Bifunctional Ionic Liquid Research Articles

Dicationic ionic liquids as effective catalysts in solvent free strecker synthesis

A benign protocol for the Strecker synthesis of α-aminonitriles in the bifunctional ionic liquids has been reported here. The imidazolium based dicationic ionic liquids with Cl−, NO2− and PF6− anions efficiently catalysed the conversion of a variety of aldehydic substrates into corresponding α-aminonitriles upon treatment with aniline and trimethylsilylcyanide. B[MIm]2[PF6]2 provided 97% of the product in a short interval of 30 ​min with 5 ​wt% of it. Ionic liquids were recovered efficiently and re-used in the reaction for consecutive 5 cycles without much significant loss in its activity. Thus, the current protocol possesses the advantageous features of being less-hazardous, benign, solvent free and reproducible.

Techno-economic assessment of the separation of samarium, europium and gadolinium

Spiking of the rare earth demand and price globally has put tremendous pressure to look for a new alternative in extractant that could provide better separation and higher output, yet with minimal cost. This work aimed to perform the techno-economic assessment on the new extractant against the conventional extractants; DEHPA and 2-ethylhexyl phosphoric acid-2-ethylhexyl ester (EHEHPA) in pursuance of evaluating the feasibility of these extractants on an industrial scale. This work focused on a recent extractant type, which incorporates two common extractants and produces a bifunctional ionic liquid called [A336][DEHPA]. It is a mixture of Aliquat 336 (A336) and di-(2-ethylhexyl)phosphoric acid (DEHPA) through acid/base neutralization. Previously, [A336][DEHPA] has shown good extraction capabilities with low extraction stages in the separation of samarium, europium, and gadolinium. EHEHPA has been selected as the baseline using the information from the literature. The assessment is divided into two scenarios; 1) the separation of samarium from the middle rare earth concentrate and 2) the separation of europium and gadolinium. The analysis outcome reveals that for both scenarios, DEHPA manages to provide 99.9% purity and 90% recovery of rare earth with lower investment compared to the EHEHPA. Although the [A336][DEHPA] could provide an environmental-friendly option, the enormous expenses make the process infeasible.

Solvent extraction of lithium from simulated shale gas produced water with a bifunctional ionic liquid

The recovery of lithium from brines is a major field of study with an increase in lithium-ion batteries consumption and the subsequent growth of lithium consumption. The recovery of lithium from shale gas produced water is promising since these sources could contain non-negligible concentrations of lithium. In this study, lithium extraction was investigated using solvent extraction with a bifunctional ionic liquid (IL) as an extracting agent diluted in n-dodecane. The components of these IL are cheap and commercially available products, namely Aliquat-336 (methyltrioctylammonium chloride) and DEHPA (di-(2-ethylhexyl)phosphoric acid), and its synthesis is straightforward. Lithium extraction was optimized by studying several experimental parameters (mixing time, aqueous phase acidity, IL concentration in the solvent phase, aqueous lithium concentration). The mechanism of extraction was detailed, and the stripping was shown to be complete with 0.5 mol.L−1 of HCl. A two stages strategy was defined to recover lithium from synthetic brine. In the first stage, divalent metals are removed using five successive cycles of extraction with DEHPA (1 mol.L−1) dissolved in n-dodecane. In the second stage, the IL extracting agent [Aliquat-336][DEHPA] (1 mol.L−1) allowed to remove 83% of lithium in one cycle of extraction, which is higher than reported solvent extraction results with conventional extracting molecules.

Separation of Mo(VI), V(V), Ni(II), Al(III) from synthetic hydrochloric acidic leaching solution of spent catalysts by solvent extraction with ionic liquid

The recovery of metals from spent petroleum catalysts has been attracting much attention owing to an increase in the metal demand. In this work, bi-functional ionic liquid, ALi-D2, in kerosene synthesized by Aliquat336 and D2EHPA was employed for the separation of Mo(VI), V(V), Ni(II) and Al(III) from the synthetic HCl leaching solution of spent petroleum catalyst. The metal ions were efficiently separated by adjusting the concentration of ALi-D2 and acidity of the leaching solution. First, Mo(VI) was selectively extracted into ALi-D2 together with a small amount of V(V). The co-extracted V(V) was removed from the loaded ALi-D2 by selective stripping with H2SO4 solution. Then the Mo(VI) was stripped from the stripped ALi-D2 with NH4OH solution. Second, the V(V) in the raffinate was selectively extracted by ALi-D2 over Al(III) and Ni(II). Al(III) was selectively extracted over Ni(II) from the raffinate by extraction with ALi-D2 after adjusting the pH at 2. The solvent extraction reaction of metal ions by ALi-D2 was identified by applying slope analysis method. The interaction between extractant and metal complexes was analyzed by FT-IR spectra. A process was proposed to separate the four metal ions in the leaching solution based on the results.

Separation of samarium from medium rare earth mixture using multi-stage counter-current extraction

A large number of bifunctional ionic liquid extractant with ammonium-based have been formulated to separate and extract rare earth (RE) ions with better extraction efficiencies and selectivities compared to conventional extractant. In this paper, a methodical study for the separation of samarium from a mixture of samarium, europium, and gadolinium using bifunctional ionic liquid, [A336][P204] was developed. The optimum condition for the extraction was explored in regard to the concentration and type of acid as well as the organic to the aqueous ratio of the mixture. The sum of extraction and scrubbing stages are then calculated using the counter-current theory. The target purity and recovery ratio was set to 99.9% and 90%, respectively. Multi-stage of counter-current extraction process for three, four, and five stages were developed to simulate the extraction process. As a result, extraction with 3.0 M HNO3 and 4:1 organic to aqueous ratio selected as the best condition based on the value of separation factor, β: 2.81. The number of stages calculated by the theory matches the stages done experimentally, which is four. The outcome of the extraction indicates a high recovery value (>90%) but with a poor purity ratio (<70%). For scrubbing stages, by theory 13 stages is required, however in the experimental work, 18 stages needed to achieve the purity of >99%. The counter-current simulation of the samarium extraction from the mixed RE solution showed that a complete separation with excellent purity and recovery is possible and a process flow sheet has been presented.

Permeation of Phenylalanine through Polymer Inclusion Membrane Containing Bi-functional Ionic Liquid

Permeation of Phenylalanine through Polymer Inclusion Membrane Containing Bi-functional Ionic Liquid

Experimental and Theoretical Study on Sm/Eu-Gd Extraction by P204 and [A336][P204

Extraction of rare earth using ionic liquid as extractant become an alternative practice to replace the common volatile organic solvents in recent years. In general, the work to extract rare earth element, require a large number of extraction stage, and different extractant used resulted in different number of extraction needed. Therefore an analysis on the theoretical number of stages is necessary prior to laboratory work. This study was designed to compare between the number of extraction stages required by 2-ethylhexyl phosphoric acid mono 2-the ester (P204), a common rare earth extractant with a bifunctional ionic liquid, and [A336][P204] in a counter-current extraction process for the separation of Sm in Sm-Eu-Gd mixed solution. The value of the separation factor (β) of both extractants, was obtained from the experimental work, while other process parameters were calculated using the counter-current theory developed by Xu Guangxian. Extraction of Sm using [A336] [P204] was optimum in 3.0 M of nitric acid, with organic to aqueous (O/A) ratio of 4:1, while the optimum condition for P204 was when the medium was 2.0 M of hydrochloric acid and 7:3 of O/A ratio. The β value for the optimized condition for P204 was lower compared to the condition for [A336][P204] at β:1.93 and β:2.81, respectively. To derive an optimum extraction condition to calculate the number of extraction stage, target purity and recovery ratio were set to 99.9% and 90%, respectively, for both extractants. As a result, [A336][P204] was able to reduce the number of extraction stage by 5 compared to P204. The result indicated that [A336][P204] is preferable over P204 from the viewpoint of economic efficiency.

Synthesis of succinimide based ionic liquids and comparison of extraction behavior of Co(II) and Ni(II) with bi-functional ionic liquids synthesized by Aliquat336 and organophosphorus acids

Two new succinimide compounds such as 3-butyl-1-methyl-1H-imidazol-3-ium 4-(dioctylamino)-4-oxobutanoate ([N88SA]−[C4min]+) and 1-butylpyridin-1-ium 4-(dioctylamino)-4-oxobutanoate ([N88SA]−[C4Py]+) were synthesized as task-specific ionic liquids (TSILs) for the extraction of metal ions. The extraction behavior of Co(II) and Ni(II) from chloride solution was compared between these TSILs and Bif-ILs synthesized from Aliquat336 and organophosphorus acids such as Cyanex 272, PC 88A and D2EHPA. The extraction percentage of Co(II) and Ni(II) by TSILs was eight times higher than that by Bif-ILs at the initial pH of 4.0. Moreover, the extraction percentage of Ni(II) by the TSILs was slightly higher than that of Co(II). However, Bif-ILs extracted more hydrogen ions than TSILs. The extraction of Co(II) and Ni(II) by [N88SA]−[C4min]+ was higher than that by [N88SA]−[C4Py]+. The addition of TBP to TSILs reduced the extraction of metals but the loss of TSILs into the aqueous was significantly decreased. Succinimide ionic liquids can be employed for the extraction of metals from weak acidic solutions.

Comparison of the Extraction and Stripping Behavior of Iron (III) from Weak Acidic Solution Between Ionic Liquids and Commercial Extractants

Fe(III) can be easily extracted from weak acidic solutions by organophosphorus extractants, but stripping a large amount of Fe(III) from the loaded extractants is very difficult. The extraction and stripping of Fe(III) from 2 pH chloride and sulfate solutions was performed with ionic liquids(ILs) and organophosphorus acidic extractants, and the behaviors compared. As ionic liquids, two succinimides ([N88SA][C4min] and ([N88SA][C4Py]) were used, and bi-functional ionic liquids (Bif-ILs) synthesized from Aliquat336 and the organophosphorus acids Cyanex272, D2EHPA, and PC88A were employed. The extraction of Fe(III) by the ILs and extractants employed in this work was in the following order: organophosphorus extractants > Bif-ILs > succinimide ILs. The extraction of Fe(III) by succinimide ILs and Bif-ILs was higher from the chloride solution than from the sulfate one, while the nature of the medium had little effect on the extraction of Fe(III) by the organophosphorus extractants. FT-IR spectra confirmed the ion exchange mechanism of Fe(III) by the succinimide ILs. There was little difference in the stripping of Fe(III) by H2SO4 from the loaded Bif-ILs and the organophosphorus acids. However, stripping of Fe(III) from the loaded Bif-ILs using HCl did not readily occur. Fe(III) was readily stripped from the loaded [N88SA][C4min] and [N88SA][C4Py], and the HCl solution was more effective for stripping than H2SO4. [N88SA][C4min] is considered a promising new extractant for the recovery of Fe(III) based on its Fe(III) extraction and stripping behavior from weak acidic solution. Key words: ionic liquids, succinimide, extraction, stripping, iron(III)

Synergistic catalysis of acid–base bifunctional ionic liquids for pentanal self‐condensation reaction

AbstractBACKGROUNDPentanal self‐condensation to 2‐propyl‐2‐heptenal is an important process of carbon chain extension for industrial manufacture of 2‐propylheptanol. This reaction in industry employs an aqueous caustic alkali catalyst, causing several problems of equipment corrosion, treatment of alkali wastewater, etc. Herein, several acid–base bifunctional ionic liquids were synthesized for catalyzing pentanal self‐condensation.RESULTS[PEmim]Cl‐0.5Zn(CH3COO)2 exhibited a better catalytic performance, and the yield and selectively of 2‐propyl‐2‐heptenal could reach 82.0% and 86.6%, respectively. The recovered [PEmim]Cl‐0.5Zn(CH3COO)2 could be reused three times after being regenerated without a significant loss in its catalytic performance. The structures and charge properties of [PEmim]Cl‐Zn(CH3COO)2 and a complex of [PEmim]Cl‐Zn(CH3COO)2 and pentanal were simulated by density functional theory calculation. The results show that the action of acid and base sites of [PEmim]Cl‐Zn(CH3COO)2 can effectively activate pentanal by enhancing the electrophilicity or nucleophilicity of different pentanal molecules.CONCLUSIONThe acid–base synergetic effect of [PEmim]Cl‐Zn(CH3COO)2 could account for its high catalytic performance. An acid–base synergetic catalysis mechanism of [PEmim]Cl‐Zn(CH3COO)2 in pentanal self‐condensation was established. © 2019 Society of Chemical Industry

Bifunctional ionic liquid and conducting ceramic co-assisted solid polymer electrolyte membrane for quasi-solid-state lithium metal batteries

Development of solid polymer electrolytes (SPEs) with high thermal and mechanical stability and fast ion conductivity is the key for high-performance lithium metal batteries (LMBs) with high safety. In this work, a flexible poly-(ethylene oxide) (PEO)-lithium bis(trifluoromethanesulfonyl)imide) (LiTFSI) SPE assisted with a bifunctional ionic liquid (IL) of tetrabutylphosphonium 2-hydroxypyridine (TBPHP) as well as a garnet-type fast-ion conducting ceramic of Li6.4La3Zr1.4Ta0.6O12 (LLZTO) was fabricated via a solvent-free procedure and applied for the LMBs. It is found that the tetrabutylphosphonium cation (TBP+) and 2-hydroxypyridine anion (HP−) of IL effectively tuned the crystallinity of PEO and enhanced lithium ion (Li+) transference, respectively, and the TBPHP and LLZTO played a synergistic role in improving the performance of SPEs. Meanwhile, the density functional theory (DFT) study was performed to understand the interaction between TBPHP and LiTFSI. As a result, the obtained PEO8-LiTFSI-TBPHP-12.5% LLZTO composite SPE possessed a high ionic conductivity of 9.39 × 10−4 S cm−1 at 50 °C and a wide electrochemical stability window (more than 5 V) with significantly promoted uniform Li plating/stripping properties. The quasi-solid-state-LMBs assembled with LiFePO4 cathode also rendered excellent cycling stability with a high discharge capacity above 150 mA h·g−1 even after 100 cycles at 0.2 C and 50 °C. Besides, the fabricated flexible pouch cell showed excellent performance. It is expected that such a bifunctional ionic liquid and conducting ceramic co-assisted polymer composite could be a promising solid electrolyte for the next-generation of safe LMBs.

Development of a reactive extraction process for isobutyl isobutyrate formation intensified by bifunctional ionic liquid

Isobutyl isobutyrate (IBIBE) is a typical long-chain ester widely used as a solvent, additive, or raw material. To address problems such as acidic waste emission and tedious downstream separation in traditional synthesis routes, a reactive extraction process concept employing the ionic liquid (IL) 1-butyl-3-methylimidazolium hydrogen sulfate ([BMIm][HSO4]) as a dual catalyst and solvent is proposed. To develop such an intensified process, thermodynamic analysis of the reaction system is firstly performed. Liquid-liquid equilibria indicate that [BMIm][HSO4] is a proper extractant that can not only remove the formed IBIBE from the esterification system via phase splitting but also keep the reactants in the IL phase, both facilitating the forward reaction and thus improving the conversion of the reactant and the purity of IBIBE. The kinetics of the esterification is then experimentally determined and fitted using the activity-based kinetic model, which suggests the good catalytic performance of [BMIm][HSO4]. Combining the NRTL model and activity-based kinetic model, a reactive extraction process for IBIBE formation is developed and simulated. High purity of IBIBE (0.9799) and high conversion (0.9931) are obtained.

Separation and recovery of Sc(III) from Mg–Sc alloy scrap solution through hollow fiber supported liquid membrane (HFLM) process supported by Bi-functional ionic liquid as carrier

ABSTRACTThe Mg–Sc alloy leach solution bearing 2.5 g/L Sc(III), 25.0 g/L Mg(II) and 0.5 M HCl was subjected to investigate for separation of Sc(III) by hollow fibre liquid membrane (HFLM) followed by its recovery through oxalate precipitation route. Ionic liquid (IL) R4ND derived from commercial organo-phosphoric acid (D2EHPA) and aliquot-336 was used as carrier in this study. Equilibrium study ensures on extraction of Sc(III) as ScCl3 with association of 3 mole of R4ND in the extracted phase. The role of chloride and R4ND concentration appears to be critical while enhancing the Sc flux (JSc). The complex formation during extraction of Sc(III) into the carrier phase was confirmed from FTIR analysis. Maximum JSc of 10.41 × 10−5 mol/m2.s was obtained at the optimum condition: pH 4.0, 0.4 M R4ND, flow rate 150 mL/min., 6.0 M NaOH, Feed: Strip = 3:1 and after 90 min. of HFLM continuous run of almost all scandium separation from scrap solution was achieved on yielding threefold enrichment into the strip phase which bears ~7.49 g/L of scandium. The stripped solution resulted was precipitated using oxalic acid and substantially calcined to produce Sc2O3. The pure form of Sc2O3 produced in the present work was ensured from XRD analysis.

Recent advances in metal extraction improvement: Mixture systems consisting of ionic liquid and molecular extractant

Abstract Ionic liquids (ILs), also termed “green” and “designer” solvents, have been proposed as promising solvents for diverse applications. This review focused on the improvements brought about by mixing ILs with molecular extractants (MEs) in solvent extraction processes for metal extraction and separation. Mixture systems consisting of IL with ME were collected and discussed on the basis of the functional cations of ILs, such as ammonium-type, phosphonium-type and imidazolium-type ILs. IL was found to play a role as an active component by generating a new acid/base coupling bi-functional ionic liquid (ABC-BIL) or as a diluent when combined with acidic or neutral ME in IL-ME mixture systems. The merits and drawbacks of IL-ME systems were reviewed and compared with conventional ME systems alone in terms of the preparation route, separation behavior and extraction mechanism. Further approaches to the improvement of IL-ME systems, such as extraction enhancement, stripping and regeneration, were discussed. The summaries and comparisons made in the present review may indicate future directions for the development and application of ILs in metal solvent extraction technology.

Upgrading of HMF and Biomass‐Derived Acids into HMF Esters Using Bifunctional Ionic Liquid Catalysts under Solvent Free Conditions

AbstractCatalytic conversions of biomass‐derived compounds like 5‐hydroxymethylfurfural (HMF) and levulinic acid (LA) to value‐added compounds have drawn tremendous interest in recent years. In this study, we report the catalytic upgrading of HMF into HMF levulinate and HMF esters under solvent‐free condition using laboratory‐synthesized bifunctional ionic liquid (IL) catalysts. The synthesized ILs were characterized using 1H NMR and 13C NMR spectroscopy. Pyridine Fourier transform Infrared spectroscopy (FT‐IR) studies were carried out for their detailed Brønsted and Lewis acidity characterization. Catalytic activity of these ILs was tested in the conversion of HMF into HMF levulinate in the temperature range of 75 to 120 °C and 5 h reaction time using 150 mg each of IL catalyst and 4 Å molecular sieves with LA to HMF molar ratio of 5:1. It was found that strong dual acidic catalyst [SMIM][FeCl4] was found to exhibit highest catalytic activity with 97.0% HMF conversion and 78.1% yield of HMF levuliante. Catalytic activity decreased in the order: [SMIM][FeCl4]&gt; [BSO3HMIm][FeCl4]&gt; [SMIM][Cl]&gt; [BSO3HMIm][Cl]&gt; [BMIM][FeCl4]&gt; [BMIM][Cl]. The reaction parameters such as reaction time, temperature, mole ratio of the reactants, and effect of catalyst loading were optimized.The recyclability of these bifunctional catalysts was also tested and found to be intact for three recycles.

Studies on Liquid-Liquid Extraction of Yttrium and Separation from Other Rare Earth Elements Using Bifunctional Ionic Liquids

ABSTRACTSolvent extraction of yttrium(III) from chloride and nitrate solutions were carried out using two bifunctional ionic liquids Cyphos IL 104 and [A336/Cy272]. Comparative study with their constituent extractants showed higher extraction abilities of the ionic liquids for Y(III). The extraction behavior of yttrium using the above ionic liquids was studied as function of different parameters. Ion association neutral complexes were formed in the organic phase. 0.5 M HNO3 could strip 82% and 75.6 % yttrium from the loaded organic phases of 0.01M [A336/Cy272] and Cyphos IL 104, respectively. Separation studies involving binary systems were also investigated.

Surface engineering of a chromium metal-organic framework with bifunctional ionic liquids for selective CO2 adsorption: Synergistic effect between multiple active sites

Targeting CO2 capture application, a new strategy for building multiple adsorption sites in metal-organic framework MIL-101(Cr) was constructed through the incorporation of diethylenetriamine-based ionic liquid (DETA-Ac) via a post-synthetic modification approach. The DETA-Ac, with multi-amine-tethered cation and acetate anion, could not only provide additional binding sites, but also enhance the affinity of framework surfaces toward CO2. Simultaneously, the high surface area and large cage size of MIL-101(Cr) ensured the better dispersion of IL, thus exposing more active sites for CO2 adsorption. In addition, enough free space was still retained after functionalization, which facilitated CO2 transport and allowed the Cr(III) sites deep within the pores to be accessed. The multiple adsorption sites originating from IL and MOF were found to synergistically affect the CO2 capture performance of the composite. The adsorption capacity and selectivity of DETA-Ac@MIL-101(Cr) for CO2 were significantly improved. The higher isosteric heats of adsorption (Qst) evidenced the stronger interaction between the composite and CO2 molecules. Moreover, a possible two-step mechanism was proposed to reveal the manner in which CO2 bound to the IL-incorporated frameworks. Despite the relatively high initial Qst value, the DETA-Ac@MIL-101(Cr) could be easily regenerated with almost no drop in CO2 uptake during six cycles.

Solubilization and Upgrading of High Polyethylene Terephthalate Loadings in a Low-Costing Bifunctional Ionic Liquid.

The solubilization and efficient upgrading of high loadings of polyethylene terephthalate (PET) are important challenges, and most solvents for PET are highly toxic. Herein, a low-cost (ca. $1.2 kg-1 ) and biocompatible ionic liquid (IL), cholinium phosphate ([Ch]3 [PO4 ]), is demonstrated for the first time to play bifunctional roles in the solubilization and glycolytic degradation of PET. A high loading of PET (10 wt %) was readily dissolved in [Ch]3 [PO4 ] at relatively low temperatures (120 °C, 3 h) and under water-rich conditions. In-depth analysis of the solution revealed that high PET solubilization in [Ch]3 [PO4 ] could be ascribed to significant PET depolymerization. Acid precipitation yielded terephthalic acid as the dominant depolymerized monomer with a theoretical yield of approximately 95 %. Further exploration showed that in the presence of ethylene glycol (EG), the [Ch]3 [PO4 ]-catalyzed glycolysis of PET could efficiently occur with approximately 100 % conversion of PET and approximately 60.6 % yield of bis(2-hydroxyethyl)terephthalate under metal-free conditions. The IL could be reused at least three times without an apparent decrease in activity. NMR spectroscopy analysis revealed that strong hydrogen-bonding interactions between EG and the IL played an important role in the activation of EG and promotion of the glycolysis reaction. This study opens up avenues for exploring environmentally benign and efficient IL technology for solubilizing and recycling postconsumer polyester plastics.

Tailoring Molecular Weight of Bioderived Polycarbonates via Bifunctional Ionic Liquids Catalysts under Metal-Free Conditions

Synthesis of bioderived high-molecular-weight polycarbonates over metal-free catalysts is of great importance but also challenging. In this work, a series of 1-butyl-3-methylimidazolium (Bmim) ionic liquids (ILs) were prepared as catalysts for a melt polycondensation reaction of isosorbide and diphenyl carbonate. By modifying the structures of ILs’ anions, the number-average molecular weight (Mn) of poly(isosorbide carbonate) (PIC) was effectively tailored. In the presence of a trace amount (0.05 mol % based on isosorbide) of bifunctional [Bmim][CH3CHOHCOO], the synthesized PIC possessed high Mn of 61,700 g/mol and a glass transition temperature of 174 °C, both the highest so far to the best of our knowledge. Besides, it was found that the anions with stronger electronegativity and hydrogen bond formation ability were more efficient for the formation of PIC with higher Mn. To modify the flexibility of PIC, poly(aliphatic diol-co-isosorbide carbonate)s with Mn ranging from 34,000 to 75,700 g/mol were also ...

Transformation of cellulosic saccharides into alkyl glucosides catalyzed by bifunctional ionic liquids.

Three kinds of hydrophobic/acidic bifunctional ionic liquids, which contain two different anions, were synthesized and utilized as catalysts for the conversion of cellulosic saccharides into alkyl glucosides, which exhibit a high catalytic conversion for cellobiose and cellulose with a low degree of crystallinity; the catalyst can be easily recovered and reused.