Effect of Ionic Liquids on Surface and Aggregation Properties of Non-ionic Surfactant Triton™ X-100 in Aqueous Media

The effect of the hydrophilic ionic liquids (ILs) 1-butyl-2,3-dimethylimidazolium bromide [bdmim][Br] and 1-hexyl-2,3-dimethylimidazolium bromide [hdmim][Br] on the aggregation and surface active behaviour of the non-ionic surfactant Triton? X-100 (TX-100) was studied in aqueous media. Several aggregation properties of TX-100 + IL/water systems, such as critical micelle concentration (CMC), surface active parameters, aggregation number (N _agg) and aggregate size, were determined by surface tension, fluorescence and dynamic light scattering (DLS) techniques. It was found that the average micellar size and aggregation number decrease, whereas the CMC increases with increasing concentration of ILs. Interestingly, the CMC value of TX-100 is reduced slightly below 0.5 wt% of both the ILs in the medium. At higher wt% of IL in the system the CMC increases. It was demonstrated that ILs [bdmim][Br] and [hdmim][Br] can be judiciously used at different wt% for modifying the physico-chemical properties of TX-100.     

Interaction Between Ionic Liquids and Gemini Surfactant: A Detailed Investigation into the Role of Ionic Liquids in Modifying Properties of Aqueous Gemini Surfactant

Tuning physicochemical properties of aqueous surfactant solutions comprised of normal or reverse micelles by external additives is of utmost importance due to the enormous application potential of surfactant‐based systems. Unusual and interesting properties of environmentally benign ionic liquids (IL) make them suitable candidates for this purpose. To understand and establish the role of IL in modifying properties of aqueous gemini surfactants, we studied the effect of the IL, 1‐hexyl‐3‐methylimidazolium bromide ([Hmim][Br]) and 1‐octyl‐3‐methylimidazolium bromide ([Omim][Br]) on the properties of the aqueous cationic gemini surfactant 1,6‐hexanediyl‐α,ω‐bis(dimethyltetradecyl)ammonium bromide (14‐6‐14,2Br^?). The behavioral changes were investigated by measuring the critical micelle concentration (CMC) using electrical conductance, surface tension, dye solubilization and fluorescence probe measurements at 298.15 K. It was observed that the CMC of 14‐6‐14,2Br^? gemini surfactant decreases with addition of IL, thus favoring the micellization process. An increase in micellar size was observed at lower IL concentration using dynamic light scattering, with a decrease in aggregation number (N_agg) determined from fluorescence probe quenching measurements. It is noteworthy that the extent of modulation of the micellar properties is different for both the IL due to their structural differences. IL behave like electrolytes at lower concentrations and cosurfactants at higher concentrations and form mixed micelles with the cationic gemini surfactant showing an increase in N_agg.     

Physical and electrochemical properties of 1-butyl-3-methylimidazolium bromide, 1-butyl-3-methylimidazolium iodide,and 1-butyl-3-methylimidazolium tetrafluoroborate

The density, viscosity, refractive index, heat capacity, heat of dilution, ionic conductivity, and electrochemical stability of 1-butyl-3-methylimidazolium bromide ([bmim][Br]), 1-butyl-3-methylimidazolium iodide ([bmim][I]), and 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim][BF₄]) were measured at room temperature or over a temperature range of 293.2 to 323.2 K. The density and refractive index values of [bmim][I] appeared to be the highest among three ionic liquids (ILs). However, the experimental viscosity values of [bmim][Br] were higher than those of [bmim][BF₄], while the heat capacities and heats of dilution of [bmim][BF₄] were higher than those of [bmim][Br]. The cyclic voltammogram of [bmim][br] and [bmim][BF₄] indicated electrochemical windows in the stability range from 2.7 V of [bmim][[Br] to 4.7 V of [bmim][BF₄].     

含离子液体乙腈-正丙醇体系的等压汽液平衡

常压(101.3 kPa)下, 测定了如下体系的汽液平衡数据:乙腈-正丙醇-氯化1-苄基-3-甲基咪唑([BzMIM][Cl])、乙腈-正丙醇-溴化1-苄基-3-甲基咪唑([BzMIM][Br])、乙腈-正丙醇-溴化1-己基-3-甲基咪唑([HMIM][Br]), 考察了3种离子液体对乙腈-正丙醇体系相平衡行为的影响。实验结果表明, 3种离子液体都能够提高乙腈对正丙醇的相对挥发度, 3种离子液体提高相对挥发度的顺序为 [BzMIM][Cl] > [BzMIM][Br] > [HMIM][Br]。用NRTL模型对测得的汽液平衡数据进行了关联, 关联结果与实验结果具有良好的一致性。     

Surface tension and viscosity of 1-butyl-3-methylimidazolium iodide and 1-butyl-3-methylimidazolium tetrafluoroborate, and solubility of lithium bromide+1-butyl-3-methylimidazolium bromide in water

The surface tension and viscosity of 1-butyl-3-methylimidazolium iodide ([bmim][I]) and 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim][BF₄]) were measured over a temperature range of 298. 15 to 323.15 K. It was found that both the viscosity and surface tension decrease with increasing temperature and that the surface tension and viscosity values of [bmim][I] were higher than those of [bmim][BF₄]. Additionally, the solubility of lithium bromide (2)+1-butyl-3-methylimidazolium bromide ([bmim][Br]) (3) in water (1) was measured at three different mass ratios (w₂/w₃=4 and 7, w₃=0) by using a visual polythermal method. The solubility of the suggested systems was better than that of lithium bromide in water.     

疏水性离子液体萃取芳香化合物及其再生

利用疏水性离子液体1-丁基-3-甲基咪唑六氟磷酸盐[Bmim][PF6]、1-丁基-3-乙基咪唑六氟磷酸盐[Beim][PF6]、1-丁基-3-甲基咪唑双三氟甲磺酰亚胺盐[Bmim][Tf2N]对水溶液中的9种芳香化合物进行萃取,以苯胺为代表对萃取工艺进行了优化,考察了乙醚、正丁醇等低极性溶剂对离子液体的再生情况. 结果表明,在室温下,当相比O/A=0.2、时间为10 min时,[Bmim][PF6]对苯胺的萃取率达87.2%,分配系数为34.1,效果明显高于甲苯、正辛醇等传统有机溶剂. 芳香化合物的分子结构对萃取有较大影响,萃取率及分配系数随溶质疏水性增加而增加. 用乙醚作为反萃剂效果较好,苯胺和离子液体的回收率分别为93.1%和95.2%,溶质及离子液体均能实现资源化回收利用.     

1-氨丙基-3-甲基咪唑溴盐水溶液的汽液相平衡

1-氨丙基-3-甲基咪唑溴盐([APMIm][Br])是一种对CO₂有良好吸收性能的功能型离子液体,在工业中可采用水溶液来实现高效能的吸收和解吸循环过程,因此对其水溶液特性的研究至关重要。对[APMIm][Br]水溶液在中低温度下的汽液相平衡进行了测量,获得可靠的实验数据,从而揭示其水溶液特性。实验温度范围为278.15～348.15 K,[APMIm][Br]在水溶液中质量分数分别为10.0%、20.3%、29.5%、40.0%、57.5%、75.3%、84.0%、88.9%、90.9%。考虑了低温下离子液体分子在水溶液中的强缔合特性,采用带缔合惰化因子的离子液体水溶液活度模型对实验数据进行了拟合,实验值与计算结果符合很好,平均相对误差为2.15%。     

Modified g-C3N4 derived from ionic liquid and urea for promoting visible-light photodegradation of organic pollutants

In this work, modified g-C₃N₄ was fabricated successfully by calcination of ionic liquid (IL) and urea. The addition of IL changed the polymerization mode of urea, induced the self-assembly of urea molecules, modified the morphological structure of the tightly packed g-C₃N₄, and extended the electron conjugation system. When using 1-butyl-3-methylimidazolium chloride ([Bmim]Cl) as a modifier, the heteroatom Cl could be inserted into the g-C₃N₄ to optimize the electronic structure. The results of characterizations indicate that the unique structure of modified g-C₃N₄ has an expanded electron delocalization range, introduces an interlayer charge transmission channel, promotes the charge transmission, reduces the band gap, enhances the absorption of visible light, and inhibits electron-hole recombination. Modified g-C₃N₄ showed excellent photocatalytic performance for the degradation of rhodamine B and tetracycline. Furthermore, the effect of different anions in 1-butyl-3-methylimidazolium salts ([Bmim]Cl, [Bmim]Br, [Bmim][BF₄], and [Bmim][PF₆]) on the structure and function of g-C₃N₄ are discussed.     

Thermal and electrochemical properties of morpholinium salts with bromide anion

The present work is a study of the thermal properties and electrochemical stabilities of N-ethyl-N-methylmorpholinium bromide ([Mor_1,2][Br]), N-butyl-N-methylmorpholinium bromide ([Mor1_1,4][Br]), N-octyl-N-methylmorpholinium bromide ([Mor1_1,8][Br]), N-dodecyl-N-methylmorpholinium bromide ([Mor1_1,12][Br]), and N,N-dihydroxyethylmorpholinium bromide ([DHEMor][Br]). The melting points, decomposition temperatures, and electrochemical stabilities of the salts were measured by DSC (differential scanning calorimetry), TGA (thermogravimetric analysis), and CV (cyclic voltammogram), respectively. All salts were decomposed below approximately 230.00 °C and their melting points were above 100.00 °C except [DHEMor][Br], which melted at 75.17 °C. [DHEMor][Br] appeared to possess the most wide liquid-phase range between melting point and decomposition temperature. The electrochemical windows of salts ranged from 3.3 V for [Mor_1,8][Br] to 3.6 V for [Mor_1,4][Br] and thus did not show any noticeable variation with cations used for salt synthesis.     

离子液体对溶菌酶晶体形态和活性的影响

以鸡蛋清溶菌酶为模型蛋白,采用冷却结晶法结晶以及浊度法测定酶活性,研究了分别添加4种亲水性离子液体(1-丁基-3-甲基咪唑四氟硼酸盐([C₄mim]BF₄)、1-丁基-3-甲基咪唑氯盐([C₄mim]Cl)、1-丁基-3-甲基咪唑溴盐([C₄mim]Br)和1,3-二甲基咪唑碘化物([dmim]I))条件下溶菌酶晶体形态和晶体活性的变化。利用光学显微镜对溶菌酶结晶过程的晶体形态进行分析,结果表明添加离子液体会影响溶菌酶的晶体形态和尺寸。离子液体[C₄mim]BF₄介导的溶菌酶形成棒状晶体。与未添加离子液体相比,[C₄mim]Cl和[C₄mim]Br均未改变溶菌酶晶体形态,均呈块状晶体,但[C₄mim]Cl和[C₄mim]Br促进溶菌酶晶体生长,晶体尺度均增加。而添加[dmim]I,溶菌酶呈现针状晶体。采用浊度法测定溶菌酶晶体活性,结果表明不同的离子液体对溶菌酶晶体的活性...     

Synthesis and evaluation of micellar properties and antimicrobial activities of imidazole‐based surfactants

The synthesis of two types of imidazole‐based surfactants, [(ROCOCH₂MIm)Br] and [(RNHCOCH₂MIm)Br], of varying chain lengths (C₁₀, C₁₂ and C₁₆), was conducted in the present work. The synthesis involves an initial reaction of bromoacetic acid with fatty alcohols or fatty amines, followed by quaternization with N‐methyl imidazole. The micellar properties of all the synthesized compounds were determined using surface tensiometry and compared with [(RMIm)Br], a well‐studied alkyl‐substituted imidazole‐based surfactant. Within the same homologous series, a decrease in critical micelle concentration (cmc) was observed with increasing alkyl chain length in all three types of cationic surfactants. Introduction of an ester [(ROCOCH₂MIm)Br] or an amide group [(RNHCOCH₂MIm)Br] in the alkyl chain lowers the cmc when compared to a cationic surfactant without functional group, [(RMIm)Br]. The synthesized surfactants were also assayed for antimicrobial activities and found to possess good activities against selected strains.     

Micellization behavior of ionic liquid surfactants with two hydrophobic tail chains in aqueous solution

The drop volume method was used to determine the surface tensions of two series of polymerizable ionic liquid surfactants, namely, 1‐acryloyloxypropyl‐3‐alkylimidazolium chloride [APC_nim][Cl] (n = 8, 10, 12) containing two hydrophobic tail chains and 1‐propionyloxypropyl‐3‐alkylimidazolium chloride [PPC_nim][Cl] (n = 8, 10, 12), which showed similar structures with [APC_nim][Cl] (n = 8, 10, 12) at 25°C. The surface properties of the surfactants were also compared. Furthermore, the thermodynamic behavior of [PPC_nim][Cl] (n = 10, 12, 14) micellization in aqueous solution and the enthalpy–entropy compensation phenomenon were studied. The two kinds of surfactants had high surface activity. Double bonds had almost no effect on the surface properties of [APC_nim][Cl]. The micellization of [PPC_nim][Cl] in aqueous solution was spontaneous and entropy‐driven. For the surfactant with specific structure, micellization ability initially increased and then decreased with temperature increase. The entropic contribution to Gibbs free energy change tended to decrease, whereas the enthalpic contribution increased. In addition, the enthalpy–entropy compensation phenomenon occurred during the micellization process. For all [PPC_nim][Cl], the compensation temperature was (314 ± 1) K, which remained unaffected by the surfactant molecular structure. However, when the hydrophobic carbon chain length increased, both micelle formation ability and stability increased. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Solubility of CO2 in three cellulose-dissolving ionic liquids

The solubility of CO₂ in three cellulose-dissolving ionic liquids (1-ethyl-3-methylimidazolium diethylphosphate, [Emim][DEP], 1-allyl-3-methylimidazolium chloride, [Amim][Cl], and 1-butyl-3-methylimidazolium chloride, [Bmim][Cl]) at temperatures within 298 and 356 K and pressures up to 6.5 MPa was determined using a Van Ness-type apparatus (static isochoric). It was demonstrated that this device can work in isothermal and isoplethal modes, being the latter faster and more precise. Moreover, it was possible to determine CO₂ solubilities in metastable liquid [Bmim][Cl]. Experimental data were modeled using the Extended Henry's law correlation and the group contribution equation of state. New parameters for the binary interaction of CO₂ with ionic liquid groups were calculated.     

萃取精馏分离甲醇-丁酮萃取剂的选择

为了解决工业生产中甲醇-丁酮共沸体系难分离的问题,本研究采用一步法合成了N-乙基吡啶溴盐([EPy][Br])、N-丁基吡啶溴盐([BPy][Br])和N-己基吡啶溴盐([HPy][Br])3种离子液体(IL),测定了101.3 kPa下这3种离子液体对甲醇-丁酮共沸物系的溶剂选择性,并考察了溶剂比对其选择性的影响,同时将离子液体的分离性能与有机溶剂进行了比较。实验结果表明:合成的3种离子液体都可提高甲醇对丁酮的相对挥发度,它们的选择性大小顺序为[EPy][Br]> [BPy][Br]> [HPy][Br],同时,它们的选择性随溶剂比的增加而增大,与常规有机溶剂相比,离子液体作为萃取剂具有显著优势。因此,可以选用[EPy][Br]作为分离甲醇-丁酮共沸物系的萃取剂。     

乙腈+[C4mim][Cl]、乙腈+[C4mim][BF4]、乙腈+[C6mim][Cl]的气液平衡测定与关联（英文）

Vapor pressures were measured for acetonitrile+1-butyl-3-methylimidazolium chloride ([C4mim][Cl]),+1-butyl-3-methylimidazolium tetrafluoroborate ([C4mim][BF4]) and+1-hexyl-3-methylimidazolium chloride ([C6mim][Cl]) at temperatures of 313 to 353 K by a quasi-static method. The experimental data for the binary sys-tems were correlated by the non-random two liquid (NRTL) equation with an average absolute relative deviation (AARD) of within 1.84%. The results indicate that the three ionic liquids (ILs) can result in a negative deviation from the Raoult's law for the binary solutions containing acetonitrile, and the affinity between ILs and acetonitrile mole-cules fol ows the order [C4mim][BF4]+acetonitrile N [C4mim][Cl]+acetonitrile N [C6mim][Cl]+acetonitrile.     

Solubility of neutral and charged polymers in ionic liquids studied by laser light scattering

The solubility and chain conformation of different types of homopolymers in low viscosity ionic liquids (ILs), 1-allyl-3-methylimidazolium chloride ([AMIM][Cl]) at 50 °C and 1-butyl-3-methylimidazolium formate ([BMIM][COOH]) at 25 °C, were studied by laser light scattering (LLS). For neutral polymers, such as polyvinyl alcohol and polysulfonamide, aggregation occurred in all the cases except for polyvinyl alcohol in [BMIM][COOH]. For negative polyelectrolytes, such as DNA and polystyrene sulfonate, single chain conformation was observed. However, the hydrodynamic radius of both polymers was much smaller than that in good solvents, suggesting that the chains were condensed. Cellulose was soluble in [AMIM][Cl], and non-diffusive mode was observed by dynamic light scattering. Zeta potential analysis indicated that cellulose exhibited the feature of polyelectrolyte. The solubility of homopolymers could be qualitatively explained by treating polymer/IL as a ternary system: polymer, cation, and anion. It was the mutual interactions determined the solubility and conformation of polymers in ILs.     

Vapor pressure measurement and correlation of acetonitrile+1-butyl-3-methylimidazolium chloride,+1-butyl-3-methylimidazolium tetrafluoroborate,and+1-hexyl-3-methylimidazolium chloride

Vapor pressures were measured for acetonitrile+1-butyl-3-methylimidazolium chloride ([C4mim][Cl]),+1-butyl-3-methylimidazolium tetrafluoroborate ([C4mim][BF4]) and+1-hexyl-3-methylimidazolium chloride ...     

1-丁基-3-甲基咪唑表面活性离子液体的界面膨胀流变行为研究

研究了1-丁基-3-甲基咪唑十二烷基硫酸盐([bmim][DS])和1-丁基-3-甲基咪唑二(2-乙基己基)磺基琥珀酸酯盐([bmin][AOT]两种表面活性离子液体在正庚烷/水界面的动态界面张力和膨胀特性。比较了[bmim][DS]或[bmin][AOT]和传统表面活性剂十二烷基硫酸钠(SDS)或二(2-乙基己基)磺基琥珀酸酯钠(Na[AOT])之间的膨胀弹性,并且考察了1-丁基-3-甲基咪唑阳离子之间静电相互作用对界面膜特性的影响。另外,通过对比[bmim][DS]和[bmim][AOT]在不同浓度下的膨胀弹性,验证了烷基链数量的改变对界面膨胀流变行为的影响。     

Extractive Desulfurization of Fuel Oils with Thiazolium-Based Ionic Liquids

A new class of green solvents, known as ionic liquids (ILs), has recently been the subject of intensive research on the extractive desulfurization of fuel oils because of the limitation of the traditional hydrodesulfurization method in catalytically removing thiophenic sulfur compounds. In this work, four thiazolium-based ILs, that is, 3-butyl-4-methylthiazolium dicyanamide ([BMTH][DCA]), 3-butyl-4-methylthiazolium thiocyanate ([BMTH][SCN]), 3-butyl-4-methylthiazolium hexafluorophosphate ([BMTH][PF₆]), and 3-butyl-4-methylthiazolium tetrafluoroborate ([BMTH][BF₄]), are synthesized. The extractive capability of these ILs in removing thiophene (TS) and dibenzothiophene (DBT) from model fuel oils is investigated. [BMTH][DCA] and [BMTH][SCN] present better extractive desulfurization capability than [BMTH][BF₄] and [BMTH][PF₆], which may be ascribed to the additional π?π interaction between –C≡N (in [BMTH][DCA] and [BMTH][SCN]) and thiophenic ring (in TS and DBT); DBT in diesel fuel is more efficiently extracted than TS in gasoline. [BMTH][DCA] offers the best desulfurization results, where 64% and 45% sulfur removal are obtained for DBT and TS, respectively, at IL:oil mass ratio of 1:1, 25°C, 20 min. [BMTH][DCA] is thus selected to systematically investigate the effects of temperature, IL:oil mass ratio, initial sulfur content, multiple-extraction, and IL regeneration on desulfurization. The mutual solubility of [BMTH][DCA] with fuel oil is also determined. It is observed that the desulfurization capability is not too sensitive to temperature and initial sulfur content, which is desired in industrial application; the sulfur contents in gasoline and diesel fuel are reduced from 558 ppm to 20 ppm (after 5 cycles) and from 547 ppm to 8 ppm (after 4 cycles), respectively. This work may show a new option for deep desulfurization of fuel oils.