高粘度液体真空搅拌脱泡理论分析与计算

真空搅拌脱泡是高粘度液体的一种有效脱泡方式。对于高粘度液体中的气泡,单靠自身的浮力上升,其速度是极其缓慢的,搅拌槽内生成的气泡主要依靠搅拌被带到近液面而逸出。建立了搅拌流场中的气泡运动方程,获得了气泡在流场中的相对运动速度。计算了气泡从液面逸出的总时间。真空搅拌脱泡过程主要发生在液面,论文分析了搅拌槽内真空度大小、主流体循环到液面的次数和主流体在液面停留时间对脱泡的影响。为保证气泡在近液面有足够的停留时间挣脱液面张力,必须要有一个合理搅拌转速。     

磁性离子液体的制备与应用研究进展

磁性离子液体是一种新型的功能化离子液体材料,具有优良的热稳定性、优异的电化学性能、良好的溶解性能以及可回收性等特性,使其在萃取分离、反应催化和复合材料等领域具有较好的应用前景。对目前合成的磁性离子液体做了概述并根据构效关系对主要的磁性离子液体进行了分类。综述了磁性离子液体的主要制备方法,主要有一步合成法、二步合成法和辅助合成法。介绍了磁性离子液体在萃取分离、反应催化及碳纳米管复合材料领域应用研究进展。最后根据磁性离子液体在合成和应用中的不足做了展望。     

离子液体在萃取分离中的应用进展

作为环境友好型功能材料——离子液体以其独特的物理化学性质已引起人们的广泛关注。离子液体在萃取分离有机物、无机金属离子领域的应用越来越多。概述了离子液体在萃取分离中的应用。总结了离子液体的萃取机理,介绍了离子液体的结构如阴、阳离子的类型对萃取效率的影响规律,讨论了静电作用、疏水作用、氢键等作用力在萃取分离过程中所扮演的角色。最后展望了离子液体在萃取分离领域的发展方向。     

离子液体的合成与纯化方法研究进展

综述了离子液体的种类、合成及纯化方法。离子液体的纯度对其物理化学性质至关重要,是研究其应用的首要问题。本文介绍了离子液体的合成方法,并对比了其优缺点,发现合成方法对离子液体的纯度起着关键作用,指出了影响离子液体纯度的因素,分析对比了离子液体的纯化方法,包括真空干燥、有机溶剂萃取、重结晶、吸附剂法、分子筛法等,根据影响因素种类的不同,优选纯化方法,并对离子液体的发展进行了展望。     

离子液体中不同形貌硫化镉的合成及光催化活性

以硝酸镉和硫代乙酰胺为原料,在不同的离子液体水溶液中采用超声法合成了不同形貌的硫化镉。采用XRD、SEM、BET、紫外-可见吸收光谱等手段对样品的结构和光学性能进行了考察,以罗丹明B为目标降解物考察了不同形貌硫化镉的光催化性能。结果表明,在不同的离子液体水溶液中可分别得到粒状、棒状和粒棒混合体。对比了纳米粒子、纳米棒和粒棒混合体对罗丹明B的降解率,结果表明,CdS纳米粒子具有更高的光催化效率,其粒状硫化镉比表面积为79.5m2/g,远大于其它形状的硫化镉。在紫外光和可见光的照射下,反应120min罗丹明B的降解率分别为97%和30%。离子液体的特殊结构是粒状硫化镉具有较高光催化活性的原因。     

离子液体/磷酸锆抗菌材料的制备及耐热性研究

以α-磷酸锆(分子式: Zr(HPO₄)₂·H₂O, 以下简称α-ZrP)为载体, 三种季铵型离子液体: 溴化十六烷基三甲基咪唑(C₁₆MIMBr)、氯化十六烷基二甲基苄基铵(C₁₆HDBACCl)和氯化十六烷基三甲基铵(C₁₆CTACCl)被引入α-ZrP层间, 制备得到三种离子液体/α-磷酸锆(IL-ZrP)复合抗菌材料. 通过X射线衍射法(XRD)、红外光谱分析(FTIR)、热重-红外联用分析(TG-FTIR)对材料的结构、组成和热稳定性进行表征. XRD结果表明: 相对于α-ZrP, 三种复合抗菌材料的层间距明显增大, 这证明离子液体已经成功地嵌入到α-ZrP的层间. TG-FTIR实验显示三种离子液体在复合抗菌材料中分别占53.11wt%、50.65wt%和51.25wt%. 三种纯离子液体的热分解起始温度分别为174℃、198℃和219℃, 而离子液体/α-ZrP(IL-ZrP)复合抗菌材料中所含的离子液体的热分解起始温度为219℃、225℃和263℃, 这表明α-ZrP能有效提高离子液体的耐热性. 抗菌性能检测结果表明: 在三种复合材料中, C₁₆MIMBr-ZrP具有较好的抗菌效果(在24 h内, 其对大肠杆菌、金色葡萄球菌的最小抑菌浓度均小于19 mg/L).     

Estimation of Density as a Function of Temperature and Pressure for Imidazolium-Based Ionic Liquids Using a Multilayer Net with Particle Swarm Optimization

The liquid density of imidazolium-based ionic liquids has been estimated using a combined method that includes an artificial neural network and a simple group contribution method. A total of 1736 data points of density at several temperatures and pressures, corresponding to 131 ionic liquids, have been used to train the neural network developed with particle swarm optimization. To discriminate among the different substances, the molar mass and the structure of the molecule were given as input variables. Then, new values of density as a function of temperature and pressure for 33 other ionic liquids (426 data points) have been predicted and the results compared to experimental data from the literature. The results show that the chosen artificial neural network with particle swarm optimization and the group contribution method represent an excellent alternative for the estimation of the liquid density of imidazolium-based ionic liquids with acceptable accuracy (AARD=0.44; R ² = 0.9934), for a wide range of temperatures and pressures (258 K to 393K and 99kPa to 206,940kPa).     

Molecular Insights into the Regulatable Interfacial Property and Flow Behavior of Confined Ionic Liquids in Graphene Nanochannels

The understanding of confined structure and flow property of ionic liquid (IL) in a nanochannel are essential for the efficient application of ILs in the green chemical processes. In this work, the ionic structure and various flow behaviors of ILs inside graphene nanochannels via molecular dynamics simulations are shown. The effect of the nanochannel structure on confined flow is explored, showing that the width mainly heightens the viscosity while the oxidation degree primarily enhances the interfacial friction coefficient. Tuning the width and oxidation degree of nanochannel, three different flow behaviors including Poiseuille, partial plunger and full plunger flow can be achieved, where the second one does not occur in water or other organic solvents. To describe the special flow behavior, an effective influence extent of the nanochannel (w _EIE) is defined, whose value can distinguish the above flows effectively. Based on w _EIE, the phase diagrams of flow behavior for the nanochannel structure and pressure gradient are obtained, showing that the critical pressure gradient decreases with width and increases with the oxidation degree. Based on the quantitative relations between confined structures, viscosity, friction coefficient, flow behavior, and nanochannel structure, the intrinsic mechanism of regulating the flow behavior and rational design of nanochannel are finally discussed.     

Viscosity and density of binary mixtures of cyclohexane with n-octane,n-dodecane,and n-hexadecane under high pressures

The viscosity and density of three binary mixtures of cyclohexane with n-octane, n-dodecane, and n-hexadecane have been measured at 298, 323, and 348 K at pressures up to 150 MPa or freezing pressures. The measurements of the viscosity were performed by a torsionally vibrating crystal viscometer on a relative basis using benzene and cyclohexane as reference materials. The density was measured using a high-pressure burette apparatus. The uncertainties of the measurements are estimated to be less than 2% for viscosity and 0.1% for density, respectively. The effects of temperature, pressure, density, and composition on the viscosity are discussed. Applicabilities of several empirical correlating equations to the viscosity data were examined.     

含咪唑聚离子液体的星型POSS嵌段共聚物基阴离子交换膜的制备与性能

以聚甲基丙烯酸甲酯嵌段聚乙烯基咪唑为臂,低聚倍半硅氧烷(POSS)为核的星型嵌段共聚物POSS-(PMMA-bPVIm)8为基膜材料,通过季铵化反应和离子交换过程对其进行改性,制备2种咪唑聚离子液体嵌段不同的阴离子交换膜,分别记作PMV-1、PMV-2,研究其吸水率、溶胀度、离子交换容量、力学性能、电导率及耐碱性。结果表明,膜在90℃时仍保持适当的吸水强度,2种膜的吸水率分别为18.09%和25.81%,厚度方向溶胀度分别为25.31%,35.45%;30℃时PMV-1、PMV-2的离子交换容量分别为2.38 meq/g,3.12 meq/g,力学性能良好;2种膜室温下均已具有良好的离子传输性能,90℃时电导率分别达44.02 m S/cm和255.0 m S/cm;耐碱性测试表明,含聚离子液体嵌段较短的膜PMV-1稳定性较好,60℃强碱溶液中浸泡120 h后电导率下降不超过30%。     

25th Anniversary Article: “Cooking Carbon with Salt”: Carbon Materials and Carbonaceous Frameworks from Ionic Liquids and Poly(ionic liquid)s

This review surveys recent work on the use of ionic liquids (ILs) and polymerized ionic liquids (PILs) as precursors to synthesize functional carbon materials. As solvents or educts with negligible vapour pressure, these systems enable simple processing, composition, and structural control of the resulting carbons under rather simple and green synthesis conditions. Recent applications of the resulting nanocarbons across a multitude of fields, such as fuel cells, energy storage in batteries and supercapacitors, catalysis, separation, and sorption materials are highlighted.     

Reduction of DNA Folding by Ionic Liquids and Its Effects on the Analysis of DNA–Protein Interaction Using Solid‐State Nanopore

DNA folding is not desirable for solid‐state nanopore techniques when analyzing the interaction of a biomolecule with its specific binding sites on DNA since the signal derived from the binding site could be buried by a large signal from the folding of DNA nearby. To resolve the problems associated with DNA folding, ionic liquids (ILs), which are known to interact with DNA through charge–charge and hydrophobic interactions are employed. 1‐n‐butyl‐3‐methylimidazolium chloride (C₄mim) is found to be the most effective in lowering the incident of DNA folding during its translocation through solid‐state nanopores (4–5 nm diameter). The rate of folding signals from the translocation of DNA–C₄mim is decreased by half in comparison to that from the control bare DNA. The conformational changes of DNA upon complexation with C₄mim are further examined using atomic force microscopy, showing that the entanglement of DNA which is common in bare DNA is not observed when treated with C₄mim. The stretching effect of C₄mim on DNA strands improves the detection accuracy of nanopore for identifying the location of zinc finger protein bound to its specific binding site in DNA by lowering the incident of DNA folding.     

无机盐/离子液体对再生纤维素结构与性能的影响

合成了一种离子液体1-烯丙基-3-甲基咪唑亚磷酸甲酯盐([Amim][(MeO)PHO_2]),这种离子液体能很好地溶解纤维素,并加入与其阴离子结构类似的无机盐亚磷酸氢二钠(Na_2PHO_3)组成复合溶解体系。文中研究了离子液体和复合体系对纤维素结构与性能的影响,通过对原生和再生纤维素展开红外光谱、热重分析、X射线衍射及聚合度的测试表征,结果显示再生纤维素没有发生衍生化,但热稳定性和结晶度及聚合度均比原生纤维素低,且随着复合溶解体系中Na_2PHO_3含量的增大,从中再生出来的纤维素的聚合度越高、热降解温度越高、结晶度越低。这种结果可能是由于无机盐的加入降低了离子液体对纤维素的酸降解而导致的。     

"枣糕状"结构杂多酸离子液体负载磁性复合材料的制备及超声脱硫的催化性能

石油中的含硫化合物不仅影响油品质量,其燃烧生成的硫氧化物(SOx)还会对生态环境和人类健康构成极大威胁.此外,燃油中的硫化物燃烧使得燃油尾气处理设备中催化剂中毒,从而排放一些其他有害的汽车尾气,如氮氧化物(NOx)、碳氢化合物和一氧化碳(CO)等.为了降低燃油中的硫含量,世界各国政府都颁布了严格的标准,如美国环保署在2006年将柴油中的硫含量降低到15 mg/kg;2007年欧盟和日本将柴油中的硫含量上限设定为10 mg/kg.自2017年起,我国政府发布了国V标准,将柴油中的硫含量限制在10 mg/kg以下.随着各项政策的出台,如何通过高效深度脱硫技术降低石油中的硫含量已成为石油化工领域的研究热点.同时,超深脱硫在解决工业废物再利用中也发挥着重要作用.目前常用的深度脱硫的方法主要有加氢脱硫(HDS)和非加氢脱硫(NHDS).由于传统的HDS方法存在去除噻吩类物质困难、成本高、条件苛刻、耗时耗能等缺点,NHDS以其低能耗、环保等优点逐渐受到人们的青睐.NHDS技术包括氧化脱硫、吸附脱硫、萃取脱硫和生物脱硫等.其中,氧化脱硫可以通过氧化剂将有机硫化物转化为砜或亚砜,提高有机硫化物在极性溶剂中的溶解度,通过萃取和蒸馏等方法将有机硫化物从石油中分离出来,达到深度脱硫的目的.与机械搅拌、生物或光催化氧化脱硫等传统脱硫方法相比,超声辅助氧化脱硫法是反应时间最短、效率最高的方法之一.近年来,离子液体因良好的热稳定性和化学稳定性而受到越来越多的关注,并被广泛应用于催化氧化脱硫.在杂多酸中引入离子液体可以形成具有氧化活性中心的杂多酸离子液体,有望表现出优异的催化活性.Xun等采用溶胶-凝胶法制备了杂多酸离子液体催化剂(SiW12O40-IL),该催化剂在脱硫方面具有优异的催化活性,当温度为60℃,n(O)/n(S)为4时,其脱硫率达到99.9％.然而,作为均相催化剂,杂多酸离子液体也存在回收率低、可重复利用性差等缺点,因此选择合适的固载化方法,实现杂多酸离子液体催化剂的异相化十分关键.常用的载体有SiO2、Al2O3、Fe3O4等,其中磁性复合材料可以实现催化剂和油样在磁场作用下的快速分离,已成为目前最为流行的载体之一.将磁性复合材料通过改性结合到催化剂上,有望得到具有较高的脱硫催化活性和优异分离效果的催化剂.为此,本研究设计并成功合成了一种具有"枣糕状"结构的、杂多酸离子液体[BMIM]3 PW12O40负载的三乙烯四胺(TETA)功能化的Fe3O4复合材料([BMIM]3 PW12O40/Fe3O4@TETA).以正辛烷为模拟油样,二苯并噻吩为硫源,过氧化氢为氧化剂,[BMIM]3PW12O40/Fe3O4@TETA为催化剂,通过超声协助考察了催化剂的催化氧化脱硫.采用响应面法(RSM)研究了超声时间、H2O2用量、反应温度对催化剂脱硫的影响;并考察了催化剂的稳定性和再生性能.对[BMIM]3PW12O40/Fe3O4@TETA的脱硫机理进行了初步探讨,结果表明,采用0.025 g[BMIM]3PW12O40/Fe3O4@TETA对50 mL浓度为500 mg/g的二苯并噻吩的模拟油样进行脱硫实验时,最佳脱硫条件为:反应温度325 K,超声时间15 min,n(O):n(S)=8:1,脱硫率可达96.5％.该催化剂重复使用五次后,脱硫率仍保持在93.7％,表明[BMIM]3PW12O40/Fe3O4@TETA具有良好的催化脱硫性能,可以重复使用.初步的脱硫机理研究表明,[BMIM]3PW12O40/Fe3O4@TETA的催化活性中心可能为其含有的杂多酸阴离子;Fe3O4@TETA起到载体的作用,而离子液体起到协同增强作用.     

Ionic Liquids Assisted Synthesis of ZnO Nanostructures:Controlled Size,Morphology and Antibacterial Properties

Systematic analysis about the exploitation of imidazolium based ionic liquids（ILs）,[BMIM]BF₄[IL1],[EMIM]BF₄ [IL2]and[BMIM]PF₆[IL3]as the morphological template on the basic sol-gel method adopted synthesis of nanostructured zinc oxide（ZnO） is presented.X-ray diffraction（XRD）,particle size analysis（PSA） and scanning electron microscopy（SEM） have been employed for the characterization of structure and morphology of the synthesized ZnO particles.Well-defined capsule like shaped morphology with lower nanosize is observed for the ZnO nanoparticles with IL1 than those with IL2 and IL3.This confirms that IL1 served as an effective templating material due to their unique properties.Especially the effective aggregation of ZnO particles with a self-organized frame of IL1 was the essential factor to produce the lower nanosized ZnO with capsule shaped structure.The synthesized ZnO samples with IL2 and IL3 fabricated the flake like shaped and rod like shaped morphologies in the range of nanoscale.The formed ZnO nanoparticles with IL2 exhibit higher nanosize than the ZnO nanoparticles produced by IL1,owing to shorter length of alkyl group in its cation which restricts steric effect and permits the nanoparticles to grow longer.Even though IL3 produced the discrete ZnO nanorods,the hydrophobic nature of IL3 created the higher nanosize than the ZnO nanoparticles formed by other two ionic liquids.Antibacterial properties of the synthesized ZnO nanostructures were investigated against Staphylococcus aureus（gram positive） and Escherichia coli（gram negative） bacteria by Agar diffusion test method.Microbial experiments indicate that the synthesized ZnO samples show a wide spectrum of antimicrobial activities and performed better against S.aureus than E.coli with the same concentration of ZnO.