Separation of m-cresol from aromatic hydrocarbon and alkane using ionic liquids via hydrogen bond interaction

Low temperature coal tar contained a large amount of phenols, aromatic hydrocarbons and alkanes; the separation of phenols from coal tar has a great significance to the deep processing of coal tar. In this work, the separation of m-cresol from cumene and n-heptane by liquid–liquid extraction using ionic liquids (ILs) as extractants was studied. The suitable ILs were screened by conductor-like screening model for real solvents (COSMO-RS) model and the liquid–liquid phase equilibrium (LLE) experiments were to verify the accuracy of the screening results. The extraction conditions such as extraction time, extraction temperature and mass ratio of ILs to model oils were evaluated. An internal mechanism of the m-cresol extract by ILs was revealed by COSMO-RS calculation and FT-IR. The results showed that the selected ILs can extract m-cresol effectively from cumene and n-heptane, 1-ethyl-3-methylimidazolium acetate (emimCH₃COO) was the best extraction solvent. A hydrogen bond between anion of ILs and phenolic hydroxyl groups was observed. M-cresol in model oils could be extracted with extraction efficiencies up to 98.85% at an emimCH₃COO: model oils mass ratio of 0.5 and 298.15 K, emimCH₃COO could be regenerated and reused for 4 cycles without obvious decreases in extraction efficiency and extractant mass.     

High-efficiency separation and extraction of naphthenic acid from high acid oils using imidazolium carbonate ionic liquids

N-alkyl imidazolium carbonate ionic liquids were employed to separate and recover naphthenic acid from model oils.The effects of the cationic and anionic structures of ionic liquids and operating condi-tions on the deacidification performance were investigated.The deacidification performance of tradi-tional organic solvents was also investigated for comparison.The results indicated that the naphthenic acid could be completely removed from the model oil with a small mass ratio of ionic liquid to oil.The extracted naphthenic acid was regenerated with a recovery of up to 92％.In addition,imidazolium carbonate ionic liquids could be successfully regenerated and recycled.The mechanism of interaction between imidazole ionic liquids and the naphthenic acid molecules were explained by Gauss calculation.     

Densities and viscosities for ionic liquids [BMIM][BF4] and [BMIM][Cl] and their binary mixtures at various temperatures and atmospheric pressure

The density and viscosity of 1-butyl-3-methylimidazolium tetrafluoroborate [BMIM][BF₄] and 1-butyl-3-methylimidazolium chloride [BMIM][Cl] and their binary mixtures within the temperatures from 303.15 K to 323.15 K and at ambient pressure were determined in this work. The temperature dependences of density and viscosity were satisfactorily described with the linear model and the Vogel-Tammann-Fulcher type equation, respectively. The molar volume and viscosity of binary IL mixtures were predicted through ideal mixing rules showing that almost null deviations for IL mixtures were observed and their mixing was remarkably close to linear ideal behavior in the molar volumes, while comparatively large errors in viscosity occurred. Additionally, the molar volume of the investigated pure ILs and their mixtures could well be predicted by a predictive model presented by Valderrama et al. (Fluid Phase Equilib., 275 (2009) 145).     

离子液体溶剂浮选法分离富集盐湖卤水中的锂

首次将疏水性离子液体(IL)1-辛基-3-甲基咪唑六氟磷酸盐应用于溶剂浮选,对盐湖卤水中的锂进行富集分离,用火焰原子吸收光谱法对锂进行测定。考察了磷酸三丁酯(TBP)用量、相比V(O):V(A)、浮选时间、气体流速、浮选温度、共存离子、溶液的pH值对浮选率的影响。结果表明,最佳浮选条件为:浮选温度40℃,V(TBP):V(IL)=8:1,相比V(O):V(A)=5,气体流速为50 mL/min,溶液pH=2.5时浮选15 min,此时Li+的浮选率达到85%。离子液体作为浮选剂用来浮选Li+也适用于痕量锂的分析检测。     

Green synthesis of symmetrical imidazolium based ionic liquids and their application in the preparation of ZnO nanostructures

Environmentally benign procedure for synthesis symmetrical imidazolium based ionic liquids has been achieved. These Ionic liquids dissolved in water have been used as a reaction medium for synthesis of different morphologies of ZnO nanostructures like nanocoral, spherical and nanosheet by reflux method. The structural and optical properties of these ZnO particles were studied by using XRD, SEM and UV–visible. The characteristic results revealed that the anion and cation of ionic liquids effect on band gap and morphology of the zinc oxide species. The results show that the longer alkyl chain at positions 1 and 3 of imidazole ring ionic liquid cause the nanosheet morphology.     

Influence of flash sintering on the ionic conductivity of 8 mol% yttria stabilized zirconia

The ionic conductivity of flash-sintered, polycrystalline 8 mol% yttria stabilized zirconia (8YSZ) was enhanced compared with that of conventionally-sintered specimens. Flash sintering was carried out at a furnace temperature of 850 °C with an electric field of 100 V cm^–1 to initiate flash. The current density limit was varied between 60 and 100 mA mm^–2. Post-flash impedance measurements over the range 215–900 °C showed that both bulk and grain boundary conductivities had increased with the increased current density limit which was set prior to flash. The conductivity increases post-flash were ionic, not electronic, although electronic conductivity probably occurred, in addition to ionic conductivity, during flash. The conductivity increases were not attributable to sample densification or microstructural changes. The higher ionic conductivities are attributed to a change in YSZ defect structure that led to an increased concentration of mobile charge carriers; possible explanations for this are discussed.     

Improvement of biphasic polymerization by application of binary ionic liquid mixture

The mixture of two ionic liquids, 1-n-butyl-3-methylimidazolium and 1-(2-phenylethyl)-3-methylimidazolium chloroaluminates, [C₄-mim][AlCl₄] and [PhC₂-mim][AlCl₄], were applied as a medium to immobilize the Cp₂TiCl₂ titanocene catalyst for biphasic ionic liquid/hexane ethylene polymerization. The system makes possible to perform the reaction at lower temperatures, below the melting temperature of the aralkyl ionic liquid. A better separation of the ionic liquid phase was observed and an easier mass transfer of the polymer product from the ionic liquid to the hexane phase was obtained. The polyethylene reveals bimodal distribution of molecular weight. It is characterized by a high bulk density (500 g/dm³) and crystallinity degree (86%). The recycling of the ionic liquid medium containing the catalyst activated by AlEtCl₂, results in the highest yield obtained in such systems (550 kg PE(mol Ti)⁻¹).     

离子液体中制备壳聚糖季铵盐及其絮凝效果研究

采用一步合成法制备了离子液体甘氨酸盐酸盐,以其水溶液为反应介质,壳聚糖与2,3-环氧丙基三甲基氯化铵进行季铵化反应,得到壳聚糖季铵盐,并将其用于中药废水的絮凝处理.考察了温度、时间、反应物配比及离子液体浓度对季铵盐取代度的影响,以及季铵盐加入量、pH、搅拌时间对絮凝效果的影响.实验结果表明,在离子液体中进行的季铵化反应效率及产品取代度均高于常规的非均相反应,壳聚糖季铵盐能够有效去除中药废水的浊度和COD.     

Separation of chitin from shrimp shells enabled by transition metal salt aqueous solution and ionic liquid

Chitin is a widely used important industrial polymer mainly from shrimp shells, but its commercial preparation is under the great challenge of serious pollution due to the requirement of HCl and Na OH.Herein, we demonstrated that high purity chitin can be obtained from waste shrimp shells(WSSs) by cascade separation with transition metal salt aqueous solution and ionic liquid(IL). Firstly, calcium carbonate of WSSs was effectively removed in the metal salt aqueous solution driven by the ion exch...     

Rational design of double salt ionic liquids as extraction solvents: Separation of thiophene/n-octane as example

Although double salt ionic liquids (DSILs) offer significant advantages over classical two-ion ionic liquids as separation solvents, relevant studies are still scarce and a systematic DSIL selection method is thus highly desirable. In this contribution, a rational method for designing DSILs as extraction solvents is proposed and exemplified by the thiophene/n-octane separation. The effects of additional degrees of freedom for DSIL design (i.e., double cations and/or anions and the ion ratio) on the thermodynamic properties are first analyzed by COSMO-RS. Then, a multilevel DSIL design method combining the prediction of infinite dilution thermodynamic properties, the estimation of physical properties, the evaluation of phase equilibrium behavior, and the experimental validation is proposed. By applying this method, [C₂MIm][OAc] _x[NO₃]_1-x (x = [0, 1]) and [C₂MIm][OAc] _x[SCN]_1-x (x = [0.70, 1]) are identified as promising DSIL solvents for the thiophene/n-octane separation. Correspondingly, the liquid–liquid equilibria of {DSILs + thiophene + n-octane} with the designed DSILs are experimentally studied.     

The assessment of removing strontium and cesium cations from aqueous solutions based on the combined methods of ionic liquid extraction and electrodeposition

The extraction of Sr²⁺ and Cs⁺ from aqueous solutions by using the ionophores dicyclohexano-18-crown-6 (DCH18C6) and calix[4]arene-bis(tert-octylbenzo-crown-6) (BOBCalixC6), respectively, was demonstrated in the hydrophobic, room-temperature ionic liquid (RTIL), tri-1-butylmethylammonium bis((trifluoromethyl)sulfonyl)imide (Bu₃MeN-TFSI). The water contents of several hydrophobic ionic liquids and the absorption/desorption reversibility of oxygen and moisture in the Bu₃MeN-TFSI ionic liquid were determined by electrochemical techniques. The relationship between the distribution coefficient, D_M, and the concentration ratios of C_ionophore,IL/C_{metal ion,aq} were investigated. The values of D_M increase with increasing the concentration ratios and they are also influenced with the counter ions of Sr²⁺ and Cs⁺ in the aqueous solutions. In the previous study, it was demonstrated that the Sr²⁺ and Cs⁺ cations in the Bu₃MeN-TFSI ionic liquid could be coordinated by DCH18C6 and BOBCalixC6, respectively, and formed the DCH18C6·Sr²⁺ and BOBCalixC6·2Cs⁺ ions, which would be cathodically reduced to Sr- and Cs-amalgam at a mercury film electrode (MFE). In this study, the probability was evaluated if the Sr²⁺ and Cs⁺ cations extracted from the aqueous solutions can be really reduced to respective amalgam.     

离子液体的分类、合成及在氟化工艺中的应用

离子液体不挥发,无污染,无臭味,具有高选择性和催化作用,且易于循环回收利用,作为一种新型的高效绿色溶剂,以其突出的优势已成为绿色化学研究的热点之一。简要介绍了离子液体的分类、合成及其在氟化工艺中的应用。     

Electrodeposition behavior of nickel and nickel-zinc alloys from the zinc chloride-1-ethyl-3-methylimidazolium chloride low temperature molten salt

The electrodeposition of nickel and nickel-zinc alloys was investigated at polycrystalline tungsten electrode in the zinc chloride-1-ethyl-3-methylimidazolium chloride molten salt. Although nickel(II) chloride dissolved easily into the pure chloride-rich 1-ethyl-3-methylimidazolium chloride ionic melt, metallic nickel could not be obtained by electrochemical reduction of this solution. The addition of zinc chloride to this solution shifted the reduction of nickel(II) to more positive potential making the electrodeposition of nickel possible. The electrodeposition of nickel, however, requires an overpotential driven nucleation process. Dense and compact nickel deposits with good adherence could be prepared by controlling the deposition potential. X-ray powder diffraction measurements indicated the presence of crystalline nickel deposits. Non-anomalous electrodeposition of nickel-zinc alloys was achieved through the underpotential deposition of zinc on the deposited nickel at a potential more negative than that of the deposition of nickel. X-ray powder diffraction and energy-dispersive spectrometry measurements of the electrodeposits indicated that the composition and the phase types of the nickel-zinc alloys are dependent on the deposition potential. For the Ni-Zn alloy deposits prepared by underpotential deposition of Zn on Ni, the Zn content in the Ni-Zn was always less than 50 atom%.     

Intensification of zirconium and hafnium separation through the hollow fiber renewal liquid membrane technique using synergistic mixture of TBP and Cyanex-272 as extractant

The novel synergistic mixture of TBP and Cyanex-272 is used as the extractant in the hollow fiber renewal liquid membrane(HFRLM) technique for Zr/Hf separation.The effects of the chemical and operational parameters such as HNO_3 concentration in the donor phase,NH4 F concentration in the acceptor phase,Cyanex-272 and TBP concentration in the liquid membrane phase,the lumen and shell side flow rates,and aqueous/organic volume ratio on the mass transfer and separation performance of HFRLM method were investigated.The obtained results reveal the intensification potential of proposed HFRLM technique for selective extraction of Zr over Hf with separation factor higher than 100.The HFRLM method provides two times higher mass transfer flux in comparison with hollow fiber supported liquid membrane(HFSLM).Also,the HFRLM method shows satisfactory stability for 700 min of continuous operation.The Zr ion transport through the LM phase follows the coupled co-transport mechanism and the diffusion in the renewal layer is recognized as the rate-controlling step in the HFRLM process.Moreover,the Zr mass transfer coefficient and molar flux in the HFRLM method are calculated in the range of 1×10~(-8)to 8.4×10~(-7) m·s~(-1) and 4.9×10~(-6) to 20.1×10~(-6) mol·m~(-2)·s~(-1),respectively.     

离子液体催化酸化油甲酯化工艺及其特性

以酸化油为原料,自制离子液体为催化剂,采用甲酯化方法制备脂肪酸甲酯。通过考察甲醇与脂肪酸物质的量比、离子液体催化剂加入量、反应温度和反应时间对甲酯化反应的影响,最佳反应条件：甲醇与脂肪酸物质的量比9∶1,离子液体催化剂用量为甲醇与游离脂肪酸总质量的25%,反应温度65 ℃,反应时间2.0 h。通过测量原料酸化油与产物的含水量,证明离子液体催化剂具有良好的带水性,有利于甲酯化反应的进行。该方法不仅可降低生产成本,减少环境污染,也能避免油脂资源问题,具有较高经济效益和社会效益。     

The effect of calcium zirconate modifications on the microstructure and functional properties of sodium niobate thin films prepared by chemical solution deposition

Sodium niobate thin films doped with manganese (NN), and NN films modified with 5 or 10 mol % calcium zirconate (CZ) on platinized silicon substrates were prepared by chemical solution deposition. The 250-nm-thick films crystallize in a perovskite phase with fine, equiaxed grains. The NN films exhibit well-shaped ferroelectric loops with a remanent polarization and coercive field of ～10 μC/cm² and ～100 kV/cm, respectively. The modification with CZ strongly influences the ferroelectric response of the films: the remanent polarization progressively decreases to around 2.5 μC/cm². The absence of an anti-ferroelectric response, which has previously been confirmed in bulk NN-CZ ceramics, is attributed to the nanoscale microstructure and residual thermal stresses. All the studied films exhibit a piezoelectric response with the highest piezoelectric d₃₃ coefficient of 35 pm/V at 300 kV/cm bias field for the NN modified films with 5 mol % CZ, making them candidates for lead-free piezoelectric thin-film applications.     

Separation of isopropyl alcohol + isopropyl acetate azeotropic mixture: Selection of ionic liquids as entrainers and vapor-liquid equilibrium validation

Based on the COSMO-SAC model, 1-ethyl-3-methylimidazolium acetate and 1-ethyl-3-methylimidazolium p-toluenesulfonate were selected from 30 ILs as entrainers to investigate the separation of the isopropyl alcohol + isopropyl acetate azeotrope. Two screening indicators, σ-profile and infinite dilution selectivity (S^∞), were adopted as the basis. The isobaric vapor-liquid equilibrium experiments for isopropyl alcohol + isopropyl acetate binary system and isopropyl alcohol + isopropyl acetate + confirmed ILs ternary systems were performed at the pressure of atmospheric pressure. The experimental measurement demonstrated that the adopt ILs enhanced the relative volatility of the above alcohol-ester azeotrope, leading to the elimination of the azeotropic point with a certain amount ILs. Meanwhile, the thermodynamic correlation for two systems containing ILs was explored with the NRTL model, which also reflects the extensive applicability of that by comparing the deviation between experimental and calculated data. And its binary interaction parameters were regressed, which can provide a basis for its simulation process.     

Separation and recovery of the constituents from lignocellulosic biomass by using ionic liquids and acetic acid as co-solvents for mild hydrolysis

Previously, ionic liquids were found to partially dissolve lignocellulosic biomass. Here, it is reported that the biomass itself does not dissolve directly, but that it is hydrolyzed first before the constituents (cellulose, hemicellulose and lignin) dissolve into the ionic liquid. By addition of an acidic catalyst, this hydrolysis step can take place at milder conditions. Acetic acid is chosen as a suitable acidic catalyst, because it is already present in lignocellulosic biomass in the form of acetyl groups on the hemicellulose. Here, it is shown that acetic acid also works as co-solvent, increasing the solubility of the constituents of lignocellulosic biomass in the ionic liquid. The milder conditions for hydrolysis result in a higher degree of utilization of the lignocellulosic biomass, whereby all constituents can be fully recovered and further processed and the ionic liquid can be reused.