Recovery Of Ionic Liquid Research Articles

Simulated Moving Bed Chromatography: Separation and Recovery of Sugars and Ionic Liquid from Biomass Hydrolysates

Separation from bed, not board: Simulated moving bed chromatography, a continuous separation method, enables the nearly quantitative recovery of sugar products and ionic liquid solvent from chemical hydrolysates of biomass. The ensuing sugars support microbial growth, and the residual lignin from the process is intact.

Microwave Irradiation Pyrolysis of Rice Straw in Ionic Liquid ([Emim]Br)

The pyrolysis reaction of rice straw under microwave irradiation in bromide 1-ethyl-3-methyl imidazole ([Emim]Br) ionic liquid (IL) was investigated in this work. The effects of reaction temperature, mass ratio of IL to straw, reaction time, and microwave irradiation power on the yield of bio-oil were considered. An orthogonal experimental method was adopted to obtain the optimal technological conditions for pyrolysis: a reaction temperature of 160 °C, a mass ratio of IL to straw of 2:1, a reaction time of 15 min, and a microwave irradiation power of 700 W. The yield of bio-oil reached 28.2% at optimum conditions. The percent recovery of IL ranged from 84% to 87%. The recycled IL could be reused as straw pyrolysis solvent and did not affect the bio-oil yield because its structure was not damaged after being used in pyrolysis as a solvent.

Influence of Aprotic Solvents on the Phase Behavior of Ionic Liquid Based Aqueous Biphasic Systems

Although aprotic solvents (ASs) have been largely explored as cosolvents of ionic liquids (ILs) for biomass resources pretreatment, the separation and recovery of ILs along with ASs were seldom inv...

Ethylacetoacetate tagged basic imidazolium salt: multi-task in CuI nanoparticle catalyzed amination of aryl halides

Copper catalyzed reactions suffer from harsh conditions of high temperature, high pressure, over-stoichiometric amount of copper reagents and use of expensive ligands. In an attempt to develop a mild, efficient and reusable system for copper catalyzed reactions, ethylacetoacetate was doped into ionic liquid (IL) by tagging it with imidazolium cation stabilized by a counter hydroxide or acetate anion (4a and 4b). The novel ligand-anchored ILs demonstrated high efficiency in generation and stabilization of uniformly dispersed Cu(I)I nanoparticles with particle size in range 9–12 nm. Further, the catalytic system provided an efficient route to amination of aryl iodides, bromides and the less reactive chlorides under mild conditions with very low catalyst loading of only 2 mol % to yield primary aryl amines selectively. Furthermore, the reaction allowed easy isolation of products with recovery of ionic liquid containing an intact built-in ligand and base combination for further reuse.

Highly efficient enzymatic synthesis of Galβ-(1→3)-GalNAc and Galβ-(1→3)-GlcNAc in ionic liquids

Ionic liquids (ILs) have emerged as an alternative to conventional organic media due to their high thermal and chemical stability, negligible vapour pressure, non-flammability and easy recycling. In this context, this work assesses the catalytic activity of a β-galactosidase from Bacillus circulans ATCC 31382 (β-Gal-3-NTag) in the synthesis of β-(1→3)-galactosides using different ILs. A noticeably increase in activity, retaining total regioselectivity was found in the synthetic behaviour of B. circulans β-galactosidase in ILs as co-solvents and using a 1:5 molar ratio of donor (pNP-β-Gal):acceptor (GlcNAc or GalNac). Yields up to 97% of β-(1→3) with different ILs were found. These reactions take place without noticeable hydrolytic activity and with total regioselectivity, representing a considerable improvement over the use of aqueous buffer or conventional organic solvents. Furthermore, reaction scaling up and IL recovery and recycling are feasible without losing catalytic action. Molecular modelling studies performed predict a three-dimensional interaction at the active centre between the acceptor and the water–IL mixture, which could explain the results obtained.

Production and extraction of sugars from switchgrass hydrolyzed in ionic liquids

BackgroundThe use of Ionic liquids (ILs) as biomass solvents is considered to be an attractive alternative for the pretreatment of lignocellulosic biomass. Acid catalysts have been used previously to hydrolyze polysaccharides into fermentable sugars during IL pretreatment. This could potentially provide a means of liberating fermentable sugars from biomass without the use of costly enzymes. However, the separation of the sugars from the aqueous IL and recovery of IL is challenging and imperative to make this process viable.ResultsAqueous alkaline solutions are used to induce the formation of a biphasic system to recover sugars produced from the acid catalyzed hydrolysis of switchgrass in imidazolium-based ILs. The amount of sugar produced from this process was proportional to the extent of biomass solubilized. Pretreatment at high temperatures (e.g., 160°C, 1.5 h) was more effective in producing glucose. Sugar extraction into the alkali phase was dependent on both the amount of sugar produced by acidolysis and the alkali concentration in the aqueous extractant phase. Maximum yields of 53% glucose and 88% xylose are recovered in the alkali phase, based on the amounts present in the initial biomass. The partition coefficients of glucose and xylose between the IL and alkali phases can be accurately predicted using molecular dynamics simulations.ConclusionsThis biphasic system may enable the facile recycling of IL and rapid recovery of the sugars, and provides an alternative route to the production of monomeric sugars from biomass that eliminates the need for enzymatic saccharification and also reduces the amount of water required.

Fabrication and characterization of electro-active cellulose films regenerated by using 1-butyl-3-methylimidazolium chloride ionic liquid

This article reports dissolution, regeneration, and characterization of cellulose using an ionic liquid, namely 1-butyl-3-methylimidazolium chloride (BMIMCl). During dissolving process, BMIMCl takes much less time to dissolve cellulose with high degree of polymerization (DP = 4500) than other solvent system, lithium chloride/ N,N-dimethylacetamide (LiCl/DMAc). Regenerated cellulose film from BMIMCl–cellulose solution is characterized by viscosity, thermo gravimetric analyzer, X-ray diffraction, pull test, and transmittance test. Compared with LiCl/DMAc–cellulose, BMIMCl–cellulose solution has lower viscosity and its film has lower Young's modulus and yield strength. From thermo gravimetric analyzer and X-ray diffraction experiment, BMIMCl–cellulose film has impurity and X-ray diffraction pattern similar with those of LiCl/DMAc–cellulose film. BMIMCl–cellulose film exhibits higher transmittance. The ionic liquid recovery test verifies that BMIMCl is highly recoverable with 99%, which proves that BMIMCl is a green solvent. Through the bending displacement test, the BMIMCl–cellulose film shows a good actuation behavior of electro-active paper.

Novel pre-treatment and fractionation method for lignocellulosic biomass using ionic liquids

An efficient lignocellulosic biomass pre-treatment is a crucial step for the valorization of these kind of raw materials. Lignocellulosic biomass is a potentially valuable resource for transformation into biofuels and bio-based products. The use of ionic liquids as media for the biomass pre-treatment is an alternative method that follows the green chemistry concept. This work proposes a new methodology for wheat straw pre-treatment with the ionic liquid (IL) 1-ethyl-3-methylimidazolium acetate ([emim][OAc]), which allowed the production of cellulose, hemicellulose and lignin-rich fractions in a rapid and simple three-step fractionation process. Various temperatures (80–140 °C) and processing times (2–18 h) of the pre-treatment were studied. The quantitative and qualitative analysis of each lignocellulosic biomass fraction was determined by FTIR measurements. The glucan content in recovered cellulose-rich fractions was investigated by enzymatic hydrolysis. The cellulose recovery dependence on the pre-treatment conditions was ascertained through regression analysis. The optimal result for the recovery of the cellulose-rich fraction was obtained at 140 °C during 6 h achieving 37.1% (w/w) of the initial biomass loading. For the same conditions, optimal results were also produced regarding the amount of glucan present (81.1% w/wbiomass) in cellulose-rich fractions, the carbohydrate enrichment in the hemicellulose fraction (96% wt) and the purity of lignin (97% wt). The recovery of IL was performed after each pre-treatment and the obtained yields were up to 86% (w/w). The recovered ILs were analyzed by 13C and 1H NMR. The presence of value-added phenolic compounds in the recovered ILs was analyzed by capillary electrophoresis. Vanillin and its derivatives, as well as other lignin-based products, were identified.

Recovery of Ionic Liquids from Wastewater by Nanofiltration

In this study, the possibility to recover ionic liquids from their respective wastewater by nanofiltration was tested in two case studies. The experiments were performed using a commercial dead-end stirred cell and/or a cross-flow cell especially developed for this purpose. Hydrophilic ionic liquids are being presently used for the dissolution of cellulose and its further regeneration by water addition. Wastewater containing a mixture of 1-butyl-3-methylimidazolium chloride (IM14 Cl) and 1-butyl-3-methylimidazolium acetate (IM14 1COO) was treated by nanofiltration and the ionic liquids were recovered as an aqueous solution which is also almost free of undesired by-products. On the contrary, hydrophobic ionic liquids are commonly used in biphasic systems to perform either enzymatic or whole-cell biotransformations. Wastewater containing hydrophobic ionic liquids derived from the conversion of 2-octanone to 2-octanol was also tested, and the ionic liquids used can be recovered as a separate phase by concentrating them beyond the solubility limit. The effect of other wastewater components on the recovery was also investigated with the ionic liquid 1-hexyl-3-methylimidazolium bis (trifluoromethylsulfonyl) amide, IM16 (CF3SO2)2N. Furthermore, using model solutions of 1-hexyl-1-methylpyrrolidinium bis (trifluoromethylsulfonyl) amide, Pyr16 (CF3SO2)2N, it could be evidenced that the formation of a new phase of ionic liquid during the concentration process follows a nucleation-growth mechanism. In this case, up to 69% of the ionic liquid originally present in the feed was separated. Additionally, the effective recovery rate was duplicated up to 33% by using a coalescence filter. Some suggestions to increase both theoretical and effective recovery rates are also discussed.

Recovery of Ionic Liquids with Aqueous Two‐Phase Systems Induced by Carbon Dioxide

Recovery is a very important factor for the industrial application of ionic liquids (ILs). In this work, a novel method is presented for the recovery of ILs by using carbon dioxide (CO₂-induced formation of aqueous two-phase systems (ATPSs). It was found that, in the presence of amines, introduction of CO₂ into aqueous IL solutions leads to the formation of ATPSs at 25 °C and atmospheric pressure, in which the upper phase is ammonium-salt-rich and the lower phase is IL-rich. Thus, the ILs in aqueous solutions can be significantly enriched, and the amines can be regenerated by heating and bubbling Ar or N₂ in the salt-rich phase. To better understand the recovery of ILs, the phase diagrams of the ATPSs were measured at 25 °C, and the effects of the molecular structure of the ILs and the amines and temperature of the systems on the recovery efficiency of the ILs were investigated. It was shown that the single-step recovery efficiency of the ILs could be as high as 99 % in the presence of primary or secondary amines. Therefore, this new method could potentially be sustainable, efficient, and attractive to industry.

The Application of Nanofiltration Technology in Recovery of Ionic Liquids from Spinning Wastewater

In this paper, the effects of the concentration, temperature, and run-time of ionic liquids solution, on the rejection capacity of home-made hollow fiber composite nanofiltration membrane were studied. Then the nanofiltration membrane was used to the recover ionic liquids by concentrating spinning wastewater. The results shows that: The rejection rate of the composite nanofiltration membranes and its water fluxes lightly down with the concentration of ionic liquids increase; with running-time and temperature of ionic liquid solution increase, the rejection rate of the composite nanofiltration membranes decreases, but its water flux increases; the nanofiltration membrane can be use for recovering ionic liquid from the spinning wastewater and get very good recovery effects.

Dissolution of lignocellulose in ionic liquids and its recovery by nanofiltration membrane

The dissolution kinetics of lignocellulose from a suitable source of north east India has been studied in ionic liquid at room temperature. The measured profiles of time versus concentration of lignocelluloses were interpreted from a kinetic model and the rate constant was obtained by regression analysis of the data and the values of the rate constant was found to be 54.79×10−8cm/s. The dissolution profiles indicate clear prospect of separating the constituents by suitable methods. Recovery of ionic liquid has also been studied by membrane technology using commercial nanofiltration membrane. The effect of applied pressure gradient (ΔP) and concentration of lignocellulose on the rejection and membrane fouling was studied over a range of pressure and concentration of 2–5bar and 0.01–0.03mmoleL−1 respectively. The solution flux increases with pressure in the pressure range studied indicate the effect of concentration polarization is not significant in this range. The permeation phenomenon has been analyzed on the basis of pore flow transport model and is well fitted with the experimental values.

Simultaneous design of ionic liquid entrainers and energy efficient azeotropic separation processes

A methodology and tool set for the simultaneous design of ionic liquid entrainers and azeotropic separation processes is presented. By adjusting the cation, anion, and alkyl chain length on the cation, the properties of the ionic liquid can be adjusted to design an entrainer for a given azeotropic mixture. Several group contribution property models available in literature have been used along with a newly developed group contribution solubility parameter model and UNIFAC model for ionic liquids (UNIFAC-IL). For a given azeotropic mixture, an ionic liquid is designed using a computer-aided molecular design (CAMD) method and the UNIFAC-IL model is used to screen design candidates based on minimum ionic liquid concentration needed to break the azeotrope. Once the ionic liquid has been designed, the extractive distillation column for the azeotropic mixture is designed using the driving force method with a new proposed feed stage scaling to minimize energy inputs. Along with the distillation column, an ionic liquid recovery stage is designed and simulations are used to determine the overall heat duty for the entire process for the best ionic liquid candidates. Use of a designed ionic liquid reduces material and energy requirements when compared to an ionic liquid known to experimentally break a given azeotrope but not designed using CAMD methods. The acetone–methanol and ethanol–water azeotropes are provided as examples.

Developing criteria for the recovery of ionic liquids from aqueous phase by adsorption with activated carbon

Adsorption with activated carbons (ACs) has been recently reported as an affordable environmental application to remove and recover ionic liquids (ILs) from water streams. In this work, an extensive analysis of the separation of imidazolium-based ILs from aqueous solution, based on adsorption equilibrium experiments at 308K, has been performed. The study includes five commercial and four modified ACs, with a wide variety of structural and chemical properties, a carbon black and also two inorganic adsorbents. The materials tested were characterized by several techniques in order to establish the role of the porous structure and chemical surface on their adsorption capacities. We found that the microporous ACs with low concentration of polar groups in their surface are the best candidates for adsorption of hydrophobic ILs, reaching uptakes of up to 1g of IL per gram of adsorbent. The influence of both cation and anion on the adsorption process was analyzed from the adsorption isotherms of 27 different ILs. The dependence of the adsorption uptake with the chemical structure of the ILs was explained by mean of the quantum-chemical COSMO-RS model, which provides information of the intermolecular interactions between the IL adsorbate and the AC adsorbent. As a result, some insight into the adsorbent modifications needed for improving of the adsorption of specific ILs were achieved and successfully applied to the adsorption of hydrophilic ILs by oxidized ACs.In addition, a procedure for regenerating the exhausted adsorbent and recovering the IL by acetone extraction was validated upon successive adsorption–desorption cycles with two commercial ACs. Finally, the acetone was separated by atmospheric distillation, being the IL recovered without structural modification.

Extracting keratin from chicken feathers by using a hydrophobic ionic liquid

Keratin was extracted from chicken feathers by using a hydrophobic ionic liquid (IL), 1-hydroxyethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)amide ([HOEMIm][NTf2]). Extracted keratin has good solubility in water while the ionic liquid is immiscible with water, and therefore the extracted keratin could be easily separated from the reaction system by water. The effects of ionic liquid, NaHSO3, reaction temperature and time were investigated and extracting conditions were optimized. The maximum yield of keratin was up to about 21% with mass ratio of feathers to NaHSO31:1 and mass ratio of feathers to ionic liquid 1:40 at 80°C for 4h. Moreover, there was no obvious loss in the yield after ionic liquid was reused for five batches under optimized conditions. In addition, the recovery of ionic liquid was about 95% each time. The results indicated that [HOEMIm][NTf2] was very efficient as catalyst and solvent for dissolving feathers and could be easily recovered due to its hydrophobicity.

Improved recovery of ionic liquids from contaminated aqueous streams using aluminium-based salts

The number of applications involving ionic liquids has dramatically increased in the past few years, and their production and use in a large scale will inevitably lead to their dispersion into water streams (either by wastewater disposal or accidental leakage). Studies on the removal and recovery of ionic liquids from wastewater streams are therefore of crucial importance, yet particularly scarce. In this work, the use of aluminium salts is proposed to concentrate and remove ionic liquids from aqueous solutions. Two aluminium-based salts (Al2(SO4)3 and AlK(SO4)2·12H2O) were used to treat various aqueous solutions of ionic liquids containing imidazolium-, pyridinium- and phosphonium-based fluids. The gathered results show the enhanced ability of these salts to remove and recover ionic liquids from aqueous media. The minimum recovery efficiency achieved was 96%, whereas for a large array of systems recoveries of circa 100% of ionic liquid were attained. The residual concentrations of ionic liquids in water range from 0.01 to 6 wt%. The results reported disclose a novel promising technique for the recovery and treatment of aqueous effluents contaminated with ionic liquids by using salts commonly employed in water treatment processes, allowing thus its easy scale-up and adaptation to new processes involving ionic liquids.

REMOVED: Recovery of Ionic Liquids from Chemical Extraction Process of Lignocelluloses

REMOVED: Recovery of Ionic Liquids from Chemical Extraction Process of Lignocelluloses

Recovery of ionic liquid and sugars from hydrolyzed biomass using ion exclusion simulated moving bed chromatography

Efficient recovery of ionic liquid (IL) from aqueous mixture of ILs and sugars (which derived from enzymatic or chemical catalyzed hydrolysis of ILs-pretreated biomass) is a major drawback for commercialization of biofuel and platform chemicals production from biomass utilized ILs as pretreatment solvent. In this study, simulated moving bed (SMB) chromatography equipped with ion exclusion column (containing [Emim]+ cation) was investigated to separate sugars (glucose and xylose) which are the main products from biomass hydrolysate and 1-Ethyl-3-methylimidazolium acetate (EmimAc) which is the ILs used for biomass pretreatment. A four-zone SMB system with a configuration of 2-2-2-2 (2 ion exclusion columns in each zone) was used to recover glucose, xylose and EmimAc from their aqueous mixture with yield of 71.38, 99.37 and 98.92%, respectively. Moreover, the optimization of SMB zone configuration by simulation results in a complete recovery of ILs. This result indicates that for the first time, ion exclusion SMB chromatography could be used for complete recovery of ILs from aqueous sugar mixture.

Recovery of ionic liquids from dilute aqueous solutions by electrodialysis

Ionic liquid/s (IL/ILs) are ideal solvents for many separation processes, such as cellulose dissolution, extraction of heavy metal ions and coal liquefaction residues, etc. During the above processes, ILs would inevitably remain in effluents. Due to their high costs and potential detrimental impacts on environment, it is extremely important to recycle ILs from dilute aqueous solutions. Electrodialysis (ED) was used for primary separation and recycling ILs. In order to evaluate the performance of ED process, the effects of initial concentration, applied voltage and initial volume of the dilute solutions on the overall current efficiency (η), recovery ratio (R) and concentration ratio (ω) were investigated. Among these experimental results, the highest recovery ratio could reach 85.2% and the highest overall current efficiency could reach 80.9%. The ED energy consumption is also discussed and the highest specific energy consumption (R e) could reach about 1350 g/kW h. The effects of IL cation and anion sizes on concentrating process are also evaluated. The experimental results indicate that ED is an effective method to concentrate IL aqueous solutions.

Thinking in Terms of Structure-Activity-Relationships (T-SAR): A Tool to Better Understand Nanofiltration Membranes.

A frontier to be conquered in the field of membrane technology is related to the very limited scientific base for the rational and task-specific design of membranes. This is especially true for nanofiltration membranes with properties that are based on several solute-membrane interaction mechanisms. “Thinking in terms of Structure-Activity-Relationships” (T-SAR) is a methodology which applies a systematic analysis of a chemical entity based on its structural formula. However, the analysis become more complex with increasing size of the molecules considered. In this study, T-SAR was combined with classical membrane characterization methods, resulting in a new methodology which allowed us not only to explain membrane characteristics, but also provides evidence for the importance of the chemical structure for separation performance. We demonstrate an application of the combined approach and its potential to discover stereochemistry, molecular interaction potentials, and reactivity of two FilmTec nanofiltration membranes (NF-90 and NF-270). Based on these results, it was possible to predict both properties and performance in the recovery of hydrophobic ionic liquids from aqueous solution.