Purification of undiluted ionic liquids from trace-colored impurities for spectroscopy by octadecylsilyl solid-phase extraction

Ionic liquids are often contaminated by trace-colored impurities. In this paper, a solid-phase extraction (SPE) method for purification of undiluted imidazolium ionic liquids was described. A SPE apparatus with octadecylsilyl (ODS) solid phase was proposed to separate these impurities from ionic liquids via hydrophobic interaction. Solid-phase extraction with ODS can improve the spectroscopic quality obviously for the tested ionic liquids. Without introducing any solvent to ionic liquid, the purified ionic liquid can be used directly in spectroscopic measurements. It was found that short alkyl chain ionic liquids were purified more efficiently than the long alkyl chain ones. This method can be used to purify the hydrogen-bonding anion containing ionic liquids, which cannot be decolorized efficiently by conventional active charcoal method. In comparison with other existing purification methods, ODS is advantageous to solve the purification problem of ionic liquids.     

The Use of an Ionic Liquid in a Karr Reciprocating Plate Extraction Column: Dispersed Phase Hold-up Prediction

The use of ionic liquids (ILs) as alternatives to volatile organic liquids in solvent extraction is being considered in a number of applications. This study presents data on the dispersed phase holdup of the ionic liquid [bmim][PF₆] with water in a Karr extraction column. It was found that this system conforms to the standard slip velocity relationships and that the holdup can be predicted using existing correlations for dispersed phase holdup in Karr reciprocating plate columns. This indicates that the incorporation of ionic liquids into existing processing equipment is relatively straightforward and they behave in a predictable manner.     

Ionic liquid effects on mass transfer efficiency in extractive distillation of water–ethanol mixtures

The relatively high viscosities of ionic liquids could reduce the mass transfer efficiency of the extractive distillation process. The rate-based model was adopted to analyze this phenomenon since it predicted the performance of an extractive distillation pilot plant using ionic liquids as solvent. For the water–ethanol separation, three ionic liquids: 1-ethyl-3-methylimidazolium chloride, 1-ethyl-3-methylimidazolium acetate and 1-ethyl-3-methylimidazolium dicyanamide and the organic solvent ethylene glycol were used for the analysis. Simulations were conducted for sieve trays and Mellapak^® 250Y. The results indicate that relatively high viscosities affect the mass transfer efficiency. However, the improvements in relative volatilities obtained from the ionic liquids help to overcome this effect. However, with high solvent viscosities (>65 mPa s at T = 353.15 K) it was not possible to overcome the reductions. Additionally, at higher distillate rates high relative volatilities yielded negative effects on mass transfer efficiency because of a decrease in vapor velocity.     

Homogeneous Liquid–Liquid Extraction of Rare Earths with the Betaine—Betainium Bis(trifluoromethylsulfonyl)imide Ionic Liquid System

Several fundamental extraction parameters such as the kinetics and loading were studied for a new type of metal solvent extraction system with ionic liquids. The binary mixture of the ionic liquid betainium bis(trifluoromethylsulfonyl)imide and water shows thermomorphic behavior with an upper critical solution temperature (UCST), which can be used to avoid the slower mass transfer due to the generally higher viscosity of ionic liquids. A less viscous homogeneous phase and mixing on a molecular scale are obtained when the mixture is heated up above 55 °C. The influence of the temperature, the heating and cooling times, were studied for the extraction of neodymium(III) with betaine. A plausible and equal extraction mechanism is proposed in bis(trifluoromethylsulfonyl)imide, nitrate, and chloride media. After stripping of the metals from the ionic liquid phase, a higher recovery of the ionic liquid was obtained by salting-out of the ionic liquid fraction lost by dissolution in the aqueous phase. The change of the upper critical solution temperature by the addition of HCl or betaine was investigated. In addition, the viscosity was measured below and above the UCST as a function of the temperature.     

Investigation on Aggregate Formation of Ionic Liquids

Understanding the behavior of ionic liquids on the molecular level is essential for explaining solubilizing or reaction processes, including catalytic reactions in ionic liquids or with ionic liquids as co‐solvent. Using mass spectrometry techniques it is possible to characterize their aggregate formation behavior, which depends on the used solvent. With increasing polarity of the solvent and decreasing ionic liquid concentration, the size of the formed aggregates decreases. From conductivity measurement curves “critical aggregate concentrations” were calculated, which confirm the results of mass spectrometry measurements. Addition of ionic liquids increases the solubility of acetophenone in water. This effect can be explained by the aggregate formation ability of ionic liquids. The findings can be used to explain the outstanding solubility and solvation properties of ionic liquids.     

丁二烯抽提工艺中离子液体添加剂的筛选及分离性能

提出以离子液体为第三组分的丁二烯抽提新工艺,通过考察不同结构的离子液体对C₄组分在复合萃取剂中相对挥发度的影响,并结合量化计算的方法,研究了该工艺中萃取剂和第三组分与C₄组分的相互作用机理,从而优选出适用于该工艺的离子液体添加剂[Emim][PF₆]。另外研究了该离子液体在工业条件下对C₄组分分离性能的影响,并对改进前后的工艺进行全流程模拟计算。结果表明：与现有乙腈法相比,离子液体的加入有利于提高C₄在新型萃取剂中的相对挥发度,具有很好的分离效果。含离子液体的新工艺可使能耗降低约6.62%,乙腈消耗量降低约24%,而且离子液体能够回收利用,回收率高达98%（质量分数）以上,因此基于离子液体的乙腈法抽提丁二烯新技术具有很好的工业应用前景。     

离子液体萃取重金属离子的研究进展

离子液体作为一种新型的绿色溶剂,在重金属离子萃取分离方面较传统的有机溶剂有显著的优势。本文系统综述了近年来使用离子液体萃取重金属离子的研究进展,详细讨论了离子液体萃取重金属离子的原理和影响因素,包括螯合剂浓度、萃取时间、萃取温度、离子液体组成、溶液pH值、金属离子初始浓度、干扰离子以及水/离子液体质量比等。进一步介绍了提高离子液体萃取性能的措施以及金属离子的脱除与离子液体的回收状况,以及该萃取方法在废水处理、重金属离子分析和冶金中的研究与应用现状,最后指出其未来发展方向是合成功能化离子液体、提高萃取效率,以实现其工业化应用。     

离子液体在萃取脱硫研究中的应用进展

论述了离子液体应用于燃料油萃取脱硫的发展历程,通过对比萃取脱硫、萃取耦合化学氧化脱硫、萃取联合催化氧化脱硫三种不同体系的脱硫机理与技术优势,探究了离子液体的萃取性、催化性、氧化性及其再生问题。阐述了离子液体在燃料油脱硫领域的发展趋势。     

Selective Separation of Toluene/n‐Heptane by Supported Ionic Liquid Membranes with [Bmim][BF4]

Room‐temperature ionic liquids serve as alternative solvents for volatile organic compounds in liquid‐liquid extraction and liquid membrane separation. 1‐Butyl‐3‐methylimidazolium tetrafluoroborate ([Bmim][BF₄]) was applied for extraction and supported ionic liquid membranes (SILMs) to separate toluene and n‐heptane. A high separation factor of toluene was achieved due to the strong interaction between ionic liquid cations and toluene. The mass transfer performance of the SILM process was enhanced by higher operating temperature. With the increase of initial toluene concentration in the feed phase, the mass transfer flux and removal efficiency of the SILM process were improved, while the separation factor decreased. The mass transfer flux was growing with the increase of flow rate at both sides. The SILM process was stable over a long time period due to the high viscosity and low volatility of [Bmim][BF₄].     

离子液体萃取分离结构相似化合物研究进展

结构相似化合物的高效分离是化学工业最具挑战的难题之一,传统分离方法存在选择性低、溶剂消耗大、能耗高等不足。基于离子液体较强的氢键、π-π作用能力及良好的成相能力,离子液体液-液萃取过程能够有效识别结构相似化合物物化性质的微小差异,提高分离选择性,同时还可获得较高的分配系数和萃取容量,并抑制乳化的发生。本文在简要介绍离子液体偶极性/可极化性、氢键酸碱性和液-液相平衡规律的基础上,系统综述了离子液体液-液萃取技术在不同类型结构相似化合物选择性分离方面的研究进展,探讨了研究中存在的问题和未来发展方向。与亲水性化合物的分离相比,离子液体液-液萃取技术在疏水性结构相似化合物及表面活性结构相似化合物的分离中更具优势。离子液体-分子溶剂复合萃取剂的研究则为解决离子液体黏度大、成本高等问题提供了可行途径。     

微反应器耦合离子液体强化萃取过程的研究进展

离子液体作为一种绿色溶剂在强化萃取过程中获得了广泛的应用，但是高昂的生产成本以及以高黏度为特征的流体力学性质阻碍了其工业化应用。微化工技术为基于离子液体的连续化萃取提供了一种高效的过程强化平台。近年来，微化工技术与离子液体技术的耦合强化在萃取分离领域越来越受到关注。本文主要综述了微流动萃取技术的基本现状、离子液体参与的萃取过程特征、微反应器内涉及离子液体的互不相溶液-液两相流型、传质及其强化机制，重点介绍了微反应器在基于离子液体萃取金属、有机物等过程中的应用、微流动萃取过程放大的研究进展，并对涉及离子液体的多级萃取、功能化离子液体的萃取应用及其相应的微流动萃取放大等研究方向进行了展望。     

Separation of Ionic Liquid Dispersions in Centrifugal Solvent Extraction Contactors

Abstract

Separations of dispersions formed by mixing immiscible organic room‐temperature ionic liquids (IL)/hydrocarbon/and aqueous systems using a centrifugal solvent‐extraction contactor have been successfully demonstrated in proof‐of‐concept testing. This accomplishment is significant in that physical property factors that are typical of ionic liquid systems (e.g., similar densities of the bulk phases, low interfacial tensions, and high viscosities) are typically unfavorable for dispersion separation, particularly in continuous processes. Efficient separation of dispersions containing ionic liquid solvents is essential for utilization of these compounds in liquid‐liquid extraction applications to maximize both solute transfer efficiency and solvent recovery. Efficient solvent recovery is of particular concern in IL applications because of the high cost of most IL solvents.

This paper presents the results of initial experiments with three hydrophobic ionic liquids to determine how their physical properties affect phase mixing and phase disengagement in contact with an aqueous solution using a centrifugal contactor. While the results of the reported work are promising, additional work is needed to optimize existing mathematical models of contactor hydraulics to address special considerations involved in IL‐based processes and to optimize the equipment itself for IL applications.     

离子液体用于盐湖卤水萃取提锂的研究进展

从高镁锂比盐湖卤水中高效、清洁提锂对于保障中国锂工业绿色发展具有重要意义。溶剂萃取法盐湖提锂是盐湖提锂研究和应用中广泛使用的方法,但是存在环境污染大、设备腐蚀严重等问题。近年来,离子液体作为一种绿色高效的介质,已成为溶剂萃取法盐湖提锂研究的热点方向,并且已经取得了较大的研究进展。然而,离子液体萃取体系存在黏度大、离子液体流失、萃取机理不明确等问题。对离子液体用于盐湖萃取提锂的研究进展进行了综述,介绍了不同离子液体在萃取过程中用作萃取剂、协萃剂和稀释剂的研究现状。最后对离子液体用于盐湖提锂的研究前景做了展望,提出开发新型离子液体、建立和优化新型萃取工艺是未来发展方向。     

绿色离子液体的合成与应用

离子液体作为一种新型绿色溶剂,目前被广泛应用于有机合成、溶剂、萃取和分离、电化学等领域。本文主要介绍了离子液体的特点和几种合成方法。分析比较了不同合成方法的特点,介绍了离子液体作为溶剂的原理和应用。     

离子液体-磷酸三丁酯体系分离盐湖卤水镁锂

将一种典型的室温离子液体(ionic liquids, ILs)1-辛基-3-甲基咪唑六氟磷酸盐作为替代溶剂用于盐湖卤水萃取锂。在该萃取体系中, 离子液体和磷酸三丁酯(TBP)分别用作萃取介质和萃取剂。详细考察了水相酸度、相比等因素对锂分离效率的影响。初步结果表明:与传统萃取体系相比, 该离子液体萃取体系能极大提高萃取效率。该体系最优条件包括: TBP/ILs=9/1(体积比), 相比O/A=2:1, 水相的pH萃取前不需要调节。在此条件下, 锂和镁的单级萃取效率分别为80.64%和5.30%。经过三级逆流萃取, 锂的萃取率高达99.42%。在温度为80℃, 反萃相比A/O为2的条件下, 锂和镁的单级反萃效率分别为98.78%和99.15%。反萃水相中的镁锂比(Mg/Li)降至3.03, 与初始值相比降低了93.41%。     

复合离子液体组成对硫化氢的氧化脱硫性能的影响

针对纯铁基离子液体（Fe-IL）在脱硫过程中气液传质效率较低、铁活性不高等缺陷导致的脱硫液易被击穿、硫容小和再生缓慢等问题,以铁基离子液体（Fe-IL）为基质,选用锌基离子液体（Zn-IL）、锰基离子液体（Mn-IL）和1,3-二甲基咪唑啉酮（DMI）为助剂,调节相互之间的质量比配制复合离子液体基脱硫液,并试验上述混合溶液的脱硫效果。实验结果表明,复合金属离子液体之间具有协同强化脱硫的作用,1,3-二甲基咪唑啉酮对铁基离子液体脱硫有着较好的活化作用,其中铁锌基离子液体与1,3-二甲基咪唑啉酮组成的复合液脱硫效果更为理想。     

Microstructured reactors and supports for ionic liquids

Different types of microstructures and their applications with respect to the synthesis and the use of ionic liquids are presented. Microstructured reactors are suitable for reactions with fast intrinsic kinetics, requiring high mass and heat transfer performances. Chemical synthesis can be performed safely under operating condition (e.g. high temperature, pressure, etc.) difficult to obtain in traditional reactors. The examples presented clearly indicate that microstructured reactors offer superior performance for the synthesis of ionic liquids in comparison to conventional equipment. For the use of ionic liquids as reaction media, existing ionic liquids show some limitations due to their higher viscosity compared to conventional solvents. Therefore, future research should be focused on the development of low viscosity ionic liquids.The approaches to use ionic liquids in microstructured reactors and in combination with microstructured supports for catalytic reactions show many advantages in view of high product selectivity and yield. The use of supported ionic liquids on microstructured materials seems to be particularly promising for gas phase as well as for gas/liquid reactions.     

Temperature-Assisted Removal of Triphenylmethane Dyes from Water with Novel Hydrophobic Benzothiazolium Ionic Liquids

In this work, a simple and effective extraction method for triphenylmethane dyes from their aqueous solution was developed. Three novel task-specific ionic liquids based on N-alkylbenzothiazolium cations were prepared and their extraction performance in this new method was evaluated in self-prepared and real water samples. Through the control of temperature, the ionic liquids could be dispersed into the aqueous solution, first, to fully contact with the dyes and then easily recovered as tiny particles enriching these target compounds. Parameters of the extraction conditions including the amount of the ionic liquid, volume of the dispersing solvent, dissolving temperature, extraction time, pH value, and ionic strength have been investigated. The results showed that the major driven forces for the extraction were hydrogen bonding and hydrophobic interactions between the ionic liquids and the dyes. The proposed method combined the advantages of both homogeneous mixing and heterogeneous solid-liquid separation in extraction process, which was expected to lay the foundation for actual application in future.     

离子液体回收的研究进展

离子液体作为一种绿色溶剂可以有效地解决目前存在的能源和环境问题。由于离子液体相对于其它有机溶剂具较好的化学稳定性,使其在众多的研究领域受到越来越多的关注。但是离子液体存在着合成成本较高、回收难度较大等技术瓶颈问题,因而阻碍了它的广泛应用。而安全、有效地回收离子液体能够解决这一难点。离子液体的回收方法有减压蒸馏、膜分离、盐析、液液萃取等。离子液体的有效回收可以促进化学合成、纤维素提取等领域的快速发展。     

近十年来离子液体在萃取金属方面的研究进展

离子液体具有不挥发、稳定性好、结构可调、无毒、对环境友好等特点,被认为是一种可替代传统溶剂的新型绿色溶剂,在电化学、分析化学、有机合成及催化反应等领域都有广泛的应用.主要根据离子液体在萃取分离中的应用研究,将近十年来离子液体对于如重金属、碱金属和碱土金属、稀土金属、稀有金属及放射性金属等各种金属离子的萃取效果进行了综述.