偏差为0.452%。为了进一步检验模型的准确性,用其估算未参与回归的2种代表性离子液体：季铵盐和季鏻盐,得到的平均相对偏差分别为0.520% 和0.284%,说明使用该基团贡献法来预测不同温度下离子液体的折射率是可靠的。     

Property estimation using structural characterizations: Heat capacities of coal liquids

Three coal liquids were characterized by estimating the concentrations of the functional groups present in the liquids. The concentrations were deduced using data from Chromatographic separations, elemental analysis, ¹H n.m.r., ¹³C n.m.r. and mass spectrometry. The concentration estimates were then used, in conjunction with simple group additivity rules, to estimate the heat capacities of the liquids as a function of temperature. The heat capacity estimates were in excellent agreement with experimentally determined values.     

Low-pressure CO2 sorption in ammonium-based poly(ionic liquid)s

Ammonium-based ionic liquid monomers and their corresponding polymers [poly(ionic liquid)s] are synthesized and characterized for CO₂ sorption. The polymers have much higher CO₂ sorption capacities than the room-temperature ionic liquids and imidazolium-based poly(ionic liquid)s. For example, P[VBTMA][PF₆] with polystyrene backbone has a CO₂ sorption capacity of 10.67 mol%. The CO₂ sorption is selective over N₂ and O₂. The effects of cation, backbone, substituent, anion and crosslinking on CO₂ sorption are discussed. The sorption mechanism study indicates that CO₂ sorption by the poly(ionic liquid)s is a bulk and surface phenomenon.     

Modeling of CO2 Solubility in Selected Imidazolium-Based Ionic Liquids

This study explores the use of COSMO-RS model and Peng-Robinson (PR) equation of state (EoS) to predict the solubility of carbon dioxide (CO₂) in specific ionic liquids (ILs). COSMO-RS was employed to estimate of CO₂ solubility at atmospheric pressure in eight imidazolium-based ILs resulting from the combination of ethyl, butyl, hexyl, and octyl-imidazolium cations with two anions: bis(trifluoromethylsulfonyl)imide ([Tf₂N]) and Trifluoromethanesulfonate ([TFO]). The results indicated relatively acceptable qualitative consistency between the experimental and predicted values. The PR EoS was employed at high pressure by tuning the interaction parameters to fit the experimental data reported in the literature. The model demonstrated excellent accuracy in predicting the solubility of CO₂ at pressure values less than the critical pressure of CO₂; however, at higher pressures, the calculated solubility diverged from the experimental values. Furthermore, the type of anion and cation used in the IL affected the performance of the PR EoS.