离子液体在萃取和液膜过程中的应用研究新进展

介绍了近几年离子液体在萃取和液膜分离过程中研究应用的新进展,并展望了离子液体在分离科学应用的前景和发展方向。引用文献56篇。     

分散液液微萃取–高效液相色谱法测定尿液中的阿替洛尔

建立基于离子液体–分散液液微萃取–高效液相色谱法检测尿液中阿替洛尔的新型分析方法.将环境友好的萃取剂离子液体和分散剂乙腈的混合溶液快速注入样品中,瞬间完成高效的萃取过程.在低温条件下,将下层的离子液体固化,实现萃取剂高效地收集,用高效液相色谱–二极管阵列检测器进行定量分析.阿替洛尔的质量浓度在0.01～1μg/mL范围...     

PVC固载离子液体选择性分离碱性蛋白的研究

近年来,离子液体被广泛应用于生物大分子的萃取分离~([1]).对于液液萃取(包括离子液体微乳和双水相萃取),离子液体消耗量比较大,而且离子液体黏度较大造成其定量操作十分困难,因此离子液体的固载化越来越受到人们重视.     

微流控液液萃取-液液波导集成化分析系统

利用溴化1-丁基-3-甲基咪唑离子液体/碳酸钠溶液双水相体系,实现了多相层流液液萃取.以具有较高折射率的离子液体为液芯,较低折射率的盐溶液为包层,实现了液液波导吸光度检测.据此建立了一种液液萃取与液液波导检测集成化的微流控分析系统.该系统对甲酚红试样的萃取率在93%以上,对甲酚红试样检测的线性范围为0.01~0.40 mg/m L,相对标准偏差为3.4%(n=11),检出限为3.8μg/m L(3σ).该系统将萃取分离与液液波导长光程吸光度检测集成在一起,为拓展吸光度检测在微流控系统中的应用提供了新思路.     

离子液体在蛋白质萃取分离中的应用

离子液体具有独特的物化性质如热稳定性好、不挥发、不易燃和良好的生物兼容性,近年来作为传统有机溶剂的替代物在有机合成、电化学、催化和萃取分离等领域得到了广泛应用。本文简要综述了以离子液体为媒介的萃取体系在蛋白质分离富集和分析中的相关研究和应用进展,包括辅助萃取体系、直接萃取体系、双水相萃取体系、微乳萃取体系、结晶体系和基于离子液体的固相萃取体系等。     

室温离子液体在分离科学研究中的新进展

室温离子液体作为一种重要的绿色溶剂,由于在金属离子、小分子有机物的萃取分离,气体吸附分离以及作为液相和气相色谱固定相等许多分离过程中体现出高分离效率和高选择性的特点,正在成为分离科学研究的前沿领域.着重总结了从2003—2006年的室温离子液体在分离科学领域中的新进展,并对其应用领域和发展前景做了展望.提出进一步加强离子液体的功能化和固定化技术及其在分离科学中的应用基础研究,探索离子液体有效的回收和再循环利用的新方法,是离子液体今后在分离科学研究中的一系列重要内容.     

离子液体液-液萃取-高效液相色谱测定水中酚类化合物

建立了离子液体1-丁基-3-甲基咪唑六氟磷酸盐([C4mim][PF6])液-液萃取-高效液相色谱测定水中酚类化合物的方法.研究了水相pH值、萃取时间、水相体积及盐的浓度对萃取的影响.最佳萃取条件分别为:水相pH值为5,萃取时间为40 min,水相体积为60 mL.对比了离子液体对1-辛醇对苯酚、4-硝基苯酚、2-硝基苯酚、2,4-二甲基苯酚和双酚A的富集效率.在最佳条件下,离子液体对5种酚的富集倍率在9～151之间,方法对苯酚、4-硝基苯酚、2-硝基苯酚、2,4-二甲基苯酚和双酚A的检出限分别为:2.0、0.9、0.3、1.8和1.1 μg/L.将该方法应用于自来水、河水、湖水和污水的检测,回收率为87.9%～109.9%.     

离子液体萃取分离铀(Ⅵ)的研究进展

本文对近十余年来离子液体萃取分离U(Ⅵ)的研究进展进行了综述,主要从离子液体为萃取稀释剂及目标专一性离子液体为萃取剂兼稀释剂两个方面进行总结。     

咪唑离子液体及其萃取体系的辐射效应研究

离子液体因其低挥发性,高热稳定性及在萃取金属离子方面的优良表现被认为是乏燃料后处理中萃取分离放射性核素的新一代绿色溶剂。但从乏燃料后处理强辐射的应用环境来看,需要首先对离子液体及其萃取体系的辐射效应进行系统研究和评估。本文以两种常见的憎水性咪唑离子液体1-丁基-3-甲基咪唑六氟磷酸盐( )和1-丁基-3-甲基咪唑三氟甲基磺酰亚胺酸盐( )为例,综述了我们在离子液体及其萃取体系的γ辐射效应方面的最新研究进展,内容包括纯离子液体在氮气气氛下的辐射效应,硝酸对离子液体辐射效应的影响,离子液体辐解产物的分离分析及γ辐照对离子液体体系萃取金属离子的影响等。基于以上研究对离子液体用于乏燃料后处理的可行性进行了评估,同时对离子液体及其萃取体系的辐射效应研究进行了展望。     

分散液液微萃取技术的研究进展

分散液液微萃取是一种基于传统液液萃取的新型样品前处理技术。该文以分散液液微萃取技术中萃取剂的筛选为出发点,综述了低密度萃取剂、辅助萃取剂、反萃取剂和离子液体等低毒性萃取剂在该技术中的应用,以及应用自制装置、溶剂去乳化、悬浮萃取剂固化,辅助萃取,反萃取和离子液体-分散液液微萃取等萃取模式;并简要评述了该技术与液液萃取、固相萃取、固相微萃取、分散固相萃取、基质固相分散萃取、超临界流体萃取、超声辅助萃取等其他样品前处理技术的联用特性。     

Ionic liquids based on N-vinyl-gamma-butyrolactam: potential liquid electrolytes and green solvents

The first examples of room temperature ionic liquids, containing N-alkyl-N-vinyl-2-pyrrolidinonium (N-alkyl-N-vinyl-gamma-butyrolactam) cations in combination with bromide and tetrafluoroborate anions, have been synthesized and the spectroscopic and physical characteristics of this family of ionic liquids have been investigated for intended use as liquid electrolytes and green solvents.     

室温离子液体催化合成碳酸丙烯酯

碳酸丙烯酯(PC)是一种性能优良的高沸点高极性有机溶剂,在有机合成、化妆品、气体分离、电池介电质[1]及金属萃取[2]等领域得到广泛的应用. 近年来,许多尿素生产厂家将其用作脱碳剂,使其需求量大增. PC合成方法主要有光气法、酯交换法、氯丙醇法及环氧丙烷(PO)与CO2环加成等. 其中, 以PO与CO2为原料环加成制PC是一条低污染、环境友好的路线. 已报道的用于PO与CO2环加成的催化剂有碱、季铵盐、金属盐[3]、配合物[4～6]以及MgO[7], MgO-Al2O3[8], KI/ZnO[9],KI/冠醚和KI/聚乙二醇[10]等. 尽管品种繁多,但仍存在催化剂活性不高,产物分离及催化剂回收困难等问题.     

Novel ascorbic acid based ionic liquids for the in situ synthesis of quasi-spherical and anisotropic gold nanostructures in aqueous medium

A series of newly designed ascorbic acid based room temperature ionic liquids were successfully used to prepare quasi-spherical and anisotropic gold nanostructures in an aqueous medium at ambient temperature. The synthesis of these room temperature ionic liquids involves, first, the preparation of a 1-alkyl (such as methyl, ethyl, butyl, hexyl, octyl, and decyl) derivative of 3-methylimidazolium hydroxide followed by the neutralization of the derivatised product with ascorbic acid. These ionic liquids show significantly better thermal stability and their glass transition temperature (Tg) decreases with increasing alkyl chain length. The ascorbate counter anion of these ionic liquids acts as a reducing agent for HAuCl4 to produce metallic gold and the alkylated imidazolium counter cation acts as a capping/shape-directing agent. It has been found that the nature of the ionic liquids and the mole ratio of ionic liquid to HAuCl4 has a significant effect on the morphology of the formed gold nanostructures. If an equimolar mixture of ionic liquid and HAuCl4 is used, predominantly anisotropic gold nanostructures are formed and by varying the alkyl chain length attached to imidazolium cation of the ionic liquids, various particle morphologies can formed, such as quasispherical, raspberry-like, flakes or dendritic. A probable formation mechanism for such anisotropic gold nanostructures has been proposed, which is based on the results of some control experiments.     

Bicyclic imidazolium-based ionic liquids: synthesis and characterization

We previously reported the use of imidazole as starting compound for preparing a bicyclic imidazolium ionic liquid, [b-3C-im][NTf₂], with an overall 29% isolated yield in four synthetic steps. This new room temperature ionic liquid was shown to be far more chemically stable than commonly used [bmim][PF₆], [bdmim][PF₆], and [bdmim][NTf₂]. Because of this intriguing chemical stability, it prompted us to develop a more generalized and high yielding synthesis so that molecular diversity of bicyclic ionic liquids may be explored. In this work, we amended the previous synthetic route by employing 4-chlorobutyronitrile or 5-chlorovaleronitrile as starting materials and successfully developed a five-step synthesis of a series of novel bicyclic imidazolium-based ionic liquids in 40-53% overall isolated yields. We investigated intrinsic reactivity of all bicyclic ionic liquids prepared and found that, under strongly basic conditions, among all tested ionic liquids the 5,5-membered [R-3C-im][NTf₂] ionic liquids were most stable to solvent deuterium isotope exchange while the previously reported [bdmim][NTf₂] ionic liquid was 50% deuterium exchanged at its C-2 methyl in 30 min at ambient temperature. Under identical condition, the commonly used [bmim][NTf₂] ionic liquid was deuterium exchanged instantaneously at its C-2 hydrogen. In the absence of bases, only [bmim][PF₆] was deuterium exchanged (50% within 1 h) and all other ionic liquids gave no detectable exchanges even after 25 days at ambient temperature. Moreover, both [bmim][NTf₂] and [bdmim][NTf₂] ionic liquids were readily methylated at C-2 position with methyl iodide under basic condition at room temperature. Under the same condition, [R-3C-im][NTf₂] and [R-4C-im][NTf₂] ionic liquids were completely stable and chemically inert. We envisioned that [R-3C-im][NTf₂] should be well suited as solvents for organic synthesis.     

Anionic rare-earth thiocyanate complexes as building blocks for low-melting metal-containing ionic liquids

The first examples of ionic liquids with rare-earth-containing anions are presented. These ionic liquids based on rare-earth thiocyanate complexes are liquid at room temperature, despite the multivalent character of the anionic building blocks.     

Room temperature ionic liquids: new solvents for Schrock's catalyst and removal using polydimethylsiloxane membranes

A room temperature ionic liquid was used as the solvent for metathesis reactions with the Schrock catalyst and a new method to facilitate separation between small molecules and ionic liquids using polydimethylsiloxane thimbles is reported.     

Immiscible electrolyte systems based on asymmetric hydrophobic room temperature ionic liquids

The effect on the melting point of the introduction of asymmetry in tetraalkylammonium halide salts has been investigated leading to the synthesis of new, hydrophobic (room temperature) ionic liquids suitable for liquid/liquid electrochemistry; one of these, tri(hexyl)decylammonium tetrakis(pentafluorophenyl)borate, displays the largest electrochemical window observed to date for a biphasic room temperature ionic liquid system.     

Synthesis and characterization of new pyrrolidinium based protic ionic liquids. Good and superionic liquids

New pyrrolidinium-cation-based protic acid ionic liquids (PILs) were prepared through a simple and atom-economic neutralization reactions between pyrrolidine and Br?nsted acids, HX, where X is NO 3 (-), HSO 4 (-), HCOO (-), CH 3COO (-) or CF 3COO (-) and CH 3(CH 2) 6COO (-). The thermal properties, densities, electrochemical windows, temperature dependency of dynamic viscosity and ionic conductivity were measured for these PILs. All protonated pyrrolidinium salts studied here were liquid at room temperature and possess a high ionic conductivity (up to 56 mS cm (-1)) at room temperature. Pyrrolidinium based PILs have a relatively low cost, a low toxicity and exhibit a large electrochemical window as compared to other protic ionic liquids (up 3 V). Obtained results allow us to classify them according to a classical Walden diagram and to determinate their "Fragility". Pyrrolidinium based PILs are good or superionic liquids and shows extremely fragility. They have wide applicable perspectives for fuel cell devices, thermal transfer fluids, and acid-catalyzed reaction media as replacements of conventional inorganic acids.     

Physical and Excess Properties for Binary Mixtures of 1-Methyl-3-Octylimidazolium Tetrafluoroborate, [Omim][BF4], Ionic Liquid with Different Alcohols

In recent years, ionic liquids have increasingly gained importance as green solvents. The potential of these organic salts, which are moisture and air stable at room temperature, for new chemical processes and technologies is beginning to be recognized. Research on the thermophysical properties of ionic liquids and their mixtures form the basis for future applications. In this contribution, densities, refractive indices, speeds of sound and dynamic viscosities of 1-methyl-3-octylimidazolium tetrafluoroborate, [Omim][BF₄], the room temperature ionic liquid (IL) in binary mixtures with methanol, ethanol, 1-propanol and 2-propanol were measured at 298.15K and atmospheric pressure. The excess molar volumes and molar refraction, isentropic compressibility and dynamic viscosity changes of mixing have been calculated and were satisfactorily correlated by the Redlich–Kister polynomial.     

Raman spectroscopic study on solvation of diphenylcyclopropenone and phenol blue in room temperature ionic liquids

We investigated the solvation of several room temperature ionic liquids by Raman spectroscopy using diphenylcyclopropenone (DPCP) and phenol blue (PB) as probe molecules. We estimated acceptor numbers (AN) of room temperature ionic liquids by an empirical equation associated with the Raman band of DPCP assigned as a C=C stretching mode involving a significant C=O stretching character. According to the dependence of AN on cation and anion species, the Lewis acidity of ionic liquids is considered to come mainly from the cation charge. The frequencies and bandwidths of the C=O and C=N stretching modes of phenol blue are found to be close to those in conventional polar solvents such as methanol and dimethyl sulfoxide. The frequencies of these vibrational modes show similar dependence upon the electronic absorption band center as is observed in conventional liquid solvents. However, peculiar behavior was found in the Raman bandwidths and the excitation wavelength dependence of the C=N stretching mode in room temperature ionic liquids. Both the bandwidth of the C=N stretching mode and the extent of the excitation wavelength dependence of the Raman shift of the C=N stretching mode tend to decrease as the absorption band center decreases, in contrast to the case of conventional solvents. This anomaly is discussed in terms of the properties of room temperature ionic liquids.