纤维素在咪唑基离子液体中的降解行为

为了解纤维素在咪唑类离子液体中的降解行为,用正交试验法分析了温度、转速、时间对纤维素降解程度的影响,并比较了纤维素在四种离子液体中的降解行为。结果表明,纤维素在1-乙基-3-甲基咪唑醋酸盐（[EMIM]Ac）中的最佳溶解条件为,温度80℃,时间1h,转速230r/min。温度对纤维素降解程度影响最大,其次为时间和转速。同条件下,纤维素在[EMIM]Ac中的降解最轻,在1-烯丙基-3-甲基咪唑氯盐（[AMIM]Cl）中降解最严重。没食子酸丙酯可显著缓解纤维素在离子液体中的降解程度。[EMIM]Ac、1-丁基-3-甲基咪唑醋酸盐（[BMIM]Ac）遇没食子酸丙酯显紫红色,并在纤维素溶解后颜色消失。     

Degumming of Tasar silk using imidazolium-based ionic liquids

Abstract

In the present work, degumming of Tasar silk was carried out using novel reagents, the ionic liquids (ILs), 1-butyl-3-methylimidazolium chloride [BMIM]Cl and 1-butyl-3-methyl-imidazolium hydrogen sulphate [BMIM]HSO₄.The results on weight loss, tensile strength loss and absorbency were compared with soda ash-H₂O₂ method. These treatments were carried out under conventional heating, sonication and microwave irradiation as different techniques of energy input. The ILs showed higher weight loss and absorbency with negligible strength loss as compared to the soda ash-H₂O₂ method, [BMIM]Cl being the most effective with further advantage of working at nearly neutral pH. The treatments under sonication and microwave showed increasingly higher efficiency as compared to the conventional heating. The chemical structure of Tasar silk, as estimated by FTIR spectroscopy, and the crystalline structure, as elucidated by X-ray diffraction, remained unchanged. SEM images showed that the surface of Tasar silk degummed with ILs was smoother. The dye uptake was nearly the same for all degummed samples. A further advantage is accrued by recyclability of ILs, which makes the process cost effective.     

不对称咪唑类离子液体对腈纶缓染性能的影响

为开发腈纶染色用环保型缓染剂,采用3只咪唑类离子液体作为亚甲基蓝上染腈纶纤维的缓染剂,并与常规缓染剂十六烷基三甲基溴化铵(CTAB)作比较,探究上述离子液体对亚甲基蓝上染腈纶纤维的影响。通过对缓染剂用量、染色温度和升温上染曲线的研究,以及染色转变温度的比较,探究出不同结构离子液体的缓染性能规律。结果表明,不对称烷基咪唑类离子液体对腈纶亚甲基蓝染色具有一定的缓染作用,随离子液体烷基碳链的增长,缓染作用不断增加,离子液体对染料最终上染率有一定的影响,但影响程度与常规缓染剂CTAB相近,可作为腈纶染色时优良的缓染剂。     

离子液体萃取脂肪酸甲酯性能研究

以咪唑型离子液体为萃取剂萃取长链脂肪酸甲酯。研究了离子液体阴离子的结构、相比和改性剂对萃取率的影响。[Bmim]Cl,[Bmim]Ac对脂肪酸甲酯有一定的萃取能力,但萃取率远远低于路易斯酸型离子液体[Bmim]Cl-xAlCl_3。对于[Bmim]Cl-xAlCl_3,萃取率随离子液体中AlCl_3比例的增加而增加。离子液体对脂肪酸甲酯的萃取能力与脂肪酸甲酯的分子结构有关,并受相比和改性剂影响。脂肪酸甲酯分子中双键个数越多、碳链长度越短,离子液体与石油醚的体积比越大,萃取率越高,当以x=1.35的咪唑型氯铝酸盐离子液体为萃取剂,离子液体与石油醚相比为1:2时,EPA的萃取率可以达到97.23%。萃取体系中加入乙酸乙酯或乙醇,将降低离子液体对脂肪酸甲酯的萃取能力。体系中200μL乙醇,EPA的萃取率由99.06%降低到15.10%。     

离子液体及聚离子液体在基于固相萃取技术的食品安全分析中的应用

由于食品样品多样性和复杂性,样品前处理成为食品安全分析的关键。固相萃取技术是食品安全分析中富集痕量组分、分离干扰物质的重要前处理方法。将具有特殊物理化学性质的离子液体及聚离子液体,应用于固相微萃取、基质固相分散萃取、分子印迹固相萃取、整体柱固相萃取等固相萃取技术中,改善了固相吸附剂性能,提高了固相萃取效率,实现了对食品样本中重金属离子、农兽药残留、违规或超标添加剂等的高效富集、分离,合并其他分离分析方法,达到了准确测定这些物质的含量的目的。离子液体及聚离子液体在食品分析的前处理中的应用将越来越广泛。     

离子液体在萃取分析领域的研究进展

离子液体是一类熔点低于100℃的有机熔融盐,通常由不对称的有机阳离子和阴离子组成,其性质可以通过改变阴阳离子组成灵活调节,被称为"设计者的溶剂"。由于其特殊的物理化学性质,离子液体在有机化学和分析化学等领域得到广泛应用,本文主要从离子液体类型、结构和性能等角度综述其在萃取前处理、色谱、毛细管电泳及电分析、光谱等领域中的研究进展,从应用机理角度对比不同离子液体在各领域应用中的优缺点,这对离子液体目前的应用状况及今后发展有较好的指导意义。通过对其发展前景的展望,表明离子液体在色谱分析和毛细管电泳等领域呈现出巨大的发展潜力。此外,设计研发新型离子液体和深入探讨其萃取分离机理,将有力推动其在分析科学领域中的研究发展,离子液体在复杂样品分析和痕量检测方面也将具有广阔的应用前景。     

Adsorption of alkylimidazolium and alkylpyridinium ionic liquids onto natural soils

The mechanism of ionic liquid sorption onto selected natural soils differing in their organic content, cation exchange capacity, and particle size distribution was investigated in detail. Isotherms were employed to describe sorption. In most cases,the maximum achievable surface concentrations were well above CEC values. This observation may indicate that initially sorbed solutes modify the sorbent, a process favoring further sorption. The experimental data suggest that if a multilayer process occurs, such a mechanism will be applicable to all ionic liquids; but saturation of the second layer occurred only with the longest alkyl chain compound. The shorter alkyl chain cations did not reach saturation in the concentration range investigated here. The influence of the varying pH and ionic strength of an aquifer on sorption strength was also determined.     

Strategies for detecting organic liquids on soils using mid-infrared reflection spectroscopy

Stand-off monitoring for chemical spills can provide timely information for cleanup efforts, and mid-infrared reflection spectroscopy is one approach being investigated for spill detection. Using laboratory data, anomaly and target detection strategies were examined for the detection of four different low-volatility organic liquids on two different soil types. Several preprocessing and signal-weighting strategies were studied. Anomaly detection for C-H bands was good using second-derivative preprocessing and provided similar performance to that of target detection approaches such as generalized least-squares and partial least-squares, with detections at soil loads of approximately 3-6 microg/cm2 a real dosage. Good performance was also found for the detection of P=O, O-H, and C=O stretching vibrational modes, but the optimal strategy varied. The simplicity and generality of anomaly detection is attractive; however, target detection provides more capability for classification.     

离子液体中制备多组分纤维素纤维

讨论了由纤维素和聚丙烯腈所组成的溶液在离子液体中形成纤维的过程。除了制备聚合物溶液外,还描述了由干湿法制备纤维素聚丙烯腈纤维的成形以及其纺织物理特性、保水性、原纤化趋势和染色性能。根据此工艺能获得一种既具特性又具可变性能的纤维,这些性能取决于所用聚合物的种类、溶剂以及之间的比例。     

Toxicity of ionic liquids and organic solvents to lactic acid-producing bacteria

In situ extractive fermentation of lactic acid using organic solvents has already been extensively investigated. Now ionic liquids are emerging as alternative solvents for volatile organic compounds traditionally used in liquid-liquid extraction. In this study, we examine whether lactic acid producing-bacteria can grow in the presence of a second phase of imidazolium-based ionic liquids or organic solvents. The lactic acid producing-bacteria used in this study are sensitive to organic solvents having 1 < log P < 4. We found that Lactobacillus delbruekii subsp. lactis NRIC 1683 could grow in the presence of a second phase of imidazolium-based ionic liquids as well as in the absence of the ionic liquids.     

微波协同离子液体的合成及在黄酮类化合物提取中的研究进展

阐述了离子液体的合成方法,并进行了系统的比较,微波协同合成离子液体具有耗时短、产率高及环境友好等优点;同时总结了微波协同合成离子液体的国内研究进展,并综述了离子液体在黄酮类化合物提取中的应用.     

Micron- and nano-cellulose fiber regenerated from ionic liquids

In this research, two types of ionic liquid, 1-butyl-3-methylimidazolium chloride (BMIMCl) and ionic liquid 1-ethyl-3-methylimidazolium acetate (EMIMAc), were used as recyclable solvents for dissolving raw cellulose in the spinning of micron- and nano-scale regenerated cellulose fiber. The approach for preparing the cellulose solution using these ionic liquids is described. A comparative study was also conducted on cellulose solubility, the spinning method, and cellulose fiber properties produced with each solvent. The experimental fibers are characterized in terms of fiber diameter, strength, thermal property, crystallinity, and content of solvent residual, using tensile test, thermogravimetric analysis, scanning electron microscopy, X-ray diffraction, and mass spectrometry. The study concluded that there was a significant difference in the tensile strength, but not in the elongation and modulus of the fibers regenerated from BMIMCl and EMIMAc. For crystal size, crystal orientation, and crystallinaty index, the BMIMCl-generated fiber had higher values than the EMIMAc-regenerated fiber. For the thermal property, EMIMAc fiber was more stable at higher temperatures than BMIMCl fiber. It was also revealed that the EMIMAc fiber had significantly less solvent residual content than the BMIMCl fiber.     

Capture of dioxins by ionic liquids

Dioxins are highly toxic compounds that mainly originate from incineration and combustion sources. In this work, a new, simple, and efficient approach for the absorption of dioxins from gaseous streams using thermally stable ionic liquids is proposed. The absorption process of nonchlorinated and chlorinated dibenzo-p-dioxin compounds was studied in the temperature range 100-200 degrees C. Imidazolium-, ammonium-, and guanidinium-based ionic liquids were designed for this specific purpose. It was observed that imidazolium cations having long alkyl side chains exhibit the highest absorption capacities, whereas the anion dicyanoamide [DCA] possesses higher absorption capacity than other anions studied. In a typical experiment, it was found that the ionic liquid 1-n-octyl-3-methyl imidazolium dicyanoamide [C8mim][DCA] can absorb more than 14% by weight of dibenzo-p-dioxin, 2-chlorodibenzo-p-dioxin, and 1,2,3,4-tetrachlorodibenzo-p-dioxin from a gaseous stream. A process for desorption of dioxins from the ionic liquid was tested, revealing that complete desorption can be achieved under a high vacuum. Additionally, the feasibility ofthe process was examined by carrying out experiments under real operating conditions of incineration and combustion processes. The success of the method heavily relies upon the design and selection of specific ionic liquids having enhanced affinity for the aromatic compound functionality present in dioxins and, simultaneously, possessing extremely low volatility and high chemical and thermal stability.     

离子液体催化合成酯类化合物的研究进展

酯化反应是重要的有机合成反应之一,在药物、材料、食品、香料、溶剂和增塑剂等生产中有广泛的应用.传统方法合成酯类化合物具有反应时间长、产率低、污染大、副反应多及后处理困难等缺点,离子液体区别于传统的溶剂和催化剂主要在于可通过改变其阴阳离子的结构进行调节,是可设计的绿色催化剂和溶剂,具有无腐蚀性、无毒、不挥发、不易氧化、液态范围宽、稳定性好、催化活性高等一系列独特性质,已被广泛应用于化学合成、分离工程和纳米材料制备等领域.离子液体催化酯化反应合成酯类化合物具有反应快、高效、产物易分离和安全等优点.本文综述了离子液体催化酯化反应合成脂肪酸酯类和芳香酯类的研究进展,并展望了该方法在酯类合成中的发展前景.     

离子液体的安全性研究进展

作为环境友好的“绿色溶剂”, 离子液体发展迅猛, 取得了令人瞩目的成果。作为新物质的离子液体, 其毒性、降解性、环境相容性等安全性问题已日趋成为人们必须高度重视解决的问题。受传统思想的影响, 有关离子液体安全性研究还是滞后于其应用研究。为此, 对离子液体的安全性进行综述就显得格外必要。本文对离子液体的细胞毒性、微生物毒性、高等动植物毒性和影响其毒性的离子液体本身的构效特性, 离子液体对环境作用性以及其降解性等安全性问题进行了简要综述, 并对离子液体安全性研究趋势作了展望。     

Factors affecting ionic liquids based removal of anionic dyes from water

Liquid--liquid extraction with imidazolium based ionic liquids--[C4mim][PF6], [C6miml][PF6], [C6mim[BF4], and [C8mim][PF6--is proposed for removal of anionic dyes including methyl orange, eosin yellow, and orange G from aqueous solutions. The effects of extraction time, pH of aqueous phase, structure of the ionic liquids, temperature, and KCl concentration on the extraction efficiencies have been studied. Extraction efficiencies of dyes were strongly affected by the pH of the aqueous phase. Under the optimized pH condition, 85-99% of methyl orange, almost 100% eosin yellows, and 69% of orange G in tested water samples were transferred into the ionic liquids in a single extraction. Extraction efficiency for a given dye was found to increase with increasing temperature and increasing alkyl chain length of cation of the ionic liquids. Presence of a small amount of KCl in the aqueous phase did not considerably improve the extraction efficiency of the dyes. Thermodynamic studies revealed that the extraction process was driven by hydrophobic interaction of the anionic dyes and the ionic liquids.