离子液体在低碳烯烃/烷烃分离中的应用研究进展

低碳烯烃/烷烃的高效分离是石油化工领域可持续发展的关键过程之一,传统的低温精馏过程选择性低、能耗大。离子液体作为一种结构可调的绿色溶剂为低碳烃的高效分离提供了新的思路。本文综述了近年来国内外离子液体在低碳烯烃/烷烃分离中的研究进展,总结了常规离子液体、功能化离子液体以及含过渡金属的离子液体在低碳烯烃/烷烃分离中的应用,阐明了离子液体中阴阳离子、功能化基团、过渡金属与低碳烯烃相互作用的机理,着重介绍了合成金属功能化离子液体、添加金属盐、添加金属纳米粒子3种向离子液体中引入过渡金属方式的特点以及过渡金属的种类、比例,有机配体的类型对离子液体烯烃/烷烃分离性能的影响,并探讨了该方向的研究和发展趋势。     

萃取精馏中离子液体萃取剂的研究进展

离子液体的低熔点和不挥发等特点使其较传统的萃取精馏萃取剂具有先天的优势,具有广泛的应用前景。本文介绍了离子液体作为萃取精馏萃取剂的研究进展,综述了汽液平衡法、无限稀释活度系数法等筛选离子液体萃取剂方法的研究成果以及目前用于计算含离子液体体系的相平衡模型研究进展,分析了离子液体萃取剂用于实用仍存在的问题,并展望了今后的研究方向。     

用于芳烃/烷烃体系蒸汽渗透分离的离子液体支撑液膜研究

研究离子液体"填充型"支撑液膜制备规律,以及操作条件对苯/环己烷混合物蒸汽渗透分离过程影响。利用[C4mim][BF4]、[C8mim][BF4]、[C4mim][PF6]、[C6mim][PF6]、[4-Mebupy][BF4]、[3-Mebupy][BF4]离子液体分别制备支撑液膜,用于苯/环己烷混合物蒸汽渗透膜分离过程研究。实验比较了离子液体的种类、操作温度、原料液浓度等因素对苯/环己烷混合体系的蒸汽渗透膜分离性能的影响,其中[3-Mebupy][BF4]制得的支撑液膜对等体积配比的苯和环己烷混合物分离效果最佳,30℃时渗透通量为11.4g?m2?h?1,分离因子可达32.85。通过长时间运行的稳定性实验,证实离子液体支撑液膜的蒸汽渗透过程能够实现苯和环己烷的有效分离,具备良好的稳定性。离子液体"填充型"支撑液膜有望成为降低芳烃/烷烃等有机溶剂体系分离过程能耗的有效途径。     

基于COSMO-RS方法筛选离子液体用于焦油脱除

焦油的脱除是生物质气化规模化应用的难题。离子液体具有饱和蒸气压低、分子结构可设计等优势,在催化和吸收领域有广泛的应用前景,但在脱除焦油方面鲜有探索。以改进的COSMO-RS方法为基础,借助COSMOtherm软件推算离子液体对苯、甲苯、苯酚和萘等焦油模拟物的无限稀释活度系数。并进一步通过偏摩尔过量焓验证以上筛选结果。结果表明,优选的两取代基咪唑类离子液体对四种焦油模拟物的无限稀释活度系数值主要分布在0.4~1之间,预计具有良好的吸收性能。当阴离子相同时,两取代基咪唑阳离子随着R₁位置烷基侧链的增长吸收性能变好,其中[C₈MIM][NTf₂]表现出了较佳性能,吸收苯、甲苯和萘的γ^∞分别为0.95、1.24和1.36,但此时离子液体黏度较大;对于苯酚体系,[BF₄]^-阴离子性能较佳。     

离子液体分离体系的研究与发展

离子液体分离技术主要用于水中微量、痕量组分的分离与富集,也可用于水中有机污染物的去除,在许多方面优于传统的分离技术。离子液体分离技术的研究主要分为两个方向:离子液体双水相萃取技术和离子液体气浮溶剂浮选技术。综述了这两种技术的装置、影响因素、机理及应用,并指出了这两种技术的复合——离子液体双水相气浮溶剂浮选技术是今后的发展方向。     

基于COSMO-SAC模型的离子液体萃取剂的选择

COSMO-SAC模型是计算无限稀释活度因子的一种有效方法,只需知道分子结构,即可进行有机物或离子液体的无限稀释活度因子计算。COSMO-SAC模型中最耗时的计算步骤是产生σ-图谱(σ-profile)的量子化学计算。利用Materials Studio软件中的DMol3模块,建立了包含32种离子液体阴离子和191种离子液体阳离子的σ-图谱数据库。利用σ-图谱数据库和COSMO-SAC模型,针对离子液体液液萃取过程,提出了离子液体萃取剂的计算机辅助分子设计方法。以乙醇-乙酸乙酯体系为研究对象,选择了适宜的离子液体萃取剂,采用乙醇-乙酸乙酯-离子液体三元体系的液液平衡文献数据进行了验证。     

离子液体支撑液膜用于分离混合芳烃的研究

利用不同离子液体制备离子液体充填型支撑液膜,将其用于混合芳烃中对二甲苯的蒸汽渗透膜分离实验,比较了不同离子液体、不同支撑底膜、原料中对二甲苯的含量、操作温度等因素对分离性能的影响。结果表明,在40℃温度下,[Bmim][BF4]填充PVDF膜形成的支撑液膜对对二甲苯体积分数为60%的混合芳烃渗透通量为59.5 g/(m2·h),分离因子达16.5;经过90 h的实验测定,支撑液膜分离性能稳定。离子液体支撑液膜的蒸汽渗透过程能够实现从混合芳烃中将对二甲苯分离。     

离子液体支撑液膜用于分离混合芳烃的研究

利用不同离子液体制备离子液体"充填型"支撑液膜,将其用于混合芳烃中对二甲苯的蒸汽渗透膜分离实验,比较了不同离子液体、不同支撑底膜、原料中对二甲苯的含量、操作温度等因素对分离性能的影响。结果表明,在40℃温度下,[Bmim][BF4]填充PVDF膜形成的支撑液膜对对二甲苯体积分数为60%的混合芳烃渗透通量为59.5 g/(m2·h),分离因子达16.5;经过90 h的实验测定,支撑液膜分离性能稳定。离子液体支撑液膜的蒸汽渗透过程能够实现从混合芳烃中将对二甲苯分离。     

小分子烷烃与烯烃在离子液体中的溶解性能

研究了多种离子液体对小分子烃类的溶解性能,发现含有Cu(Ⅰ)的离子液体对烃类具有较高的溶解度和烯烃/烷烃溶解选择性,优选出了Et3NHCl-2.1CuCl离子液体。考察了温度和压力对小分子烃类溶解性能的影响规律,发现低温和高压有利烃类的溶解,烯烃/烷烃溶解选择性随温度和压力的升高而减小;在30℃和0.2 MPa的条件下,烯烃/烷烃溶解选择性均在8.3以上。烃类在离子液体中的初始溶解速率较大,但随时间的延长快速降低,相同条件下烯烃的溶解速率高于烷烃的溶解速率。烯烃/烷烃分离选择性随混合气中烯烃含量的减小而增大。升温可以解吸出离子液体中的烃类,烷烃比烯烃容易解吸,优化条件下的解吸率可达92%以上。离子液体对小分子烷烃和烯烃的吸收分离具有良好的重复使用性能。利用Gaussian 09软件对离子液体的阴离子与烯烃、烷烃的作用进行了计算分析,解释了烯烃和烷烃在不同离子液体中溶解性能差异的原因。     

离子液体分离富集镉离子的研究进展

离子液体是一种对环境友好的绿色溶剂,在重金属离子分离富集方面较传统有机溶剂有明显的优势。文章介绍了离子液体的基本概念和特点,详细阐述了离子液体分离富集镉离子的影响因素,加入螯合剂、离子液体组成、时间、溶液p H以及离子液体用量等,并浅析了离子液体的回用。为离子液体分离富集镉离子的进一步研究提供理论依据。     

SEPARATION OF AROMATIC AND ALIPHATIC HYDROCARBONS WITH IONIC LIQUIDS

Naphtha cracker feeds may contain 10–25 wt% aromatic compounds. Removal of these aromatic compounds from the feed to the cracker would offer several advantages: higher capacity, higher thermal efficiency, and less coke formation. In this work, we investigated the separation of toluene from heptane by extraction with ionic liquids.

Several ionic liquids are suitable for extraction of toluene from toluene/heptane mixtures. The selectivities for the aromatic/aliphatic hydrocarbon separation with all ionic liquids tested increase with decreasing aromatic content in the feed. The toluene/heptane selectivities at 10% toluene in the feed at T = 40°C and 75°C with several ionic liquids ([emim]HSO₄, [mmim] methylsulfate, [emim] ethylsulfate, [bmim]BF₄, [emim] tosylate, [mebupy]BF₄, and [mebupy] methylsulfate) are a factor of 1.5–2.5 higher than those obtained with sulfolane, which is a conventional solvent for the extraction of aromatic hydrocarbons from a mixed aromatic/aliphatic hydrocarbon stream. The three most suitable ionic liquids from the ionic liquids tested for the separation of aromatic and aliphatic hydrocarbons are [mebupy]BF₄, [mebupy]CH₃SO₄, and [bmim]BF₄ and at 75°C also [emim] tosylate. The ionic liquid [mebupy]BF₄ is selected for further testing in our extraction pilot plant.

Because ionic liquids have a negligible vapor pressure, evaporating the extracted hydrocarbons from the ionic liquid phase could achieve the recovery of the ionic liquid. A conceptual process scheme for the extraction has been set up. Preliminary calculations show that both the investment costs and the energy costs will be considerably lower with ionic liquids than with sulfolane as the solvent.     

SEPARATION OF AROMATIC AND ALIPHATIC HYDROCARBONS WITH IONIC LIQUIDS

Naphtha cracker feeds may contain 10-25 wt% aromatic compounds. Removal of these aromatic compounds from the feed to the cracker would offer several advantages: higher capacity, higher thermal efficiency, and less coke formation. In this work, we investigated the separation of toluene from heptane by extraction with ionic liquids.

Several ionic liquids are suitable for extraction of toluene from toluene/heptane mixtures. The selectivities for the aromatic/aliphatic hydrocarbon separation with all ionic liquids tested increase with decreasing aromatic content in the feed. The toluene/heptane selectivities at 10% toluene in the feed at T = 40°C and 75°C with several ionic liquids ([emim]HSO₄, [mmim] methylsulfate, [emim] ethylsulfate, [bmim]BF₄, [emim] tosylate, [mebupy]BF₄, and [mebupy] methylsulfate) are a factor of 1.5-2.5 higher than those obtained with sulfolane, which is a conventional solvent for the extraction of aromatic hydrocarbons from a mixed aromatic/aliphatic hydrocarbon stream. The three most suitable ionic liquids from the ionic liquids tested for the separation of aromatic and aliphatic hydrocarbons are [mebupy]BF₄, [mebupy]CH₃SO₄, and [bmim]BF₄ and at 75°C also [emim] tosylate. The ionic liquid [mebupy]BF₄ is selected for further testing in our extraction pilot plant.

Because ionic liquids have a negligible vapor pressure, evaporating the extracted hydrocarbons from the ionic liquid phase could achieve the recovery of the ionic liquid. A conceptual process scheme for the extraction has been set up. Preliminary calculations show that both the investment costs and the energy costs will be considerably lower with ionic liquids than with sulfolane as the solvent.     

CAPILLARY ELECTROKINETIC SEPARATION OF POLYCYCLIC AROMATIC HYDROCARBONS USING CETYLPYRIDINIUM BROMIDE

Polycyclic aromatic hydrocarbons (PAHs) including isomeric pairs were separated in capillary electrokinetic chromatography using a cationic surfactant cetylpyridinium bromide (CPBr) as additive. With addition of 2 mM CPBr into the running electrolyte, dynamic coating occurs in the capillary and EOF is reversed. Changes of electroosmotic and electrophoretic mobilities with increasing CPBr concentration were investigated. Under optimum separation conditions, running electrolyte contains 50% MeCN, 20 mM acetate, and 40 mM CPBr at pH = 4.0. Using high concentration of organic solvent, aggregation of surfactants into micelles is prevented. Significant retentions indicate solvophobic, n- and π-electron interactions between CPBr monomers and PAHs.     

离子液体在催化反应和萃取分离中的研究和应用进展

离子液体研究已从“绿色”化学化工快速扩展到功能材料、能源、资源环境以及生命科学等领域,典型地体现了科学技术发展中的多学科交叉与综合.本文就离子液体在催化反应和萃取分离中的研究进展进行初步的总结与评述,以期为以后的研究工作提供参考.     

TOXICOKINETICS OF POLYCYCLIC AROMATIC HYDROCARBONS FROM CONTAMINATED SEDIMENT BY THE AMPHIBIAN LARVAE (PLEURODELES WALTL)

The molecular phototransformation mechanism of nitroarenes, genotoxic and ubiquitous pollutants in the atmosphere, is still under debate. With increasing exposure to radiation 1,6- and 1,8-dinitropyrene (DNP) in acetonitrile showed a decrease in their characteristic absorption bands (396 and 411 nm, respectively) in the presence of O ₂ , N ₂ and H ₂ O, and an increase in the 220–390 nm region and above 450 nm, indicating their photodegradation and transformation. The resulting photoproducts were highly fluorescent, presenting a broad emission band around 520–540 nm. Oxygen reactive species did not seem to be produced in the principal photodegradation pathways, since photodegradation rates were similar to those in anaerobic samples. In the presence of O ₂ or N ₂ 1,6-DNP photodegraded 4 times faster than 1,8-DNP, while in the presence of water is 1.5 times faster. Two chromatographic fractions were separated, and identified as pyrenediones using authentic samples and reported spectral data for hydroxy-nitropyrenes. Other chromatographic fractions are still to be identified. The properties of the identified products suggested that these were formed through a nitro-nitrite rearrangement.     

SYNERGISTIC SELECTIVE EXTRACTION OF ACTINIDES(III) OVER LANTHANIDES FROM NITRIC ACID USING NEW AROMATIC DIORGANYLDITHIOPHOSPHINIC ACIDS AND NEUTRAL ORGANOPHOSPHORUS COMPOUNDS

ABSTRACT

New aromatic dithiophosphinic acids (R₂PSSH) with R = C₆H_5?, ClC₆H_4?, FC₆H_4? and CH₃C₆H_4? were synthesized, characterized and tested as potential separating agents for trivalent actinides over lanthanides. The extraction of Am(III), Eu(III) and other lanthanides was carried out from nitric acid medium with mixtures of R₂PSSHS and neutral organophosphorus compounds. There was no detectable extraction when R₂PSSHS were used alone as extractants for either Am(III) or Eu(III) (D_AM,EU.< 10^?3) under the experimental conditions used in this study. High separation factors (D_AM/D_EU > 20) with D_AM > 1 were achieved in the nitric acid range 0.1-1 mol/L by means of a synergistic mixture of bis(chloro-phenyl)dithiophosphinic acid + tributylphosphate (TBP), irioctylphosphine oxide (TOPO) or tributylphosphine oxide (TBPO). The high radiation resistance (up to 10⁶ Gy absorbed γ-doses) of the extractants was also demonstrated.     

气液色谱法测定正己烷在不同类型固定液中的无限稀活度系数

利用气液色谱法测定了正己烷在正十六烷～正二十三烷、角鲨烷、角鲨烯、二苯甲烷、联苄、丁二酸二正丁酯、丁二酸二异辛酯、已二酸二正辛酯、癸二酸二正辛酯中不同温度下的无限稀活度系数。由Ｆｌｏｒｇ－Ｈｕｇｇｉｎｓ理论预测的正己烷的活度系数与实验值相近，由此进一步得到了二组分体系的相互作用参数值及各溶剂的溶解度参数值。     

SIMULTANEOUS GC/MS ANALYSIS OF POLYCYCLIC AROMATIC HYDROCARBONS AND THEIR NITRATED DERIVATIVES IN ATMOSPHERIC PARTICULATE MATTER FROM WORKPLACES

Abstract

PAH are routinely analyzed using HPLC/FD. This technique is unsuitable for analyzing NPAH. This study aims at developing a reliable method, using GC/MS, and applying this technique to actual samples from small volumes of atmospheric particulate matter from workplaces. Mixtures of PAH and NPAH were separated by GC/MS and detected by electronic impact (EI) or negative ion chemical ionization (NICI). Analyses on twelve actual samples were thus carried out by sampling a small volume of atmosphere (≈0.5 m ³ ) from five different industrial workplaces. Samples displayed wide differences from one industrial workplace to another, and this can be explained by the specific methods applied. The PAH and NPAH concentrations also varied with time in the same industrial workplace. NPAH concentrations were not correlated with PAH concentrations, underscoring the complex chemical mechanisms involved in NPAH formation. PAH and NPAH formation appeared to be dependent on both industrial activities and uncontrolled physicochemical conditions.     

RISK OF CONTAMINATION FOR EDIBLE VEGETABLES GROWING ON SOILS POLLUTED BY POLYCYCLIC AROMATIC HYDROCARBONS

Former industrial sites represent a potential source for food chain contamination if they are converted to residential use where garden practices may be undertaken. In order to assess the risk for human health through vegetable consumption, two research programs were initiated to evaluate the bioavailability of selected PAHs and their potential transfer to edible parts of different vegetables. With this intention, we tested four methods to predict the potential contamination of vegetables growing on polluted soils (wild plant analysis, cropping of vegetables on polluted soils, models of organic pollutant transfer, soil selective chemical extractions). Various wild plant species colonized naturally the contaminated soils of former industrial sites and edible vegetables grew on these soils without symptoms of phytotoxicity. When soils presented concentrations of pollutants compatible with residential land use, no significant concentration of PAHs was measured in the different tissues. Moreover, in soils highly polluted by PAHs significant soil-root-leaf transfers of pollutants were showed, but no PAHs were found in fruits and in storage organs. We noted a similar behavior of cultivated vegetables and of their wild analogous plants facing organic pollutants. In another way, two selective chemical extraction methods correctly evaluated the soil PAH bioavailable fraction for plants growing on low-polluted soil. This would allow the use of wild plants naturally present on polluted soils in parallel with soil chemical extraction methods to assess the risk of contamination of the food chain.     

LONG TERM MONITORING OF POLYCYCLIC AROMATIC HYDROCARBONS (PAHS) IN BLUE MUSSELS (Mytilus edulis) FROM A REMOTE SCOTTISH LOCATION

Farmed mussels have been collected on a monthly basis since 1999 from a remote site on the west coast of Scotland for polycyclic aromatic hydrocarbon (PAHs) analysis with the aim of establishing background concentrations as a benchmark against which to assess any environmental incident. Total PAH (2- to 6-ring parent and alkylated) concentrations ranged from 12.5 to 151.2 μg kg^?1 wet weight. Seasonal trends were evident with concentrations being significantly higher for samples collected between November and March compared to those collected between April and October. By taking the median of medians for each of these time periods two background concentrations are suggested for the total PAH concentrations (2- to 6-ring PAHs parent and alkylated); for April to October: 31.2 μg kg^?1 wet weight and for November to March: 62.9 μg kg^?1 wet weight. Individual PAH concentrations were mainly below the OSPAR Background Assessment Concentrations (BACs), where they are specified, and were only exceeded for the heavier 4- and 5-ring PAHs (fluoranthene, pyrene, benz[a]anthracene and benzo[a]pyrene) in samples collected between November and March. Differences were also seen in the PAH profiles with season. Mussels collected between November and March had a higher proportion of the heavier PAHs compared to mussels collected in the summer and autumn.