离子液体萃取有机物的研究进展

离子液体具有结构可调控、不挥发以及对目标物具有一定选择性等特点,因而近来在萃取领域的应用日益受到关注,被认为是一种可替代传统溶剂的新型绿色溶剂。本文从液-液萃取、固相萃取、液相微萃取、固相微萃取、超声萃取、微波萃取6个方面综述了离子液体在萃取有机物中的应用。     

离子液体在萃取有机物方面的应用

近些年来,世界各国学者对离子液体的研究越来越多,随着对离子液体研究的深入,离子液体的应用逐渐渗透到各个领域中。主要介绍近年来离子液体在萃取有机物方面的应用进展。     

CO2/离子液体混合物相平衡的研究进展

离子液体对二氧化碳有良好的溶解性能,可以实现二氧化碳的固定与转化。超临界二氧化碳可以从离子液体/有机物体系中选择性萃取有机物,避免相间的交叉污染,实现离子液体的回收。从CO2在离子液体中的溶解度实验测定方法、CO2/离子液体二元体系高压相平衡测定、SC-CO2/离子液体/有机物的三元体系相平衡研究以及模型预测四个方面介绍了CO2/离子液体体系相平衡研究的最近进展,分析了这一研究领域的发展方向。     

含离子液体体系液液相平衡的计算

含有离子液体体系的液液平衡数据是离子液体实际应用最重要的基础数据之一。文中在扩展的NRTL方程中进一步引入了分子体积修正项,计算结果表明,该修正能更好地提高模型预测含离子液体体系的精度。因此,文中利用该模型关联了文献报道的多种常见离子液体和醇类二元体系,所有体系计算值与实验值的质量分数最大绝对误差小于3.5%,平均绝对误差小于1.5%;同时,文中利用拟合得到的二元模型参数,成功预测了23℃和50℃时水-正丁醇-[bmim]PF6三元体系的液液平衡相图。     

离子液体-水体系的相平衡

通过对1-丁基-3-甲基咪唑四氟硼酸盐([bmim][PF4])离子液体 水体系相平衡及NaCl、NaBF4和氯化1-丁基-3-甲基咪唑([bmim]Cl)对离子液体 水体系相平衡的影响进行了研究,结果表明: 离子液体[bmim][BF4] H2O二元体系具有典型的最高上临界溶解温度(UCST)行为,其最高上临界温度为5.3℃左右,临界组成为50%(水的质量分数); NaCl和NaBF4降低 [bmim][BF4] H2O体系的混溶性,而[bmim]Cl增加该体系的混溶性.由此得到一种简单定性地判断离子液体[bmim][BF4]中可能存在的杂质种类和水平的方法,并利用此结果可设计纯化该离子液体的绿色工艺.     

含离子液体苯-正丙醇体系等压气液相平衡

选择癸基咪唑醋酸盐([DMIM] [OAc])离子液体作为萃取精馏分离苯-正丙醇共沸体系的萃取剂.在101.3 kPa下测定了苯-正丙醇-癸基咪唑醋酸盐三元体系的等压气液相平衡数据,使用非随机双液体模型(NRTL模型)对所得数据进行了关联,得到了模型参数.实验结果表明:[DMIM][OAc]的加入对体系中的苯产生了显著...     

含离子液体苯-甲醇物系等压气液相平衡

在常压下测定了苯+甲醇+三辛基甲基醋酸铵([N1,8,8,8][OAc])三元物系的等压气液相平衡数据.实验结果表明:[N1,8,8,8][OAc]的加入可以显著提高苯对甲醇的相对挥发度,当[N1,8,8,8][OAc]的摩尔分数为0.08时共沸现象完全消失.分别采用Wilson和NRTL热力学模型对该气液相平衡数据进...     

反相高效液相色谱法直接测定离子液体中咪唑杂质含量

研究了高效液相色谱法测定离子液体中的杂质(4-甲基咪唑)含量的测定方法。在不同色谱条件下,分离效果不同。在AllsphereODSC18色谱柱上,以水-甲醇为流动相,两者流速比为水∶甲醇=1∶9,流速为1.0mL/min,在215nm处进行紫外检测,离子液体能与4-甲基咪唑很好的分离。另外,在HypersilBDSC18色谱柱上用类似的条件分离效果也较好。采用该法的线性范围,检出限分析考察,结果表明,其灵敏度高、定量准确、重现性好,适合于离子液体中4-甲基咪唑这种杂质含量的测定。     

非极性有机物蒸发热与正常沸点的关联

通过对正烷烃蒸发热、正常沸点与碳数关系的研究,理论推导出蒸发热与正常沸点之间的关系,并拟合得一简单适用的公式:Hυ=23.234×BP1.21256+1502.13。应用于上百种常见非极性有机物,误差较小。     

应用于离子液体体系汽液平衡测定的液相配制、气相分析方法

面向离子液体应用于萃取精馏,讨论了离子液体体系汽液平衡测定的液相配制、气相分析方法,提出了改进的气相回流器和沸腾器结构。基本思路来源于韩世钧先生研究团队发展的汽液平衡测定的拟静态法和置换法,以及能够主动提供气化中心的沸腾器结构。提出了液相组成计算方法和误差估计,适用于含多个挥发性组分和多个非挥发性组分体系的任意组分。上述方法能够实测获得挥发性组分的活度系数,并避免较为繁琐的含离子液体液相的分析。通过连续配制测定,能够获得活度系数随组成的变化规律,并应用于萃取精馏溶剂性能的评价及筛选。     

离子液体萃取分离有机物研究进展

离子液体是一种结构可调的绿色溶剂,在催化、分离和电化学等领域具有广泛应用,特别是在有机物萃取分离方面,由于其低挥发性及功能可调,避免了传统有机溶剂可能导致的VOCs二次污染,有望成为绿色高效的新型萃取剂。本文系统地综述了离子液体在萃取分离烃类化合物、有机酸、醇类、酚类以及天然产物中的应用研究进展,详细论述了离子液体萃取分离有机物的萃取机理和影响因素,离子液体与溶质分子之间强的氢键、π-π、范德华力以及静电作用使其具有良好的萃取分离能力,表明离子液体是一类可替代有机溶剂实现高效萃取分离有机化合物的潜在溶剂。针对实际工作应用,还需解决其高黏度、高成本等问题,此外萃取后离子液体的回收仍是其大规模应用而需要亟待解决的难题。     

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。     

Extraction of polycyclic aromatic hydrocarbons from fluid catalytic cracking diesel with ionic liquids

Ionic liquids (ILs) as promising green solvents were first proposed to extract polycyclic aromatic hydrocarbons (PAHs) from fluid catalytic cracking (FCC) diesel. The COSMO-RS model was used for preliminary screening of IL extractants. The liquid–liquid equilibrium (LLE) experiments were performed to show that the IL [BMIM][BF₄] has a high selectivity for the model oil system. Further, the LLE experimental results show that the solubility of 1-methylnaphthalene in [BMIM][BF₄] is relatively low, while the IL exhibits a high selectivity of n-hexadecane to 1-methylnaphthalene. This means that the use of [BMIM][BF₄] can obtain the high-purity products when considering the almost nonvolatility of IL. Compared to the benchmark process, the multistage countercurrent–reflux extraction process can improve the PAHs purity by about 2% at the expense of 5.06% total annual cost and 6.42% energy consumption, rendering the use of IL to extract PAHs from FCC diesel more feasible in industry.     

Protic and aprotic anionic oligomeric ionic liquids

We report on synthesis of linear and hyperbranched protic and aprotic anionic oligomeric ionic liquids (OILs). α,ω-Dicarboxy- and α,ω-disulfooligo(ethylene oxide)s, α-carboxy- and α-sulfooligo(ethylene oxide monomethyl ether)s, and di[(α-carboxyoligo(ethylene oxide monomethyl ether)] were synthesized using reaction of oligo(ethylene oxide diol) (MW 1000) and its monomethyl ether (MW 750) with phthalic-, 2-sulfobenzoic anhydride and pyromellitic dianhydride. Di- and mono-substituted anionic OILs were prepared by neutralizing these compounds with N-methylimidazole. Aprotic anionic OILs were synthesized by reaction of sodium salts of the prepared oligomeric di- and monoacids with 1,3-dimethyl imidazolium iodide. Hyperbranched protic and aprotic anionic OILs were prepared in a similar manner. The structure, thermal stability and ionic conductivity of the synthesized compounds in the range of 20–120 °C in anhydrous conditions is governed by the molecular architecture of the oligomeric chains and the type of the cation/anion moieties. OILs under study are amorphous at room temperature but some protic and aprotic linear-chain OILs prone to form a low melting temperature crystalline phase. The ionic conductivity of the synthesized OILs can be varied in broad range reaching 10⁻³ S/cm value at temperatures over 100 °C under anhydrous conditions.     

高压静电场对海水蒸发和沸点的影响

研究了不同条件下高压静电场对海水蒸发速率和沸点的影响。实验结果表明:高压静电场下海水蒸发的速率是常态下的1.5~2.1倍;海水沸点随高压静电场强度的增大而降低。由实验现象和数据分析得出:水分子是极性分子,在高压静电场下易形成电偶极矩,电偶极矩使水分子之间的氢键断裂,从而水分更易蒸发;氢键断裂的能量来源于海水的内能,而不是电场能转化而来的能量。     

调整高沸塔操作参数优化氯乙烯生产过程

通过适度降低氯乙烯高沸塔的操作压力及温度,提高氯乙烯与高沸物的分离度,进一步降低和稳定了氯乙烯单体中高沸物的含量,减少了水及其中的杂质含量。通过调整,提高了单体质量,减少了高沸塔内氯乙烯自聚和塔釜再沸器列管结焦情况,延长了设备的使用寿命,优化了氯乙烯的生产过程。     

脂肪族含氧有机物沸点的定量构效关系

引言沸点是化合物最基本的物理性质之一,也可以用来预测和估算化合物的其他物理化学性质,如临界性质、闪点等。沸点与分子结构和分子间作用力密切相关,实验测定是获得沸点最直接的方法,但     

Synthesis and application of dicationic ionic liquids

Ionic liquids were synthesised that consisted of two methylimidazolium rings joined by a spacer 1–12 carbon atoms in length. The bis(triflic)imides with spacer ≤C₄ were solids; the others were liquid at room temperature. The polarity of the dication liquids and their performance in the extraction of phenol from water were compared with those of similar monocationic liquids. Copyright © 2005 Society of Chemical Industry     

Predictive molecular thermodynamic models for ionic liquids

Predictive molecular thermodynamic models can bridge the gap between the microscopic molecular level and macroscopic system scale. Over the past few decades, ionic liquids (ILs), as a class of green solvents and functional materials, have received widespread research interest in the field of chemical processing owing to their unique physicochemical merits. This review aims to provide an easy-to-read and exhaustive reference regarding state-of-the-art predictive thermodynamic models for ILs, with more focuses on UNIFAC- and COSMO-based models and various applications involving phase equilibrium prediction, guidance for IL screening and design, and building equilibrium stage models for separation processes. This review provides a theoretical perspective on the structure–property relationships between molecular structures and phase behaviors for the systems and the constituted components covering a multi-scale viewpoint from molecular level to industrial scale. Moreover, the predictive capacities of different thermodynamic models are comprehensively compared.