Anodic behavior of gold in 1-butyl-3-methylimidazolium methanesulfonate ionic liquid with chloride anion

The anodic behavior of gold has been investigated in presence of chloride and/or water in 1-butyl-3-methylimidazolium methanesulfonate (BMI CH₃SO₃) ionic liquid (IL). The cyclic voltammetry (CVs) in presence of chloride ions shows two waves attributed to the oxidation of the gold electrode which occurs under two steps: the first one is attributed to the electrochemical dissolution of gold into to gold(I), while the second one is attributed to an overlap of the chloride oxidation step as well as the oxidation of Au(I) to Au(III). Furthermore the determination of water and chloride content in IL allowed observing that the passive layer induced by water could be removed under chloride. Thanks to those results we were able to clarify the conditions of gold recovering in this kind of electrolyte.     

Time-dependent properties of epoxy resin with imidazolium ionic liquid

This study investigates creep and viscoelastic behavior of the diglycidyl ether of bisphenol A (DGEBA) epoxy resin and triethylenetetramine (TETA) system containing an imidazolium ionic liquid (IL), the 1-n-butyl-3-methylimidazolium chloride ( C ₄ MImCl ). Different time-dependent analysis methods are studied using data from tensile creep, tensile creep/recovery, and three-point and four-point flexural creep tests of epoxy with 1.0 or 4.0 phr of IL. From the results, the composition containing 1.0 phr of C ₄ MImCl , cured at 60°C, presented greater viscoelasticity and crosslink density compared to compositions cured at 30 and 40°C, which was attributed to higher free volume and higher molecular mobility induced by the presence of the IL. In tensile creep tests using the stepped isostress method (SSM), no important degrading effects were found after the addition of 1.0 phr of IL over long time periods. This composition also showed the best overall performance in flexural SSM creep tests.     

Thermal Performance Analysis of Ionic Liquid-Pretreated Spent Coffee Ground Using Aspen Plus®

Thermal analysis and gasification study of spent coffee ground (SCG) pretreated with ionic liquids (ILs) is presented. Four ILs, namely, 1-butyl-3-methylimidazolium chloride ([Bmim][Cl]), 1-ethyl-3-methylimidazolium chloride ([Emim][Cl]), tributylmethylammonium chloride ([N₁₄₄₄][Cl]), and trihexyltetradecylphosphonium chloride ([P₆₆₆₁₄][Cl]), were investigated. The pretreatment was followed by thermogravimetric analysis. The syngas composition was computed using an equilibrium-based steam-O₂ gasification model developed in Aspen Plus® by varying gasifier temperature and steam/biomass ratio. All ILs reduced the ash content, enhanced the volatility as well as the higher heating value of SCG. IL pretreatment also decreased CO₂ and CH₄ contents showing environmental benefits of using ILs.     

Coal structure change by ionic liquid pretreatment for enhancement of fixed-bed gasification with steam and CO<Subscript>2</Subscript>

An innovative pretreatment of Indonesian low-rank coal (ILRC) by 1-butyl-3-methylimidazolium chloride ([Bmim]Cl) ionic liquid (IL) was conducted. The obtained IL pretreated coal had a loose and porous structure. Fourier transform infrared spectroscopy (FTIR) and Brunauer-Emmett-Teller (BET) analysis showed that pretreated ILRC had a stronger absorption ability and an increased average pore size (from 23.6 to 51.8 nm). Steam-coal gasification was conducted to explore the effect of coal pretreatment. The result showed that 1.63-times more hydrogen was generated from pretreated coal compared to original (i.e., untreated) coal, and carbon conversion (X _c ) increased from 89.03 to 97.25%. During CO₂ coal gasification, IL pretreated coal had a greater CO₂ consumption potential and generated more CO. The chemical exergy of syngas of the pretreated coal gasification was higher than that of the untreated coal gasification with CO₂ at 900 °C. In addition, pretreated coal emitted less CO₂ than untreated coal at 900 °C.     

Preparation of high energy fuel JP-10 by acidity-adjustable chloroaluminate ionic liquid catalyst

The isomerization of endo-tetrahydrodicyclopentadiene (endo-THDCPD) to its exo-isomer (JP-10) has been investigated by using chloroaluminate ionic liquids (ILs) as catalysts. The catalyst activity and selectivity could be optimized by varying the mole fraction of AlCl₃ in the IL. Undesirable by-products derived from side-reactions such as skeletal rearrangement, alkylation, cracking, and dimerization could be minimized by appropriate catalyst design and adjustment of the reaction conditions. The catalyst system was further optimized by selecting 1-butyl-3-methylimidazolium chloride as the basic IL and adding 0.60-0.65 mole fraction of AlCl₃ as the promoter. Using the optimized catalyst system, the isomerization of endo-THDCPD to exo-THDCPD proceeded at a fast rate at 50 °C with 98.9% conversion and 100% selectivity. The catalyst longevity has been demonstrated by recycling the IL several times without a noticeable reduction in catalytic activity.     

Physical and electrochemical properties of lithium-doped 1-butyl-3-methylimidazolium salts

Two well known room temperature ionic liquids (RTILs), 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIm][BF₄]) and 1-butyl-3-methylimidazolium iodide ([BMIm][I]), were synthesized. Their physical properties such as reflective indices, densities, viscosities, heat capacities, and heats of dilution were measured. The overall properties of [BMIm][BF₄] obtained after two-step reactions were superior to those of the IL with a halide anion. The incorporation of lithium ions using lithium tetrafluoroborate (LiBF₄) in each IL was carried out and ionic conductivities as a function of temperature and Li ion concentration were investigated. The isothermal conductivity graph showed a parabolic curve shape suggesting that the maximum values exist at a specific concentration condition while they continuously increased as the temperature increased. The conductivities reached as high as 10⁻³ S·cm⁻¹.     

Rapid Carbonation for Calcite from a Solid-Liquid-Gas System with an Imidazolium-Based Ionic Liquid

Aqueous carbonation of Ca(OH)₂ is a complex process that produces calcite with scalenohedral calcite phases and characterized by inadequate carbonate species for effective carbonation due to the poor dissolution of CO₂ in water. Consequently, we report a solid-liquid-gas carbonation system with an ionic liquid (IL), 1-butyl-3-methylimidazolium bromide, in view of enhancing the reaction of CO₂ with Ca(OH)₂. The use of the IL increased the solubility of CO₂ in the aqueous environment and enhanced the transport of the reactive species (Ca²⁺ and CO₃²⁻) and products. The presence of the IL also avoided the formation of the CaCO₃ protective and passivation layer and ensured high carbonation yields, as well as the production of stoichiometric rhombohedral calcite phases in a short time.     

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).     

Electrochemical dissolution of metallic platinum in ionic liquids

The electrochemical dissolution of Pt in several ionic liquids (IL’s) was studied. Different IL’s were tested assessing their potential to dissolve Pt. Dissolution rate and current efficiency were evaluated. The main focus was on Cl containing IL’s: first generation, eutectic based IL’s and second generation IL’s with discrete anions. Pt dissolution only occurred in type 1 eutectic-based IL’s with a max. dissolution rate of 192.2 g m^?2 h^?1 and a max. current efficiency of 99 % for the ZnCl₂-1-ethyl-3-methylimidazolium chloride IL, and 9.090 g m^?2 h^?1 and 96 % for the 1:1 ZnCl₂–choline chloride ionic liquid. The dissolution occurred via the formation of [PtCl _x ] ^y? complexes. To form these complexes, addition of a metal chloride was necessary. Furthermore, an IL with an electrochemical window of 1.5 V, preferably 2.0 V is required to achieve Pt dissolution. The added metal salt needed to have a higher decomposition potential than 1.5 V or should be a Pt salt.     

Reactivity of the raw materials and their effects on the structure and properties of rigid polyurethane foams

Formulations for rigid polyurethane foams (RPUFs) based on crude 4,4′‐diphenylmethane diisocyanate, polyether polyol, triethylenediamine, 1,4‐butane diol, poly(siloxane ether), methylene chloride, and water were studied. The stoichiometric ratios of various foam ingredients and their effects on physical properties such as the cream time, gel time, tack‐free time, and density of the RPUF samples were studied. The results indicated that the rate of RPUF formation increased with the catalyst (triethylenediamine and tin) and water content. The density of the RPUF samples blown with water, methylene chloride, and a mixture of water and methylene chloride decreased from 240.1 to 33.4 kg/m³ with an increase in the blowing agent contents. However, the RPUF density increased with increasing contents of 1,4‐butane diol. The cell morphology and thermal properties of the RPUF samples were investigated with scanning electron microscopy, thermogravimetric analysis, derivative thermogravimetry, and differential thermal analysis. Scanning electron microscopy results revealed an average increase in the cell size of the RPUF samples from 162 to 278 μm with increased water content. A thermal behavior study indicated that the RPUF samples decomposed in nitrogen and degraded in air through two and three weight‐loss stages, respectively. Foam pyrolysis in nitrogen and combustion in air led to 15 and 0% char residue, respectively. The results indicated that the thermal stability of the RPUFs was better in nitrogen than in an air atmosphere. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Alkoxyl side-chain effects of acidic ionic liquids catalysts for the esterification of n-butyl butyrate

Three kinds of alkoxy group-functionalized acidic ionic liquids (ILs) are reported in this work, namely, 1-(methoxyethyl)-3-methylimidazolium hydrogen sulphate [MOE-MIM]HSO₄, 1-(ethyoxyethyl)-3-methylimidazolium hydrogen sulphate [EOE-MIM]HSO₄, and 1-(propyoxyethyl)-3-methylimidazolium hydrogen sulphate [POE-MIM]HSO₄. The short side chain on the cation of [MOE-MIM]HSO₄ decreases the solubility of the IL in butanol and butyric acid and facilitates the separation of the IL from a reaction medium. The yield of butyl butyrate is up to 99.5%. After 10 rounds of recycling, the catalytic performance of [MOE-MIM]HSO₄ shows no significant changes.     

Critical properties and acentric factors of ionic liquids

Since most ionic liquids (ILs) decompose before reaching their critical state, the experimental measurement of their critical properties are not possible. In this study, the critical temperatures, critical pressures and acentric factors of ten commonly investigated ILs were determined by making an optimum fit of the calculated vapor-liquid equilibrium data of binary mixtures of CO₂+IL to the experimental values found in literature. For this purpose, the Peng-Robinson equation of state (PR EoS) and the differential evolution optimization method were used. The ILs considered were 1-ethyl-3-methylimidazolium hexafluorophosphate ([emim][PF₆]), 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl) imide ([emim][Tf₂N]), 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim][BF₄]), 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF₆]), 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl) imide ([bmim][Tf₂N]), 1-hexyl-3-methylimidazolium tetrafluoroborate ([hmim][BF₄]), 1-hexyl-3-methylimidazolium hexafluorophosphate ([hmim][PF₆]), 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl) imide ([hmim][Tf₂N]), 1-octyl-3-methylimidazolium tetrafluoroborate ([omim][BF₄]) and 1-octyl-3-methylimidazolium hexafluorophosphate ([omim][PF₆]). To evaluate the ability of the determined parameters in predicting the phase behavior of systems other than the systems that were used for parameter optimization, both sets of parameters obtained in this work and that of Valderrama et al. were used to predict bubble-point pressures of CHF₃+[bmim][PF₆] (by using the PR EoS and the Soave-Redlich-Kwong equation of state. The bubble-point pressures of CO₂+IL systems optimized in this study by the PR EoS were also determined using the Soave-Redlich-Kwong equation of state (SRK EoS). In addition, liquid densities of pure ILs were predicted using a generalized correlation proposed by Valderrama and Abu-Shark. In all cases, the various predicted properties of these ten ILs, were in better agreement with the experimental data, using the critical properties and acentric factor obtained in this study, compared to the values suggested by Valderrama et al.     

Study on Dissolution and Regeneration of Poplar Wood in Imidazolium-Based Ionic Liquids

Abstract

We tested dissolution and regeneration of poplar wood using 1-butyl-3-methylimidazolium chloride ([C₄mim]Cl) and 1-butyl-3-methylimidazolium acetate ([C₄mim]OAc). When 5wt% of poplar sawdust in [C₄mim]OAc was stirred at 130°C, 96wt% of added poplar was dissolved in [C₄mim]OAc, whereas 25.3wt% of poplar dissolved in [C₄mim]Cl at the same reaction condition. Fourier transform infrared spectroscopy (FT-IR) and lignin content analysis revealed that poplar was partially delignified during the dissolution and regeneration processes. X-ray diffraction (XRD), thermal gravimetric analysis (TGA), and microscopy were used to characterize raw poplar sawdust, undissolved poplar, and regenerated wood from the poplar-ionic liquid solution. The direct acetylation of poplar-[C₄mim]OAc solution using acetyl chloride was also performed in the absence of any organic solvent. FT-IR analysis of the resulting wood sample revealed the formation of partially delignified acetylated-poplar.     

Erratum to: Electrochemical dissolution of metallic platinum in ionic liquids

The electrochemical dissolution of Pt in several ionic liquids (ILs) was studied. Different ILs were tested assessing their potential to dissolve Pt. Dissolution rate and current efficiency were evaluated. The main focus was on Cl containing ILs: first generation, eutectic-based ILs and second generation ILs with discrete anions. Pt dissolution only occurred in type 1 eutectic-based ILs with a max. dissolution rate of 192.2 g m^?2 h^?1 and a max. current efficiency of 99 % for the ZnCl₂–1-ethyl-3-methylimidazolium chloride IL, and 9.090 g m^?2 h^?1 and 96 % for the 1:1 ZnCl₂–choline chloride IL. The dissolution occurred through the formation of [PtCl_x]^y? complexes. To form these complexes, addition of a metal chloride was necessary. Furthermore, an IL with an electrochemical window of 1.5 V, preferably 2.0 V was required to achieve Pt dissolution. The added metal salt needed to have a higher decomposition potential than 1.5 V or should be a Pt salt.     

Rheological properties of cellulose/ionic liquid/dimethylsulfoxide (DMSO) solutions

Rheological properties of cellulose dissolved in two ionic liquids (ILs), 1-allyl-3-methylimidazolium chloride (AmimCl) and 1-butyl-3-methylimidazolium chloride (BmimCl), with co-solvent dimethylsulfoxide (DMSO), are studied in the concentration range of cellulose from 0.070 to 6.0 wt%. The viscosities of ILs are exponentially decreased by adding DMSO in the concentration range of 0–100 wt%. The co-solvent DMSO decreases the monomer friction coefficient in cellulose solutions and has no significant change for the entanglement state of cellulose, thus results in the reduced solution viscosity, shortened relaxation time and unchanged moduli of the cross-over point. For cellulose solutions, dilute regime, semidilute unentangled regime and semidilute entangled regime were determined by steady shear experiments. In semidilute entangled regime, the specific viscosities η_sp, relaxation time τ, and plateau modulus G_N, exhibit concentration dependences as η_sp ～ C^4.4, τ ～ C^2.2, andG_N ～ C^1.9, respectively, in AmimCl-DMSO (80/20 w/w); and η_sp ～ C^4.3, τ ～ C^2.0, and G_N ～ C^2.1, respectively, in BmimCl–DMSO (80/20 w/w). Therefore, the rheological properties of cellulose/IL/DMSO solutions are approximately of IL-independence in this study. The dependence of η_sp upon cellulose concentration shows that the IL–DMSO mixture is more like a θ solvent for cellulose, and the thermodynamic properties of IL–DMSO mixtures are similar with those of ILs for cellulose at 25 °C. The conformation of cellulose in ILs would not be changed with the addition of DMSO not only in the dilute regime but also in the entanglement regime.     

Synthesis of water-soluble cellulose esters applying carboxylic acid imidazolides

Water-soluble, non-ionic cellulose esters with a degree of substitution in the range from 0.11 to 3.0 were synthesized homogeneously using ionic liquids (1-butyl-3-methylimidazolium chloride, 1-ethyl-3-methylimidazolium chloride, and 1-allyl-3-methylimidazolium chloride) as reaction medium. Highly substituted 3,6,9-trioxadecanoic acid esters and 3,6-dioxaheptanoic acid esters of cellulose were obtained via the activation of the carboxylic acids with N,N’-carbonyldiimidazole. The products were characterized by the means of FTIR-, ¹H- and ¹³C NMR spectroscopy.     

Butanol alcoholysis reaction of polyethylene terephthalate using acidic ionic liquid as catalyst

The alcoholysis reaction of polyethylene terephthalate (PET) and n‐butanol to produce dibutyl terephthalate (DBTP) and ethylene glycol (EG) was investigated in the presence of a Brönsted–Lewis acidic ionic liquid (IL). It was found that a synergetic effect of Brönsted and Lewis acid sites enhanced the IL catalytic performance, and (3‐sulfonic acid) propyltriethylammonium chlorozincinate [HO₃S‐(CH₂)₃‐NEt₃]Cl‐ZnCl₂ (molar fraction of ZnCl₂ (x) was 0.67) was a good catalyst for the reaction. The conversion of PET was 100%, and the yields of DBTP and EG were 95.3% and 95.7% at 205°C for 8 h, respectively. The reusability of IL was good and after it was used seven times, PET conversion and the yields of DBTP and EG did not significantly decrease. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 1840–1844, 2013     

The effects of Li salts on the performance of a polymer actuator based on single-walled carbon nanotube-ionic liquid gel

The effects of Li salts (Lithium tetrafluoroborate (Li[BF₄]) and Lithium bis(trifluoromethanesulfonyl)imide (Li[TFSI])) on the electrochemical and electromechanical properties of an actuator using a polymer-supported single-walled carbon nanotube (SWCNT)-ionic liquid (IL) gel electrode were investigated. The ionic conductivities of the gel electrolyte layers with molar ratios of Li[BF₄]/1-ethlyl-3-methylimidazolium tetrafluoroborate (EMI[BF₄]) = 0.1 and 0.5, and Li[TFSI]/1-ethlyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide (EMI[TFSI]) = 0.1 and 0.3 were higher than those containing only EMI[BF₄] and only EMI[TFSI], respectively. We found a large capacitance value 65-96 F/g at a slow sweep rate 1 mV s⁻¹. The actuator containing Li salt/IL performed much better than that containing only IL. It is considered that the higher ionic conductivity of the gel electrolyte layer containing Li salt/IL produces the quick response actuator, and that the large capacitance gives a large generated strain.     

Examining the Role of Effluent Organic Matter Components on the Decomposition of Ozone and Formation of Hydroxyl Radicals in Wastewater

The impact of wastewater derived effluent organic matter (EfOM) on the decomposition of ozone and formation of hydroxyl radicals (HO^●) was evaluated for four wastewaters (sites A, B, C1 and C2). The reactivity of EfOM was assessed by fractionation into four apparent molecular weight (AMW) fractions (<10 kDa, <5 kDa, <3 kDa, and <1 kDa). The R_CT, defined as the ratio of HO^● exposure to ozone exposure (∫HO^●dt?/?∫O₃dt), was measured for all fractions and bulk waters (at times greater than 5 seconds), with an initial ozone dose equal to the total carbon concentration of EfOM (ozone:DOC ratio of 1). The R_CT of all the samples and ozone first-order decay rates of two of the waters increased significantly (95% confidence) from the bulk sample to the <10 kDa fraction, and decreased with AMW. This indicates that the intrinsic capacity of different molecular weight fractions of the EfOM have different reactivity with ozone.     

Synthesis of Glycerol Triacetate Using a Brønsted–Lewis Acidic Ionic Liquid as the Catalyst

Brønsted–Lewis acidic ionic liquids (IL) were used in the esterification of glycerol and acetic acid to produce glycerol triacetate. The results show that the IL (3–sulfonic acid)–propyltriethylammonium chloroironinate [HO₃S–(CH₂)₃–NEt₃]Cl–[FeCl₃]_x (molar fraction of FeCl₃, x = 0.67) was an efficient catalyst for the esterification reaction. The yield of glycerol triacetate and its content were greater than 98 % when reacted under reflux for 4 h. It was observed that a synergistic effect of Brønsted and Lewis acid sites enhanced the catalytic performance of IL. The reusability of IL was good. After six reaction cycles, the glycerol triacetate yield and concentration were still greater than 98 %. Likewise, the Brønsted–Lewis acidic IL was an efficient catalyst for esterification reactions of high boiling points alcohols with acetic acid.