Recovery Of Ionic Liquid Research Articles

Techno‐economic analysis of cellulose dissolving ionic liquid pretreatment of lignocellulosic biomass for fermentable sugars production

AbstractPretreatment of biomass is essential to produce fermentable sugars, which can be further transformed into biofuels. Most of the common pretreatment methods, including sulfuric acid pretreatment, lead to low sugar yields and high microbial inhibitors formation, and require an additional detoxification step prior to fermentation. Ionic liquid (IL) pretreatment has the potential to reduce or eliminate these problems, and, thus, recently, has gained significant attention as an alternative pretreatment technology. However, before commercial deployment, IL pretreatment requires a thorough assessment of its techno‐economic feasibilities and bottlenecks. Thus, the main objective of this study was to assess the techno‐economic feasibility of a commercial‐scale IL pretreatment for a 113 million liter/year (30 million gal/year) cellulosic biorefinery and identify operational targets for process improvement. 1‐ethyl‐3‐methylimidazolium acetate IL was used for analyses, which is one of the mostly investigated ILs and is currently best at dissolving the lignocellulosic biomass. Corn stover, poplar, and switchgrass were used as the model feedstock. Input data were obtained from recent literatures on IL pretreatment of these feedstocks. Estimated sugar production costs ($/kg) from corn stover, switchgrass and poplar were 2.7, 3.2, and 3.0, respectively. IL recovery was identified to be the most sensitive parameter followed by IL cost and heat recovery. Furthermore, for IL pretreatment to be economically competitive with sulfuric acid pretreatment, >97% IL recovery, ≤$1/kg IL cost, and >90% waste heat recovery are necessary, all of which are very optimistic considerations at the present state of technology, thus requires further research and development efforts. © 2015 Society of Chemical Industry and John Wiley & Sons, Ltd

Ionic liquid-mediated solid acid saccharification of sago waste: Kinetic, ionic liquid recovery and solid acid catalyst reusability study

Dissolved carbohydrate obtained from 1-butyl-3-methylimidazolium chloride ([BMIM]Cl) pretreated sago waste was saccharified by Amberlyst 15 (A15) to study the kinetics of the ionic liquid-mediated solid acid saccharification of the lignocellulosic biomass. Besides the kinetics of both reducing sugars production and reducing sugars degradation reactions, emphasis was given to the recovery and reusability of the ionic liquid and solid acid catalyst. The hydrolysis reaction follows a first order sugars production-first order sugars degradation reaction that agreed well with the generalized Saeman kinetic model. Both the rates of reducing sugars production and degradation varied with temperature and catalyst loading. Higher temperature and catalyst loading promoted the rates of sugars production reaction more than the rate of degradation reaction. This is evident from the relatively larger rate constant of sugars production (k1) than the rate constant of degradation (k2). The activation energy for sugars production and degradation was 125.1kJmol−1 and 60.8kJmol−1 respectively. These values are lower than the literature reported values for sulfuric acid-catalyzed saccharification confirming its employment suitability for reducing sugars production. The good recovery of [BMIM]Cl and good reusability of A15 further substantiated the feasibility of the process. The recovery of ionic liquid was improved by employing a multiple step aqueous biphasic system in this study. Approximately 60% of the ionic liquid was recovered by 3-step aqueous biphasic system. This finding is on par with the reported literatures using aqueous biphasic system to recover ionic liquid. Equally robust, the solid acid catalyst regained its saccharification performance after regeneration for a total of three cycles.

Preparation of high crystallinity cellulose nanocrystals (CNCs) by ionic liquid solvolysis

High crystallinity cellulose nanocrystals (CNCs) were successfully prepared from microcrystalline cellulose (MCC) by utilization of 1-butyl-3-methylimidazolium hydrogen sulfate (BmimHSO4) as both catalyst and solvent. Interestingly, it was found that crystallinity of CNCs was improved with increase in temperature which attributed to selective removal of the amorphous phase of cellulose performed at a higher rate with higher temperature. The successful conversion of MCC to CNCs was supported by HRTEM in which the uniform rod-like shape of CNCs was obtained. CNCs with diameter range from 15 to 20 nm and length range from 70 to 80 nm were successfully produced at 90 °C with BmimHSO4. In the present work, CNCs synthesized at different temperatures from 70 °C to 100 °C were investigated. The application of BmimHSO4 as both catalyst and solvent introduced a green chemistry approach as it does not produce any hazardous waste products and is an economical process because the recovery of ionic liquid is high (>90%).

Systematic screening methodology and energy efficient design of ionic liquid-based separation processes

A systematic methodology for the screening of ionic liquids (ILs) as entrainers and for the design of ILs-based separation processes in various homogeneous binary azeotropic mixtures has been developed. The methodology focuses on the homogeneous binary aqueous azeotropic systems (for example, water + alcohols). Additionally, a Hildebrand solubility parameter group contribution model for ILs, and ILs miscibility database have been developed to screen the miscibility of the ILs with the target solute component and these parameters are considered as the main criteria for the screening of ILs. ILs were further screened based on a combination of criteria such as stability, toxicity, and their environmental impacts. All best ILs were used as entrainers, and an extractive distillation column (EDC) and ionic liquid recovery column were designed and simulated with a process simulator to determine the overall energy consumption of the ILs-based separation processes. Among all candidates, the best IL was selected based on the minimum energy requirement obtained from the simulation. Finally, the modification of the separation process to obtain design flexibility for other azeotropic series with respect to the change in size of the target solute was investigated using the same separation process and IL entrainer to obtain the same product purity. The proposed methodology has been evaluated through a case study of binary alcoholic aqueous azeotropic separation: water + ethanol and water + isopropanol.

Recycling and recovery of ammonium-based ionic liquids after extraction of metal cations from aqueous solutions

Abstract The recycling and recovery of ionic liquids (ILs) after the extraction of metal ions were investigated by using trioctylmethyl ammonium camphorate and trioctylmethyl ammonium dodecanedioate, which were synthesized from trioctylamine. The metal ions used in the aqueous solutions were: cadmium, copper and lead with initial concentrations of 50 and 100 ppm. In all the cases, the extraction percentage results were above 90%. After the extraction, the IL recovery was carried out by using solvents with medium polarity indexes. The present work features an extraction mechanism that goes through the use, recycling, recovery and reuse of ILs applied in the metal extraction process.

Energy-efficient extraction of fuel from Chlorella vulgaris by ionic liquid combined with CO2 capture

Algae-sourced feedstocks remain confined to commercialization because of the high cost and energy consumption of biomass cultivation and feedstock extraction. In this study, to reduce the energy consumption required for algae extraction, experiments with Chlorella vulgais extraction by ionic liquids (ILs) combined with CO2 capture were conducted considering that captured CO2 by ILs can compensate the energy consumption of extraction. The results showed that the addition of CO2 to [BMIM][BF4] increased the lipid yield of Chlorella vulgaris from 68.0% to 75.6%. The properties of synthesized biodiesel from C. vulgaris lipids met the UNE-EN 14214 European biodiesel standard except for oxidative stability. Protein denaturation and degradation were found during the lysis of algae cells. Approximately 82.2wt.% of the total extracted proteins could be precipitated during both algae lysis and supernatant liquid drying. A microalgae-to-biofuel route including C. vulgaris extraction and CO2 capture was proposed that involves wet algae input and delivery outputs of water, biodiesel, pyrolysis oil, proteins, sugars, biogas and glycerol. Fossil energy ratios (FER) based on the overall energy balance were 3.30 (n=1, n is the volume ratio of IL to wet algae) and 3.84 (n=2) for [BMIM][BF4] with CO2 capture, approximately 2.5 times those based on commercially available technologies. The possibilities of synthesizing novel ILs that show both high CO2 absorption and good abilities in cell wall breakage are discussed. More progress is greatly needed to reduce IL recovery loss.

Simultaneous saccharification and fermentation of cellulose in ionic liquid for efficient production of α-ketoglutaric acid by Yarrowia lipolytica.

Ionic liquids (ILs) are benign solvents that are highly effective for biomass pretreatment. However, their applications for scale-up biorefinery are limited due to multiple expensive IL recovery and separation steps that are required. To overcome this limitation, it is very critical to develop a compatible enzymatic and microbial biocatalyst system to carry the simultaneous saccharification and fermentation in IL environments (SSF-IL). While enzymatic biocatalysts have been demonstrated to be compatible with various IL environments, it is challenging to develop microbial biocatalysts that can thrive and perform efficient biotransformation under the same conditions (pH and temperature). In this study, we harnessed the robust metabolism of Yarrowia lipolytica as a microbial platform highly compatible with the IL environments such as 1-ethyl-3-methylimidazolium acetate ([EMIM][OAc]). We optimized the enzymatic and microbial biocatalyst system using commercial cellulases and demonstrated the capability of Y. lipolytica to convert cellulose into high-value organics such as α-ketoglutaric acid (KGA) in the SSF-IL process at relatively low temperature 28 °C and high pH 6.3. We showed that SSF-IL not only enhanced the enzymatic saccharification but also produced KGA up to 92% of the maximum theoretical yield.

Separation of Lignin from Corn Stover Hydrolysate with Quantitative Recovery of Ionic Liquid.

Abundant lignocellulosic biomass could become a source of sugars and lignin, potential feedstocks for the now emergent bio-renewable economy. The production and conversion of sugars from biomass have been well-studied, but far less is known about the production of lignin that is amenable to valorization. Here we report the isolation of lignin generated from the hydrolysis of biomass dissolved in the ionic liquid 1-butyl-3-methylimidazolium chloride. We show that lignin can be isolated from the hydrolysate slurry by simple filtration or centrifugation, and that the ionic liquid can be recovered quantitatively by a straightforward wash with water. The isolated lignin is not only free from ionic liquid, but also lacks cellulosic residues and is substantially depolymerized, making it a promising feedstock for valorization by conversion into fuels and chemicals.

Saccharification of Lignocellulosic Biomass under Mild Condition Using Ionic Liquid

Biomass is expected to be an alternative resource to fossil resources. In this study, the development of a biomass conversion method into the valuable chemical, reducing sugar, was examined. For the conversion, thermochemical technology was focused on for its advantage of short reaction time, and ionic liquid was focused on as a reagent to overcome the unpreferable disadvantage of thermochemical technology, which is the low selectivity. Cedar and crystalline cellulose were pretreated with ionic liquid for reforming into desirable precursors of reducing sugar. Especially when they were pretreated by 1-ethyl-3-methylimidazolium methylphosphonate at 150°C for 1 h, the pretreatment worked effectively by decreasing the crystallinity of samples. Pretreated cedar and crystalline cellulose were converted into reducing sugar under hydrothermal conditions, respectively, by 39 C-% and 90 C-%. Recovery of ionic liquid was also examined. When cedar was used as a material, lignin was dissolved into ionic liquid through pretreatment, which was undesirable because of difficult separation thereof. When crystalline cellulose was used as a material, 98.3% of the ionic liquid was recovered after the conversion with the highest yield of reducing sugar (90 C-%).

Aqueous two‐phase/reverse micelle continuous process for recycling and simultaneous purification of polar ionic liquid from enzymatic hydrolysate

AbstractBACKGROUNDRecently, ionic liquid (IL) involved pretreatment and enzymatic saccharification of cellulose toward biofuel have attracted extensive attention. However, separation and recycling of ionic liquid from enzymatic hydrolysate pose challenges to their large‐scale application. Almost all present work has focused on the recovery rate of IL, but little work has been done to analyze the purity and functioning of recovered IL. In this work, IL was recycled and purified from hydrolysis mixtures using an aqueous two‐phase/reverse micelle process (APTs/RM).RESULTSAn ionic liquid recovery yield of 92.3% and purity of 99.1% was obtained from the aqueous two‐phase and reverse micelles extraction process with optimized parameters. Impurities (e.g. lignin, HCO3−, (NH4)2SO4 and enzyme protein) were removed from the ionic liquid. When recycling over 10 runs, the APTs/RM process has distinct advantage over other reported recovery methods.CONCLUSIONIt is demonstrated that the APTs/RM process is efficient for recycling and simultaneous purification of polar ionic liquid from an enzymatic hydrolysate mxiture. This method is potentially sustainable, efficient, and attractive for large‐scale application. © 2014 Society of Chemical Industry

Ionic liquid recovery alternatives in ionic liquid‐based three‐phase partitioning (ILTPP)

Ionic liquid‐based three‐phase partitioning (ILTPP) is a promising technique to recover high‐added value proteins at the liquid–liquid interface. Its economic and environmental performance highly depends on the net ionic liquid consumption. Alternatives to maximize the fraction of ionic liquid that can be recycled are studied. It is demonstrated that the addition of extra salt, previously proposed in literature, has a very limited effect on ionic liquid recovery for relatively high protein concentrations in the feed stream, and that it may even lead to an increase of the ionic liquid losses under certain conditions. However, small additions of salt are shown to be effective and profitable from an economic point of view. Vacuum evaporation is shown to allow for the complete ionic liquid and salt recovery, reinforcing the sustainability and viability of ILTPP processes. © 2014 American Institute of Chemical Engineers AIChE J, 60: 3577–3586, 2014

Separation of carbohydrates and sugar alcohols from ionic liquids using antisolvents

Interest in the application of ionic liquids (ILs) for biorefining purposes has been growing in the last decade. In such biorefineries separation processes involving carbohydrates and ILs are required for process design. In this work, separation between carbohydrates or sugar alcohols and ILs by means of precipitation was studied extensively for 16 different mixtures. Process variables such as temperature, antisolvent/IL ratio, and different antisolvents, ILs and solutes were studied. Carbohydrate extraction and IL recovery in the process were evaluated. For more than 80% of the studied mixtures, ionic liquid recovery and carbohydrate extraction were higher than 83%, using the optimised conditions. These results show the suitability of antisolvents for separation technologies in biorefining processes using ILs.

利用双水相分离回收离子液体的研究进展

The investigation on the separation and recovery of ionic liquids from water would be of great importance in reducing environmental impact of ionic liquids, enhancing their utilization efficiency, decreasing their industrial cost and promoting their industrial application. In this review, we focused our attention on the research progress in the recovery of ionic liquids by using salt + ionic liquid aqueous two-phase systems, sugar + ionic liquid aqueous two-phase systems, polymer + ionic liquid aqueous two-phase systems, and carbon dioxide induced aqueous two-phase systems. The main influence factors on the recovery of the ionic liquids were analyzed, and advantages and disadvantages of different ionic liquid aqueous two-phase systems were evaluated. The development in the ionic liquid recovery was prospected and the challenges were stressed.

Ionic Liquid-Based Aqueous Biphasic Systems with Controlled Hydrophobicity: The Polar Solvent Effect

Recovery of ionic liquids (IL) is necessary and urgent because of increasing production costs and potential environmental pollution. Dipolar aprotic solvents (dimethyl sulfoxide, DMSO; N,N-dimethylformamide, DMF; and N,N-dimethylacetamide, DMCA) and polar protic solvents (methanol, ethanol, and n-butanol) were used as cosolvents and antisolvents, respectively. These compounds have crucial effects on the separation and purification of ILs. We determined the effect of different polar solvents on the formation of aqueous biphasic systems (ABSs) using K3PO4 to control the hydrophobicity of 1-alkyl-3-methylimidazolium chloride ([Cnmim]Cl). Phase equilibria of the ABSs comprising IL + K3PO4 + water in the presence of the polar solvents were obtained at 298 K and at atmospheric pressure. In general, the IL aptitude that induced the formation of ABS in the presence of the polar solvents increased with decreasing hydrogen bond basicity and polarizability of the polar solvents in the following order: none < methano...

Determination and Correlation of Solubilities of Four Novel Benzothiazolium Ionic Liquids with PF−6 in Six Alcohols

Four novel benzothiazolium ionic liquids with PF−6([C1Bth][PF6], [C4Bth][PF6], [C5Bth][PF6] and [C6Bth][PF6]) were synthesized, and the rang of their melting points were determined between 358.35 K–424.05 K. The relationship of their melting points and the length of the straight alkyl chain on cation reflected ‘S’ type tendency. Then, the solubilities of the four ionic liquids in six lower alcohols (methanol, ethanol, 1-propanol, 2-propanol, 1-butanol and 2-methyl-1-propanol) were measured in the temperature rang of 253.15–383.15 K at atmospheric pressure with static analytical method, respectively. It was found that [C6Bth][PF6] in all investigated ionic liquids had the largest solubility in six alcohols and the solubility of [C4Bth][PF6] in methanol was very sensitive for temperature in 313.15–333.15 K, which was so-called “temperature-sensitivity”. This feature is of great significance to their application of catalyzing reaction or extraction process, and makes the recovery and reuse of ionic liquids (ILs) become easier. Moreover, the experimental solubility data were correlated with the modified Apelblat equation and λh equation, respectively. It was found that the result of correlation using two divided temperature ranges was better than that of using the whole temperature range.

Ionic liquid-based three phase partitioning (ILTPP) systems: Ionic liquid recovery and recycling

Ionic liquid-based three phase partitioning (ILTPP) is a promising technique to recover lactoferrin, a high-added value whey protein, because it combines the advantages associated with the use of ionic liquids and the feasibility of the product recovery characteristic of three phase partitioning. The recyclability of the ionic liquid is essential for the feasibility and development of ILTPP technique, due to the high cost and environmental impact associated with the discharge of this type of compounds. For this purpose, the thermodynamic characterization of the systems of interest for ILTPP, which are based on the use of 1-butyl-3-methylimidazolium trifluoromethanesulfonate (BmimTfO) and sodium dihydrogenophosphate (NaH2PO4), is here performed to determine the composition of the liquid phases in equilibrium and the distribution coefficient between them. In addition, the fraction of ionic liquid that cannot be reused in the ILTPP process has been assessed, concluding that the recyclability of this compound is highly dependent on the protein concentration in the feed stream. At high protein concentrations (2gL−1) and moderate ILTPP efficiencies (around 80%) it is possible to recycle more than 99% of the ionic liquid, which improves both the economic and environmental performance of the ILTPP process.

Extraction of dimethyl sulfoxide using ionic-liquid-based aqueous biphasic systems

To combine ionic liquid (IL) recovery with cosolvent separation in biomass processing, the quaternary aqueous biphasic systems (ABSs) formed by IL, kosmotropic salt and water in the presence of dimethyl sulfoxide (DMSO) are herein proposed. Three main parameters were evaluated through the phase diagrams and the DMSO partitioning process: the IL cation and anion structure, the salt anion, and the temperature. In all systems and conditions texted, DMSO preferentially dissolves in the IL-rich phase. The results obtained indicate that, the partitioning process is essentially controlled by the IL cation interactions with DMSO. The partition coefficients (KDMSO) displays a maximum for the system formed by [C6mim]Cl. The KDMSO value increases monotonically with the initial concentration of DMSO, and it decreases in the systems with different salts: K3PO4>K2HPO4>K2CO3>KOH. The increase of temperature reduces the partition coefficients. Moreover, densities and pH of both aqueous phases were measured at 298.15K to evaluate the properties of the systems. The results gathered indicate that the densities and pH values of the two phases can be affected by the nature of IL and its initial concentrations, and the smaller density differences between the fluids, the lower the partition coefficients of DMSO.

COMPARISON OF DIFFERENT IONIC LIQUIDS PRETREATMENT FOR CORN STOVER ENZYMATIC SACCHARIFICATION

Recently, application of ionic liquids (ILs) has received much attention due to their special solvency properties as a promising method of pretreatment for lignocellulosic biomass. Easy recovery of ionic liquids, chemical stability, temperature stability, nonflammability, low vapor pressure, and wide liquidus range are among those unique properties. These solvents are also known as green solvents due to their low vapor pressure. The present study was set to compare the effect of five different ILs, namely, 1-ethyl-3-methylimidazolium acetate ([EMIM][Ac]), 1-butyl-3-methylimidazolium chloride ([BMIM][Cl]), 1-ethyl-3-methyl imidazolium diethyl phosphate ([EMIM][DEP]), 1-allyl-3-methylimidazolium chloride ([AMIM][Cl]), and 1-ethyl-3-methylimidazolium-hydrogen sulfate ([EMIM][HSO4]), on corn stover in a bioethanol production process. The performance of ILs was evaluated based on the change observed in chemical structure, crystallinity index, cellulose digestibility, and glucose release. Overall, [EMIM][Ac]-pretreated corn stover led to significantly higher saccharification, with cellulose digestibility reaching 69% after 72 hr, whereas digestibility of untreated barley straw was measured at only 21%.

Study on the recovery of ionic liquids from dilute effluent by electrodialysis method and the fouling of cation-exchange membrane

With the wide application of ionic liquids (ILs) in various fields, developing efficient techniques to recover ILs from effluent is an urgent demand for the cost reduction and the environmental protection. In this study, an electrodialysis (ED) method was used to recover 1-butyl-3-methylimidazolium chloride ([Bmim]Cl) IL from aqueous solution as model effluent. The influences of initial IL concentration and applied voltage on the current efficiency, removal ratio, desalination ratio, membrane flux and specific energy consumption during the ED process were investigated. It was found that the removal ratio and desalination ratio increases with the increasing of initial IL concentration and applied voltage. The current efficiency decreases with the increasing of initial IL concentration and the current efficiency reached the maximum value of 94.3% at 25 V. Besides, as the applied voltage increases, the membrane flux increases and the specific energy consumption decreases. Moreover, the fouling of cation-exchange membrane was also discovered after the desalination of IL. The deposits on the surface or into the membrane which is probably caused by [Bmim]+ was characterized by scanning electron microscopy, elemental analysis and Fourier transform infrared.

Recovery of an ionic liquid [BMIM]Cl from a hydrolysate of lignocellulosic biomass using electrodialysis

In this study, an ionic liquid was recovered in electrodialysis (ED) of the liquid fraction (hydrolysate) from the softwood biomass pretreated with an ionic liquid, [BMIM]Cl (1-butyl-3-methylimidazaolium chloride). The influence of operating parameters (electrical potential and ionic liquid concentration) on the ED performance was investigated. The results showed that the process performance increased with increasing electrical potential and ionic liquid concentration. In this study, the process performance decreased due to the deposition of ionic liquid during ED experiments of the hydrolysate. However, the process performance was recovered by chemical cleaning as reversible fouling. A feasibility study on the ionic liquid recovery showed that the ED process had better performance than other processes without significant fouling effect as a feasible method to recover ionic liquids from hydrolysate.