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The commercialisation of the biorefinery approach involving the integration of the multi-step valorisation of low value biomass feedstock into a variety of chemicals, fuels and bioproducts is still very limited. In this context, the present work proposes an advanced methodology that comprises a cascaded approach towards wheat straw valorisation. The studied concept lies in the employment of an aqueous solution of the acidic 1-ethyl-3-methylimidazolium hydrogen sulfate ionic liquid in a selective and efficient hydrolysis of the hemicellulose fraction of wheat straw into pentoses, namely xylose and arabinose. An experimental design was utilised to search for the optimisation parameters, resulting in a maximum 80.5 wt% pentose yield in the liquor. Furthermore, the remaining solid, which contained practically all of the initial cellulose and lignin, was processed by considering two scenarios: (i) a direct enzymatic hydrolysis of the reaction solid, which yielded 75.8 mol% glucose; or (ii) a preceding extraction of lignin followed by enzymatic saccharification of the cellulose pulp, which yielded 91.3 mol% glucose. For both scenarios, lignin-rich solid fractions were obtained with distinct purities and yields. Additionally, the second scenario allowed producing a stream of value-added aromatic (phenolic) compounds. This work also overcame the challenges in IL recycling and reuse, with a simultaneous recovery of the pentoses from the reaction liquor as high as 88.6 mol%. [ABSTRACT FROM AUTHOR]

A water-stable ionic liquid, 1-butyl-3-methylimidazolium trifluoromethanesulfonate, [C4mim][CF3SO3], is herein proposed to be used in the formation of aqueous biphasic systems (ABS) with a large range of mono- and disaccharides, as well as polyols. Binodal curves, tie-lines, and densities and viscosities of the co-existing aqueous phases, were determined for each ternary system. The proposed systems are low-viscous offering enhanced features over conventional polymer-based ABS. In addition, the partitioning of model biomolecules, such as l-tryptophan, caffeine, and β-carotene, was further investigated to ascertain the applicability of such ABS. These systems are particularly interesting in the recovery of bioactive products from natural sources, while the availability of carbon-based sources to cells constitutes a major advantage in separations from fermentative media. Moreover, the use of carbohydrates in ionic-liquid-based ABS constitutes a step forward along the biorefinery concept envisaging sustainable conversions of biomass into a broad spectrum of bio-based products. [ABSTRACT FROM AUTHOR]

Ionic-liquid-based aqueous two-phase systems are great candidates for the replacement of volatile organic compounds in typical liquid–liquid extractions. This work shows clear evidence for the complete extraction of alkaloids such as caffeine and nicotine using a single-step procedure. [ABSTRACT FROM AUTHOR]

In this work, we explore the mutual solubility of a number of mixtures of commonly used ionic liquids (imidazolium, pyridinium, phosphonium and ammonium ionic liquids) with partially fluorinated n-alcohols (C7 to C10) or perfluoroheptane. The corresponding T–x diagrams at atmospheric pressure were measured through cloud-point temperature determinations. For some selected systems under near-critical isopleth conditions, pressure effects were also studied. The results are discussed in terms of (i) shifts in the immiscibility envelopes as the cation alkyl-chain length is changed, (ii) the nature of the cation or the anion, (iii) the increasing length of the fluorinated/alkylic moiety of the partially fluorinated alcohol, or (iv) comparisons with similar systems involving normal alcohols. [ABSTRACT FROM AUTHOR]

This work unveils the formation of novel aqueous biphasic systems (ABS) formed by perfluoroalkylsulfonate-based ionic liquids (ILs) and a large number of carbohydrates (monosaccharides, disaccharides and polyols) aiming at establishing more benign alternatives to the salts commonly used. The respective ternary phase diagrams were determined at 298 K. The aptitude of the carbohydrates to induce phase separation closely follows their hydration capability, while the length of the IL cation/anion fluorinated chain also plays a crucial role. Finally, these systems were investigated as liquid–liquid extraction strategies for four food dyes. Single-step extraction efficiencies for the carbohydrate-rich phase up to 94% were obtained. Remarkably and contrarily to the most investigated IL-salt ABS, most dyes preferentially migrate for the most hydrophilic and biocompatible carbohydrate-rich phase – an outstanding advantage when envisaging the products recovery and further use. On the other hand, more hydrophobic dyes preferentially partition to the IL-rich phase, disclosing therefore these novel systems as highly amenable to be tuned by the proper choice of the phase-forming components. [ABSTRACT FROM AUTHOR]

Using ionic liquids as co-solvents may improve reaction media in enzyme-based biotechnological processes. To establish new conditions, large libraries need to be screened for bio-compatibility and protein stabilisation. Using a lipase model, we herein describe a combination of methods leading to an expedited evaluation of 61 different solvent compositions. [ABSTRACT FROM AUTHOR]

The surface hydrophobization through heterogeneous chemical modification of bacterial (and vegetable) cellulose fibers with several anhydrides (acetic, butyric, hexanoic and alkenyl succinic anhydrides) and hexanoyl chloride suspended in an ionic liquid, tetradecyltrihexylphosphonium bis(trifluoromethylsulfonyl)imide, [TDTHP][NTf2], was studied. Furthermore, in the reaction with hexanoyl chloride, another ionic liquid, N-hexyl-4-(dimethylamino)pyridinium bis(trifluoromethylsulfonyl)imide, [C6N(CH3)2py][NTf2], was used instead of common organic bases as catalyst and to trap the released HCl. The analysis of the ensuing modified fibers by FTIR, XRD and SEM clearly showed that the esterification reactions occurred essentially at the fibers' outmost layers, not affecting their ultrastructure. The degree of substitution (DS) of the ensuing esterified fibers ranged from less than 0.002 to 0.41; and in all instances, the fibers' surface acquired a high hydrophobicity. This novel approach constitutes an important strategy in the preparation of modified fibers under greener conditions relaying in the use of non-volatile solvents. [ABSTRACT FROM AUTHOR]

This work aims at identifying, amongst extreme soil biotypes at locations of high salinity and high hydrocarbon load, microbial strains able to survive short or long-term exposure to the presence of selected ionic liquids. We have evaluated the impact of ionic liquids on the diversity of the soil microbiota to identify which microbial strains have higher survival rates towards ionic liquids, and consequently those which might possibly play a major role in their biotic fate. To the best of our knowledge, this is the first study of this kind. Soils, from a region in Portugal (Aveiro) were sampled and the bacterial and fungal strains able to survive after exposure to high concentrations of selected ionic liquids were isolated and further characterised. We have mainly focused on two types of cations: imidazolium – the most commonly used; and cholinium – generally perceived as benign. The surviving microbial strains were isolated and taxonomically identified, and the ionic liquid degradation was analysed during their cultivation. The continuing exposure of the microbial strains to petroleum hydrocarbons is likely to be the basis for their acquired resistance to some imidazolium salts; also, the higher capacity of fungi – compared to bacteria – to grow, even during their exposure to these liquid salts, became evident in this study. [ABSTRACT FROM AUTHOR]

A successful process to extract lipolytic enzymes based on an aqueous biphasic system (ABS), which uses both ionic liquids (ILs) and a high charge-density inorganic salt (K2CO3), is proposed in this work. The activity of a model Thermomyces lanuginosuslipase (TlL) in some of the most common hydrophilic ILs, based on the 1-alkyl-3-methylimidazolium cation, combined with chloride, alkylsulfate, alkylsulfonate and acetate, was investigated. Several operating conditions influencing lipase activity and ABS formation were investigated. Parameters such as temperature, pH, deactivation kinetics and water content were evaluated in order to propose a viable extraction process. A deeper analysis in terms of enzyme deactivation kinetics was carried out, and the data were modelled through a series-type deactivation equation. ATR-FTIR studies aimed at identifying the TlL structure in selected ILs have also provided an insight into the enzyme deactivation behaviour. [ABSTRACT FROM AUTHOR]

In this work, the toxicological assessment towards filamentous fungi (Penicilliumsp.) as model eukaryotic organisms of sixteen ionic liquids (containing an imidazolium, pyridinium, or cholinium cation) is presented. Amongst these fungi are members which show much higher tolerance towards ionic liquids than any other microorganism so far studied. Furthermore, guided by the paradigm that the choice of an ionic liquid as catalyst can alter the outcome of a given chemical reaction, the ability of ionic liquids to alter the metabolic profile in fungi was studied. The metabolic footprint, as investigated by electrospray ionisation mass spectrometry, revealed that fungal cultures respond to specific ionic liquids by changing their cell biochemistry, resulting in an altered pattern of secondary metabolites. [ABSTRACT FROM AUTHOR]

A palladium-catalyzed amination oxidation of electron-rich olefins with anilines under air at room temperature in ionic liquids was accomplished. Herein, H2O2 serves as the oxidant and the oxygen source of the carbonyl group. Notably, this new approach provides a practical and straightforward route to access a broad range of privileged amino acid structures with good yields and excellent regioselectivities. Significantly, internal olefins were also compatible with this transformation. [ABSTRACT FROM AUTHOR]

Millions of tons of solvents are consumed annually in various industrial sectors, such as pharmaceuticals, chemical synthesis, textiles, coatings, paints, and others. Ionic liquids (ILs) are pairs of ions in the liquid form synthesized at temperatures below 100 °C that meet specific demands of processes, replacing organic solvents that are harmful to the environment. They offer exceptional prospects as advanced solvents owing to their unique attributes and remarkable recyclability. However, alkyl imidazolium-based ILs have proven to be flammable when exposed to heat, and cytotoxicity and phytotoxicity were observed for many traditional ILs. Therefore, with a focus on negligible toxicity, biocompatibility, straightforward preparation, and sustainability, biocompatible ionic liquids (Bio-ILs) have emerged with huge potential in many different fields of chemistry. These solvents are specifically designed to be derived from naturally occurring compounds. Their physical–chemical properties, modulated according to the application, make them an attractive green technology. Therefore, this review addresses the recent advances in Bio-ILs that include the production of renewable commodities and approaches in catalysis and the pharmaceutical field. Likewise, patents and future perspectives are discussed, demonstrating the great potential of Bio-ILs as green and sustainable compounds. [ABSTRACT FROM AUTHOR]

The separation of structurally similar compounds, such as cholic acid (CA) and deoxycholic acid (DCA), is challenging due to their nearly identical physicochemical properties. This study demonstrates a synergistic 'push and pull' strategy with an ionic liquid (IL) biphasic system for significantly enhanced CA/DCA separation efficiency. Ethyl acetate was selected as the feed solvent to 'push' CA into the IL-rich extractant phase, while the IL 1-ethyl-3-methylimidazolium chloride ([EMIM]Cl) was chosen to 'pull' CA due to their strong hydrogen bonding interaction. This 'push and pull' system yielded a remarkable CA/DCA selectivity up to 47.8, much higher than the case using n-butanol which pulls both CA and DCA. The underlying separation mechanism was elucidated through computational screening with COSMO-RS, NMR analysis, and solvatochromic measurements. Results revealed the critical roles of specific hydrogen bonding between the chloride anion of [EMIM]Cl and the hydroxyl/carboxyl groups of CA/DCA, along with nonspecific interactions between the feed solvent and CA/DCA. Thermodynamic analysis of the phase transfer process confirmed the 'push and pull' synergy is energetically favorable for preferentially transferring CA from the ethyl acetate feed solution into the IL-rich extractant phase. Multi-stage simulation indicated that 99% purity and recovery of both CA and DCA can be obtained through this biphasic system under optimized conditions. Overall, strategically tuning both the feed solvent and IL extractant could significantly enhance the separation efficiency of structurally similar compounds while minimizing solvent and energy consumption. This 'push and pull' approach may shed light on improving separation processes for other structural analogues. [ABSTRACT FROM AUTHOR]

Environmentally open applications as herbicides or active pharmaceutical ingredients are discussed for ionic liquids (ILs). Since most of the ILs are not readily biodegradable in the environment, they may persist there. To prevent the accumulation of persistent and toxic ILs, both the cation and anion need to be designed to completely mineralise in the environment. Several studies summarised structure–biodegradability relationships (SBRs) and gained rules of thumb for ILs' biodegradability based on the available literature data. However, no study systematically analysed a dataset using an in silico tool. Therefore, to identify SBRs a dataset on the ready biodegradability of 508 ILs was clustered according to IL similarity by using the software Canvas by Schrödinger. The biodegradability was divided into three classes (biodegradation rates 0–19%, 20–59% and ≥60%). The identified SBRs were compared with the available rules of thumb from the literature. The results show that the cholinium cation and its derivatives acetylcholine, betaine and carnitine are promising candidates for designing environmentally mineralising ILs if a good biodegradable anion is chosen. Imidazolium and phosphonium ILs should be avoided. For pyrrolidinium and quaternary ammonium compounds cations containing ester or carboxyl groups in side chains and alkylsulphate anions should be tested to close gaps in SBRs and possibly design a mineralising IL. Due to the limited data of morpholinium, 1,4-diazabicyclo[2.2.2]octanium (DABCO), piperidinium, prolinium, piperazinium and thiazolium ILs, SBRs could not be clearly identified. Further research is needed on whether structural adjustments according to the findings can increase the biodegradability of not yet fully degrading (20–59%) ILs. [ABSTRACT FROM AUTHOR]

Shaping cellulose into functional materials entered a new era with the introduction of ionic liquids as novel, green solvents about 20 years ago. As non-volatile solvents with high thermal and chemical stability, ionic liquids can provide an environmentally more benign tunable platform for cellulose processing, compared to existing technologies. The past decades have seen fruitful efforts devoted to the development of materials based on ionic liquid/cellulose processing systems. In this review we discuss the experiences gained, and highlight the emerging applications. In particular, coatings and thin film applications for structural materials (e.g., for packaging), thin film filtration membranes, immobilisation of enzymes, and catalytically active nanoparticles, separator membranes and conductive composites for energy storage and other electronics applications, cellulose/biopolymer green biocomposites, cellulose-based ionogels, hydrogels and aerogels, and cellulose-based or composite fibres will be discussed in detail. We will also take a critical look at the perspectives of this field. The use of a certain grade of technical cellulose, and the purity of the prepared materials should be more carefully justified in the future, as they have an influence not only on the properties of the fabricated material, but also on the economics of the process. Furthermore, to make ionic liquids truly green solvents, and competitive alternatives to existing technologies, more studies are needed on recyclability after material fabrication, and on ways to minimise the energy consumption of such processes, among other issues. [ABSTRACT FROM AUTHOR]

The valorization of abundant agrowastes into chemicals and advanced materials is of key importance in the context of the circular bioeconomy and biorefinery. Herein, we report the ionothermal carbonization (ITC) of sugarcane bagasse, a fibrous residue made of lignocellulose, to engineer advanced carbonaceous materials, namely ionochars. We prepared a series of imidazolium tetrachloroferrate ionic liquids (IL) bearing modular substituents, e.g., alkyl chains with different lengths or benzyl groups. The effect of the cation on both textural and morphological properties is highlighted. Ionochars with high specific surface area (up to 800 m2 g−1), tuneable pore volume (up to 0.8 cm3 g−1), singular nanostructures and adjustable CO2 uptake/retention were obtained. [ABSTRACT FROM AUTHOR]

The establishment of the place of Deep Eutectic Solvents (DESs) as a new class of green solvents was essentially grounded on naïve comparisons with Ionic Liquids (ILs), since both are composed of charged compounds. The easiness of DESs' preparation afforded the quick preparation and utilization of a massive number of solvents and their use in wide variety of applications with minimal fundamental knowledge of their thermophysical properties and phase equilibria studies. As time went on, the need to define DESs from the thermodynamic point of view and to differentiate them from other classes of solvents was imperative. This perspective review aims at dispelling some myths about DESs through the use of experimental data and computational chemical calculations and establishing fair comparisons with other classes of solvents, ILs, eutectic solvents (ESs) and volatile organic compounds (VOCs), so that clear and sound conclusions can be drawn. Several important parameters typically used to characterize solvents and that have been much used to justify DESs' wide range of applications, such as vapor pressure, thermal stability, polarity, toxicity and water miscibility, were accessed for these different solvents and comparisons were established. Moreover, a comparative analysis in a selected research area, biopolymer dissolution and treatment, was chosen to illustrate the unique potential of ILs and DESs and the challenges that still need to be addressed. Literature available for the diverse polysaccharides selected (cellulose, hemicellulose and chitin) and lignin highlighted pros and cons and the different level of knowledge gained to date for both ILs and DESs. This part is complemented by recycling and techno-economic considerations for the two classes of solvents, which are additional key aspects to consider for the development of an effective integrated biorefinery process. The conclusion is obvious: DESs are a new class of solvents, with distinct properties from other classes of solvents which are essentially dependent on the properties of their constituent compounds. Therefore, when starting compounds are wisely selected, DESs become an additional and promising pathway in the pursuit of environmentally friendly solvents to replace traditional VOCs for a given application. However, some fundamental studies are still needed to fully understand these systems and define their most effective areas of application. [ABSTRACT FROM AUTHOR]

Millions of tons of solvents are produced annually and are ubiquitous across many industries ranging from coatings, paintings, textiles, pharmaceuticals, extraction of resources, to chemical synthesis. The global market for solvents is projected to rise as solution processes are typically safer, more efficient, and easier to handle on an industrial scale. Therefore, the search and use of greener solvents are fundamental to our endeavour for a sustainable future. Ionic liquids (ILs) present exciting opportunities as next-generation solvents due to their designer characteristics and high recyclability. However, concerns remain around their toxicity and biocompatibility, and the cost of production is often high due to the low atom economy. Recently, ILs derived from biomolecules have emerged as biocompatible solvents with negligible toxicity and straightforward preparation. Choline amino acid ILs (ChAAILs) are a representative family of biocompatible ILs. They exhibit anion-controlled solvent properties and have been extensively studied for applications including biomass processing and CO2 capture. This review discusses the structure–property relationships of ChAAILs and their mixtures, especially with water. This lays the foundation for the rational design of ChAAIL-based solvent systems with optimised physical properties and reduced costs for specific applications. [ABSTRACT FROM AUTHOR]

Flow chemistry technology innovatively integrates the traditional independent experimental operation processes, speeds up reaction rates and, especially, can be applied in special reactions that are hazardous or under difficult reaction conditions, being beneficial for the development of green chemistry and laboratory automation. In flow chemistry, the application of traditional pipeline microreactors is usually limited by blockage, corrosion and difficult maintenance. The micro/nanomaterials-based microreactors for flow chemistry are supposed to solve these problems. Herein, we report a novel solid–liquid composite microreactor (BiOBr@ILG-microspheres) with ionic liquid compartments based on ionic liquid gel microspheres (ILG-microspheres) and a typical photocatalyst, BiOBr. The BiOBr@ILG-microspheres show high photodegradation performance, which is attributed to the enrichment of organic substrates by the ILG-microspheres, the efficient charge transfer microenvironment of the internal ionic liquids (ILs), and the flower-like heterostructure of the microspheres that hosts abundant active sites. Furthermore, the BiOBr@ILG-microspheres are embedded in a poly(vinyl alcohol) (PVA) hydrogel to build a multi-liquid phase membrane, which exhibits promising performance in removing pollutants continuously from flowing water with an ∼100% removal rate of ciprofloxacin for a long time, due to the synergic effect of the enrichment and catalytic degradation of the pollutants by the BiOBr@ILG-microspheres. This work provides a new research strategy for constructing liquid compartment microreactors with a synergistic effect of extraction–catalysis using the novel developed ILG-microspheres, which will attract widespread interest because it is in accordance with the concept of green chemistry. [ABSTRACT FROM AUTHOR]

Thermal energy storage systems utilising phase change materials have the potential to overcome the intermittency issues associated with most renewable energy sources, significantly contributing to the decarbonisation of the energy sector. While the concept of storing energy in the latent heat of a phase transition is not new, large scale systems employing this concept have not yet realised their full potential. This is in large part due to the shortcomings of conventionally used materials – whether it be issues with their flammability, chemical and thermal instability, corrosivity, poor cycling stability, or a combination of these. Ionic liquids offer a suite of inherent "green" properties that translate well into the field of phase change materials, namely low volatility, low flammability, and good thermal and chemical stability, alongside the potential to tune their chemical and phase properties. In this Perspective, we discuss the evolution and promise of the emerging field of ionic liquids for renewable thermal energy storage. Systems are considered from a holistic, sustainable point of view, demonstrating the importance of assessing material origins and synthetic pathways as well as system performance through lifecycle assessment. We elucidate the emerging design rules for optimising thermal properties, and in doing so attempt to provide an overview of promising emerging systems and future directions. [ABSTRACT FROM AUTHOR]

This perspective reviews the current status and prospects of biocatalysis in ionic liquids. Although they are not strictly speaking ionic liquids, deep eutectic solvents are included because of the close similarities of their properties and potential applications with those of ionic liquids. One consequence of the ongoing transition from an economy based on fossil resources to a circular economy based on renewable biomass is the burgeoning interest in the use of biocatalysis for the selective conversion of carbohydrates and triglycerides to liquid fuels and chemicals in biorefineries. The use of inexpensive, environmentally attractive ionic liquids as solvents, in the pre-treatment and subsequent biocatalytic conversions, for example, is expected to play an important enabling role in this process. [ABSTRACT FROM AUTHOR]

Device-level applications of organic electrolytes unavoidably imply extensive contact with the environment. Despite their excellent scientific potential, ionic liquids (ILs) cannot be approved for practical usage until their life cycle and impact on the environment are assessed. In this work, we carried out the first large-scale study on the mechanisms of the cytotoxic action of various classes of ionic liquids, including imidazolium, pyridinium, pyrrolidinium, ammonium, and cholinium ILs (25 in total). We determined the biological effect of these ILs in seven cell lines of various origins (HEK293 (human embryonic kidney), U937 (human myeloid leukemia), Jurkat (human T-cell leukemia), HL60 (human acute promyelocytic leukemia), K562 (human chronic myelogenous leukemia), A549 (human alveolar adenocarcinoma), and A2780 (human ovarian carcinoma)). The induction of apoptosis in cells upon treatment with the majority of the ILs tested was subsequently demonstrated. The new data suggest that ILs trigger the mitochondrial pathway of apoptosis due to the dissipation of the mitochondrial membrane potential and release of cytochrome c from mitochondria into the cytoplasm. The obtained results corroborate the earlier reported data on the cytotoxic effects of ILs, providing new insight into the detailed mechanisms of IL cytotoxicity. In addition, the first illustrative guide to be employed for designing ILs with targeted biological activity is compiled. As a possible link between the electrochemical behavior of ILs and their biological activity, the relationship between IL cytotoxicity and the electrophoretic mobility of IL cations is assessed. [ABSTRACT FROM AUTHOR]

Various solvents such as ionic liquids, deep eutectic solvents, and aqueous two phase systems have been suggested as greener alternatives to existing extraction processes. We propose to add macroscopic complex coacervates to this list. Complex coacervates are liquid-like forms of polyion condensates and consist of a complex of oppositely charged polyions and water. Previous research focussing on the biological significance of these polyion-rich phases has shown that polyion condensates have the ability to extract certain solutes from water and back-extract them by changing parameters such as ionic strength and pH. In this study, we present the distribution coefficients of five commonly used industrial chemicals, namely lactic acid, butanol, and three types of lipase enzymes in poly(ethylenimine)/poly(acrylic acid) complex coacervates. It was found that the distribution coefficients can vary strongly upon variation of tunable parameters such as polyion ratio, ionic strength, polyion and compound concentrations, and temperature. Distribution coefficients ranged from approximately 2 to 50 depending on the tuning of the system parameters. It was also demonstrated that a temperature-swing extraction is possible, with back-extraction of butanol from complex coacervates with a recovery of 21.1%, demonstrating their potential as extraction media. [ABSTRACT FROM AUTHOR]

Recyclable biocatalysts and high-efficiency lignocellulose deconstruction are the crucial factors for cost-effective conversion of biomass into biofuels and bioproducts. Acetic acid-based catalytic hydrolysis of grassy lignocellulosic biomass presents a promising application because of its effectivity, recyclability, and other environmentally friendly features. However, this treatment is not as effective on woody biomass, such as poplar. One way to improve conversion performance of this process is to integrate it with other effective processes, such as pretreating biomass with protic ionic liquids (PILs) that have been shown to effectively solubilize lignin in reducing the recalcitrance of biomass to enzymatic deconstruction. In this work, an integrated acetic acid based one-pot ethanolamine acetate pretreatment (HAc–[EOA][OAc]) was developed for the efficient depolymerization of poplar polysaccharides. The configuration simultaneously removed ∼88% hemicellulose and selectively extracted up to ∼46% of the lignin from lignocellulosic biomass. HAc–[EOA][OAc] pretreated poplar yielded over 80% enzyme-hydrolyzed glucose that was attributed to an increase in the accessible surface area of cellulose to the hydrolytic enzymes. Analysis of the cellulose crystallinity and thermal decomposition profiles revealed that all pretreated samples have a higher cellulose crystallinity, indicating that amorphous cellulose had been removed during pretreatment. Conductor like screening model for real solvents (COSMO-RS) and Hansen solubility parameters (HSP) were used to provide insights into the mechanism of biomass pretreatment efficacy using both HAc and [EOA][OAc]. We found that a strong hydrogen-bonding and electrostatic misfit interaction between hemicellulose and HAc may explain the higher removal of hemicellulose during HAc pretreatment. Further, the close HSP values and COSMO-RS analysis indicate that [EOA][OAc] is a good lignin solvent, which leads to the higher delignification of biomass. This study demonstrates that the integration of IL with acid pretreatment is a promising strategy for conducting effective pretreatment on woody lignocellulose. [ABSTRACT FROM AUTHOR]

Ionic liquids (ILs) have been labeled as a promising green alternative to traditional materials; however, many ILs have been discovered to be toxic, especially hydrophobic ILs (HILs). HILs are limited in their structural diversity as most are composed of heteroaromatic cations with long alkyl chains and paired with [BF4], [PF6], or [NTf2] anions. This study aims to diversify HILs by synthesizing two sets of HILs with unique cations and anions. The first set of HILs contain cholinium- and dicholinium-based cations paired with the [NTf2] anion. The [DC-ether] cation is identified as a promising cation and is paired with an array of asymmetric bis(sulfonyl)amide anions to form the second set of HILs. In total, twenty HILs are synthesized. Each HIL is characterized using traditional physicochemical techniques and is evaluted for toxicity using in vitro and in vivo methods. [ABSTRACT FROM AUTHOR]

Rare earth metals (REMs) are considered critical materials due to their extensive demand for use in essential technologies that enable the transition to a greener energy technology and economy. However, the significant environmental and health impact caused by the current primary sourcing of REMs, i.e. mining, urgently demand more sustainable and environmentally friendly alternatives. Herein we report a cleaner approach to recover Nd via electrochemical deposition using low cost and non-fluorinated ionic liquid (IL). In contrast to most typically studied ILs utilising the bis(trifluoromethanesulfonyl)imide anion, here we show successful electrodeposition of Nd using 0.5 mol kg−1 neodymium nitrate (Nd(NO3)·6H2O) in N-butyl-N-methylpyrrolidinium dicyanamide ([C4mpyr][DCA]) IL electrolyte while reporting an eight times higher current density (−38 mA cm−2) at a lower temperature (halved to 50 °C) and less controlled environment (0.15–4.6 wt% H2O) compared to parameters previously reported in the literature. Further, the effect of Nd salts and their concentration on the electrolyte physical properties, Nd3+ electrochemical behaviour, electrodeposit composition and Nd recovery efficiency were investigated using Nd(OTf)3 (trifluoromethanesulfonate [OTf]−) and Nd(NO3)·6H2O in [C4mpyr][DCA] IL electrolytes. The XPS analysis confirmed the presence of a higher Nd metal content in the electrodeposit resulting from the nitrate system. [ABSTRACT FROM AUTHOR]

Ionic liquids (ILs) have been used as solvents or materials, or both, in many applications, including pharmaceutics and medicine due to their exceptional properties consisting of the combination of "green" properties with tunable physicochemical and biological properties. The use of ILs in the pharmaceutical industry can address many challenges associated with the use of conventional organic solvents or water. ILs have been established as potential solvents to solubilize many insoluble or sparingly soluble drugs for formulations or delivery. The use of ILs can also address many of the drawbacks of solid-state drugs, including polymorphism and low solubility, stability, and bioavailability. However, many ILs are inherently toxic, which is the main challenge toward developing IL-based drug formulations and drug delivery systems. The use of second- and third-generation ILs comprising more biocompatible cations and anions, compared with the first-generation ILs, has considerably addressed the toxicity issue. A wide range of biocompatible ILs have been designed to improve the pharmacokinetic and pharmacodynamic properties, as well as the biological activity, of drugs. This review describes the advances in the area of green IL-related research and emphasizes the new conceptual development of ILs in pharmaceutics and medicine. Particular attention is given to the mechanistic knowledge in the synthesis of ILs, as well as to the ecotoxicological and biological impact of biocompatible ILs, stimulating the understanding of innovative technologies in IL-based drug delivery systems. [ABSTRACT FROM AUTHOR]

Ionic liquids (ILs) are remarkable green solvents, which find applications in many areas of nano- and biotechnology including extraction and purification of value-added compounds or fine chemicals. These liquid salts possess versatile solvation properties that can be tuned by modifications in the cation or anion structure. So far, in contrast to the great success of theoretical and computational methodologies applied to other fields, only a few IL models have been able to bring insights towards the rational design of such solvents. In this work, we develop coarse-grained (CG) models for imidazolium-based ILs using a new version of the Martini force field. The model is able to reproduce the main structural properties of pure ILs, including spatial heterogeneity and global densities over a wide range of temperatures. More importantly, given the high intermolecular compatibility of the Martini force field, this new IL CG model opens the possibility of large-scale simulations of liquid–liquid extraction experiments. As examples, we show two applications, namely the extraction of aromatic molecules from a petroleum oil model and the extraction of omega-3 polyunsaturated fatty acids from a fish oil model. In semi-quantitative agreement with the experiments, we show how the extraction capacity and selectivity of the IL could be affected by the cation chain length or addition of co-solvents. [ABSTRACT FROM AUTHOR]

A palladium-catalyzed ionic liquid-accelerated oxidative cascade annulation/functionalization of acetylenic oximes with unactivated long-chain enols under aerobic conditions was accomplished. This newly developed protocol provides the rapid and straightforward synthetic strategy for the assembly of structurally diverse isoxazole architectures under mild conditions with high atom- and step-economy and exceptional functional group tolerance. Notably, the ionic liquid acts as not only a solvent in the reaction but also provides the excess halide ions to eliminate hydrochloride from acetylenic oximes. Moreover, this catalytic system could be recycled up to eight times and reused without significant loss of the catalytic activity. [ABSTRACT FROM AUTHOR]

Ionic liquids (ILs) are perceived as a promising group of chemicals within the realm of green chemistry. They are increasingly of interest for open environmental applications. Rules for the design of biodegradable and preferably completely mineralizing ILs after their introduction into the environment are highly desirable. In this study, the impact of the length of the alkyl chain and of the cationic head group on the environmental biodegradability of L -phenylalanine ester (PheCn) derived ILs using the pyridinium (PyPheCn), imidazolium (ImPheCn) and cholinium (CholPheCn) head groups was systematically studied. This included high-resolution mass spectrometry monitoring of formed products of incomplete mineralization. Completely biodegradable ILs were only identified in the PyPheCn series. PyPheC2 and PyPheC4 were fully mineralizable within 42 days with no detectable transformation products (TPs), whereas mineralization of longer chain length PyPheCn ILs required more time. Our results show biodegradation by microorganisms was affected by an alkyl chain length of at least 10 carbon atoms. Biodegradation of the ILs started with biotic ester hydrolysis independent of the alkyl chain length or core scaffold. In contrast, the second step of microbial degradation was an amide bond cleavage which was only shown for ILs with a pyridinium or imidazolium core, even after a test prolongation up to 42 days. Hence, the nature of the cationic head group and the chain length impacted on the mineralization and biodegradability of the ILs. For ILs with an imidazolium core, amide bond cleavage resulted in the formation of recalcitrant 1-carboxymethylimidazolium (ImAc). Whereas for most ILs with a pyridinium core, amide bond cleavage resulted in 1-carboxymethylpyridinium (PyAc) which was mineralizable, although not readily biodegradable according to the test guideline 301D. In the case of cholinium ILs, no further degradation of cholinium phenylalanine amide TP was observed after the hydrolysis of the ester to the alkyl alcohol. The biodegradability of ILs decreased in the order PyPheCn > ImPheCn > CholPheCn, but a key finding is that ImPhe is degraded to ImAc but not further (cf. favourable PyAc mineralisation). These results can be used to design ILs with the property to be effectively biodegraded and mineralized in the environment. [ABSTRACT FROM AUTHOR]

The theoretical promise of ionic liquids (ILs) as 'green' designer solvents that can be tuned to facilitate key steps of lignocellulosic biomass processing has not been fully realized due to the sheer number of possible cation–anion combinations and concerns about toxicity of this class of chemicals. Although computational methods are being applied to identify ILs with specific functions, such as dissolution of cellulose, they are not used to iteratively design new ionic liquids with the goal of simultaneously optimizing multiple criteria, such as performance and environmental safety. Here we describe a tiered computational approach to develop new ILs based on mixed quantum and molecular mechanics simulations, which, combined with analysis of physicochemical properties of ILs can be used to guide structural modifications to design both better performing task-specific and safer IL analogs. The increase in computing requirements of the proposed approach over structure-based statistical models is relatively modest; yet, our approach is more robust than these models, and far less costly than highly-accurate but very demanding large-scale molecular simulations. [ABSTRACT FROM AUTHOR]

Glycolysis of poly(ethylene terephthalate) (PET) is a prospective way for degradation of PET to its monomer bis(hydroxyethyl) terephthalate (BHET) which can be polymerized again to form new qualified PET materials, and hence provides possibilities for a permanent loop recycling. However, most of the reported glycolysis catalysts are metal-based, leading to high cost and negative environmental impact. In this study, we developed a series of choline-based ionic liquids (ILs) without metals and applied them in the glycolysis of PET as catalysts. Choline acetate ([Ch][OAc]), which is cheaper, more biologically compatible and environmentally friendly in comparison with conventional imidazolium metal-based ILs, can achieve a comparable or even better performance than them. Under optimum conditions (PET (5.0 g), ethylene glycol (EG) (20.0 g), [Ch][OAc] (5 wt%), 180 °C, 4 h, atmospheric pressure), the yield of BHET reached up to 85.2%. Additionally, the reaction kinetics was studied and proved to be the shrinking-core model. The apparent activation energy is 131.31 kJ mol−1, and the pre-exponential factor is 1.21 × 1013 min−1. Finally, based on the experimental results and density functional theory (DFT) calculations, a possible mechanism was proposed. The promotion of the glycolysis reaction is attributed to the activation of EG by the formation of hydrogen bonds between EG and the IL. [ABSTRACT FROM AUTHOR]

Recently, the utilization of starch to replace synthetic polymers for the manufacture of green materials has gained extensive interest, due to its renewability, biodegradability, abundance and low cost. On the other hand, ionic liquids (ILs) have been widely recognized as promising "green solvents" to replace volatile organic solvents for polysaccharide processing. Over the past few years, ILs have been increasingly demonstrated to serve as excellent media for the dissolution, plasticization and derivatization of starch. This allows the synthesis of chemically modified starches with high degree of substitution (DS) and the development of various starch-based materials such as thermoplastic starch, composite films, solid polymer electrolytes, nanoparticles and drug carriers. The main objective of this review is to present an overview of the roles of ILs in starch dissolution, gelatinization, modification and plasticization, and their industrial applications. Moreover, this review is intended to provide a comprehensive understanding of the mechanisms behind the IL-processing of starch and to provide insights into the rational development of novel starch-based materials with ILs. [ABSTRACT FROM AUTHOR]

This manuscript describes the first electrosynthesis of biobased ionic liquids from L -valine, oxalic acid and glyoxal, which is energy-efficient, does not emit toxic waste and avoids the formation of inorganic waste. These ionic liquids were then used in the development of our electro-recycling process. While their recycling yields are still moderated due to recombination and disproportionation reactions, this unprecedented recycling technology is very promising in terms of environmental and economic gains. Indeed, it has a high energy efficiency, requires low cost equipment, allows a strong decrease of the price of such ionic solvents, limits the use of non-renewable resources and solves the end-of-life problem of dirty biobased ionic liquids. [ABSTRACT FROM AUTHOR]

Monoclonal antibodies (mAbs) are of crucial interest for therapeutic purposes, particularly in vaccination and immunization, and in the treatment of life-threatening diseases. However, their downstream processing from the complex cell culture media in which they are produced still requires multiple steps, making mAbs extremely high-cost products. Therefore, the development of cost-effective, sustainable and biocompatible purification strategies for mAbs is in high demand to decrease the associated economic, environmental and health burdens. Herein, novel aqueous biphasic systems (ABS) composed of glycine–betaine analogue ionic liquids (AGB-ILs) and K2HPO4/KH2PO4 at pH 7.0, the respective three-phase partitioning (TPP) systems, and hybrid processes combined with ultrafiltration were investigated and compared in terms of performance as alternative strategies for the purification and recovery of anti-human interleukin-8 (anti-IL-8) mAbs, which are specific therapeutics in the treatment of inflammatory diseases, from Chinese Hamster Ovary (CHO) cell culture supernatants. With the studied ABS, mAbs preferentially partition to the IL-rich phase, with recovery yields up to 100% and purification factors up to 1.6. The best systems were optimized in what concerns the IL concentration, allowing to take advantage of IL-based three-phase partitioning approaches where a precipitate enriched in mAbs is obtained at the ABS interface, yielding 41.0% of IgG with a purification factor of 2.7 (purity of 60.9%). Hybrid processes combining the two previous techniques and an ultrafiltration step were finally applied, allowing the recovery of mAbs from the different fractions in an appropriate buffer solution for further biopharmaceutical formulations, while allowing the simultaneous IL removal and reuse. The best results were obtained with the hybrid process combining TPP and ultrafiltration, allowing to obtain mAbs with a purity higher than 60%. The recyclability of the IL was additionally demonstrated, revealing no losses in the purification and recovery performance of these systems for mAbs. The biological activity of anti-IL-8 mAbs is maintained after the several purification and recovery steps, indicating that the novel ABS, three-phase partitioning and hybrid processes comprising AGB-ILs are promising and sustainable strategies in mAbs downstream processing. [ABSTRACT FROM AUTHOR]

The abundance and unique characteristics of keratin containing natural protein fibres such as wool and silk suggest their use as an alternative to certain petroleum based polymers. Among keratin containing resources, human hair is one of the most abundant keratin rich natural fibres and is one of the most plentiful waste materials produced by human beings. It has been estimated that about 300 000 tons of hair are thrown away per annum in the world. Keratin can be produced from waste human hair (WHH) in a cost effective way and can be utilized in the preparation of biomaterials. Due to the excellent solvation properties of ionic liquids (ILs), the solubility of WHH was investigated in various hydrated ILs (HILs). Among the HILs, tetrabutylammonium hydroxide (TBAH, 40% aqueous solution) is found to completely solubilise 25% w/w of WHH. Melanin and keratin with 20–22% and 36–38% yield were isolated from the solution and due to the very good nitrogen content (6.99%) in the HIL remaining after the isolation (39–40%), it can be used to fortify nitrogen deficient liquid seaweed fertilizers for agriculture applications. The biorefinery concept presented herein is found to be suitable for up scaling. [ABSTRACT FROM AUTHOR]

We report for the first time a comprehensive study on the synthesis (supported by green chemistry metrics), aggregation properties, bacterial/fungal toxicities and preliminary data on biodegradation of a series of 24 l-phenylalanine derived surface-active ionic liquids (SAILs). The various cationic headgroups included pyridinium, imidazolium, and cholinium groups and enabled a comprehensive analysis of the effect of the alkyl ester chain (from C2 to C16) on the synthesis, toxicity, biodegradability, and surfactant properties of the novel SAILs. The evaluation of the SAILs revealed that a wide variety of properties were strictly dependent on the side chain length, including their bacterial and fungal toxicities (from low toxicity to high toxicity), and aggregation properties. Addition of the l-phenylalanine moiety which connects the lipophilic side chain to the cationic head group results in the phenyl group essentially contributing to the self-assembling properties. The interplay of dispersion interactions of the phenyl ring and the side chain hydrophobicity allows us to rank the novel SAILs (thus identifying the remarkable ones) as compared to other surfactants. The CMC values for the SAILs reported in this study are significantly (up to 10 times) lower than those reported for conventional surfactants with the same length of the side chain. Adsorption and micellization are among the factors affecting the toxicity of the studied SAILs. Preliminary biodegradation studies have shown that no clear trend was observed when comparing the closed bottle test results of the SAIL C2 and C10 derivatives. Medium chain length (C6 to C8) pyridinium SAILs have been recommended as the most prospective green alternatives for conventional cationic surfactants. These findings can contribute to designing new efficient amphiphiles with optimized antimicrobial activities and to employ them as potential environmentally benign mineralisable surfactants. [ABSTRACT FROM AUTHOR]

Catalytic fixation of CO2 to produce valuable fine chemicals is of great significance to develop a green and sustainable circulation of excessive carbon in the environment. Herein, a series of non-toxic, biodegradable and recyclable acetylcholine-carboxylate bio-ionic liquids with different cations and anions were simply synthesized for producing formamides and methylamines using atmospheric CO2 as a carbon source, and phenylsilane as a hydrogen donor. The selectivity toward products was tuned by altering the reaction temperature under solvent or solvent-free conditions. N-Methylamines (ca. 96% yield) were obtained in acetonitrile at 50 °C, while N-formamides (ca. 99% yield) were attained without a solvent at 30 °C. The established bio-ionic liquid catalytic system found a wide range of applicability in substrates and possessed a high potentiality in scale-up to gram-grade production. The developed catalytic system was fairly stable, which could be easily reused without an apparent loss of reactivity, possibly due to the strong electrostatic interactions between the cation and anion. The combination of experimental and computational results explicitly elucidated the reaction mechanism: PhSiH3 activated by a bio-IL was favorable for the formation of silyl formate from hydrosilylation of CO2, followed by a reaction with an amine to give an N-formamide, while an N-methylamine was formed by further hydrosilylation of the N-formamide. [ABSTRACT FROM AUTHOR]

Low yields commonly obtained during enzymatic conversion of CO2 to methanol are attributed to low CO2 solubility in water. In this study, four selected ionic liquids with high CO2 solubility were separately added to the multi-enzyme reaction mixture and the yields were compared to the pure aqueous system (control). In an aqueous 20% [CH][Glu] system, yield increased ca. 3.5-fold compared to the control (ca. 5-fold if NADH regeneration was incorporated). Molecular dynamics simulation revealed that CO2 remains for longer in a productive conformation in the enzyme in the presence of [CH][Glu], which explains the marked increase of yield that was also confirmed by isothermal titration calorimetry – lower energy (ΔG) binding of CO2 to FDH. The results suggest that the accessibility of CO2 to the enzyme active site depends on the absence/presence and nature of the ionic liquid, and that the enzyme conformation determines CO2 retention and hence final conversion. [ABSTRACT FROM AUTHOR]

It is well-known that for a fixed ionic liquid cation, variation of the anion determines the physicochemical properties and the activity as solvent or catalyst. Although ion exchange is an acknowledged phenomenon, it is often overlooked in ionic liquid applications due to a lacking framework. We propose here a framework to describe and predict ionic liquid ion exchange with a gain in interaction energy as driving force. The low charge density ionic liquid cations display low interaction energies and are condemned to pair with the most weakly interacting anions in the system, after all stronger interactions have formed. This is demonstrated both for phosphonium and imidazolium ionic liquids, with and without hydration effects. The importance on processing is exemplified by esterification, in which the degree of exchange of carboxylic acid for carboxylate and the availability of protons determines the conversion. [ABSTRACT FROM AUTHOR]

Aiming at designing effective and sustainable separation processes, herein we propose the use of carbohydrates combined with tetraalkylphosphonium- or tetraalkylammonium-based ionic liquids (ILs) to form aqueous biphasic systems (ABS). The formation of ABS composed of non-aromatic and non-fluorinated ILs with carbohydrates is shown here for the first time. These novel systems are competitive extraction platforms when compared against more conventional ABS formed by ILs and salts or fluorinated ILs and carbohydrates. Finally, it is shown that these systems can be efficiently recovered and reused, without losses in their separation performance. [ABSTRACT FROM AUTHOR]

The recovery of indium from a crude indium(iii) hydroxide using the ionic liquid betainium bis(trifluoromethylsulfonyl)imide, [Hbet][Tf2N], was investigated. Leaching and solvent extraction were combined in one step using the thermomorphic properties of the [Hbet][Tf2N]–H2O system. During leaching (80 °C) a homogeneous phase was formed. Upon lowering the temperature below the lower critical solution temperature (UCST), the dissolved metals distributed themselves between the two phases. The optimal leaching/extraction conditions were determined to be a leaching time of 3 hours at 80 °C in a 1 : 1 wt/wt [Hbet][Tf2N]–H2O mixture. Large separation factors (＞100) between In(iii) and Al(iii), Ca(ii), Cd(ii), Ni(ii) and Zn(ii) were obtained implying an easy separation. Fe(iii), As(v) and Pb(ii) are co-extracted. The separation factor between indium and iron was improved to ＞1000 by addition of ascorbic acid to reduce Fe(iii) to Fe(ii). The stripping was done very efficiently by HCl solution. The ionic liquid was regenerated during the stripping step. By combining a prehydrolysis and hydrolysis step, indium(iii) hydroxide with a purity ＞99% was obtained. [ABSTRACT FROM AUTHOR]

A superbase-derived protic ionic liquid (IL, [DBUH][OAc]) catalyst was used to directly synthesize carbamate from an amine, CO2, and a silicate ester. This IL catalyst was easily prepared using its precursors, DBU, and acetic acid. Using 10 mol% of the catalyst under a CO2 pressure of 5 MPa in acetonitrile at 150 °C, carbamate was isolated in up to 96% yield. Specifically, aliphatic and aromatic amines were activated even though aromatic amines exhibited low activities because of their low pKa values. Other functional groups in amines were barely activated, affording exclusive chemoselectivity for amine activation. Isotope labeling experiments indicated that the proton in the counter cation is crucial in the catalytic cycle to produce water. In addition, a chemical shift corresponding to a mixture of aniline and [DBUH][OAc] was observed in the 1H NMR spectrum, related to the formation of hydrogen bonds between aniline and basic acetate anions. The experimental results indicated that the designed IL catalysts require a protonated cation and a basic anion. [ABSTRACT FROM AUTHOR]

Prior studies of metal ion partitioning between an acidic aqueous phase and an ionic liquid in the presence of a macrocyclic polyether have demonstrated that the overall partitioning is a composite of three distinct pathways: neutral complex/ion-pair extraction, exchange of a cationic metal-crown ether (CE) complex for the cationic constituent of the IL, and exchange of the metal ion for a hydronium ion in a CE-H3O+ complex formed during acid preconditioning of the IL. The obvious undesirability of the ion-exchange pathways, which can lead to substantial loss of the IL cation to the aqueous phase, has led to efforts to identify means by which these processes can be suppressed or eliminated. Prior work with N,N′-dialkylimidazolium and quaternary ammonium bis [(trifluoromethyl)sulfonyl]imides has shown that increasing the hydrophobicity of the IL cation can be an effective means of diminishing the contribution of ion-exchange. Work with the corresponding N-alkylpyridinium ILs, however, indicates that in certain instances, an increase in the hydrophobicity of the IL cation is accompanied by a marked increase in its propensity to self-associate, leading to the formation of micelles in the aqueous phase. The net effect is to diminish or even negate the expected beneficial effect of IL cation hydrophobicity in reducing the contribution of ion exchange to the overall metal ion partitioning process, adversely impacting the “greenness” of extraction processes employing these ILs. [ABSTRACT FROM AUTHOR]

The catalyst in homogeneously catalyzed aminofunctionalizations is often difficult to recycle, making these reactions expensive on an industrial scale. The use of dimethylammonium dimethylcarbamate (dimcarb) as a reactive ionic liquid provides an elegant solution to this challenge, as it is a substrate and polar phase at the same time. In this work, homogeneously transition-metal catalyzed reactions – specifically hydroamination, telomerization and hydroaminomethylation – are carried out in neat substrates without additional solvents. The ionic character of dimcarb enables the immobilization of the active catalysts in the reactive ionic liquid, using sulfonated ligands. Investigations regarding the hydroamination of 1,3-dienes led to a total turnover number (TTON) of more than 8700 with β-farnesene in 12 repetitive recycling experiments. The telomerization of 1,3-butadiene was carried out over 30 consecutive runs without any loss of activity, resulting in a TTON of more than 90 000. [ABSTRACT FROM AUTHOR]

There is considerable interest in the use of structurally stable and catalytically active enzymes, such as cytochrome c (Cyt c), in the pharmaceutical and fine chemicals industries. However, harsh process conditions, such as temperature, pH, and the presence of organic solvents, are the major barrier to the effective use of enzymes in biocatalysis. We demonstrate the suitability of cholinium-based ionic liquids (ILs) formed by the cholinium cation and dicarboxylate-based anions as potential media for enzymes, in which remarkable enhanced activity and improved stability of Cyt c against multiple stresses were obtained. Among the several ILs studied, an exceptionally high catalytic activity (＞50-fold) of Cyt c was observed in the aqueous solutions of cholinium glutarate ([Ch][Glu]; at 1 : 1 weight ratio of IL : H2O) compared to the commonly used phosphate buffer solutions (pH 7.2), and ＞25-fold compared to the aqueous solutions of cholinium dihydrogen phosphate ([Ch][Dhp]; 1 : 2 weight ratio of IL : water)―the best known IL for long term stability of Cyt c. The catalytic activity of the enzyme in the presence of ILs was retained against several external stimuli, such as chemical denaturants (H2O2 and GuHCl) and temperatures of up to 120 °C. The observed enzyme activity is in agreement with its structural stability, as confirmed by UV–vis, circular dichroism (CD), and Fourier transform infrared (FT-IR) spectroscopy. Taking advantage of the multi-ionization states of di/tri-carboxylic acids, the pH was switched from acidic to basic by the addition of the corresponding carboxylic acid and choline hydroxide, respectively. The activity was found to be maximum at a 1 : 1 molar ratio of [Ch][carboxylate], with a pH in the range from 3 to 5.5. Moreover, it was found that the cholinium-based ILs studied herein protect the enzyme against protease digestion and allow long-term storage (at least for 21 weeks) at room temperature. An attempt by molecular docking was also made to better understand the efficacy of the investigated cholinium-based ILs towards the enhanced activity and long term stability of Cyt c. The results showed that dicarboxylate anions interact with the active site's amino acids of the enzyme through H-bonding and electrostatic interactions, which are responsible for the observed enhancement of the catalytic activity. Finally, it is demonstrated that Cyt c can be successfully recovered from the aqueous solution of ILs and reused without compromising its yield, structural integrity and catalytic activity, thereby overcoming the major limitations in the use of IL–protein systems in biocatalysis. [ABSTRACT FROM AUTHOR]

Rare earth elements (REEs) are in high demand as critical materials in modern green and other advanced technologies. This review focuses on the recovery of REEs from waste with ionic liquids (ILs) as green dilutants and extractants to tackle the REE supply challenge. Extraction mechanisms in different extraction systems, including pure ILs, non-functional ILs with extractants, and functional ILs, are discussed in depth. The IL-based extraction process is different from the traditional molecular solvent-based extraction process. In addition, stripping is crucial to recovering ILs, and supercritical CO2 (Sc-CO2) is introduced to recover REE complexes from the IL phase. Also, Sc-CO2 can accelerate the whole extraction process by enhancing mass transfer. The challenge is to understand the extraction mechanism of the IL/Sc-CO2 system to advance the green recovery of REEs from waste. [ABSTRACT FROM AUTHOR]

Fluoroquinolones (FQs) and Non-Steroidal Anti-Inflammatory Drugs (NSAIDs) are two classes of Active Pharmaceutical Ingredients (APIs) in widespread use in human healthcare and as veterinary drugs, and that have been found throughout the water cycle in the past years. These two classes of APIs are commonly present in aqueous streams in concentrations ranging from ng L−1 to μg L−1. Despite such low concentrations, these contaminants tend to bioaccumulate, leading to serious environmental and health issues after chronic exposure. The low concentrations of FQs and NSAIDs in aqueous media also render difficult identification and quantification, which may result in an inefficient evaluation of their environmental impact and persistence. Therefore, the development of alternative pre-treatment techniques for their extraction and preconcentration from aqueous samples is a crucial requirement. In this work, liquid–liquid systems, namely ionic-liquid-based aqueous biphasic systems (IL-based ABS), were tested as simultaneous extraction and preconcentration platforms for FQs and NSAIDs. ABS composed of imidazolium-, ammonium- and phosphonium-based ILs and a citrate-based salt (C6H5K3O7) were evaluated for the single-step extraction and enrichment of three FQs (ciprofloxacin, enrofloxacin and norfloxacin) and three NSAIDs (diclofenac, naproxen and ketoprofen) from aqueous samples. Outstanding one-step extraction efficiencies of APIs close to 100% were obtained. Furthermore, the preconcentration factors of both FQs and NSAIDs were optimized by an appropriate manipulation of the phase-forming components compositions to tailor the volumes of the coexisting phases. Preconcentration factors of 1000-fold of both FQS and NSAIDs were obtained in a single-step process, without reaching the saturation of the IL-rich phase. The preconcentration of APIs up to mg L−1 allowed their easy and straightforward identification and quantification by a High-Performance Liquid Chromatography (HPLC) system coupled to an UV detector, as shown for both model systems (distilled water) and real effluent samples from a wastewater treatment plant. [ABSTRACT FROM AUTHOR]

Expedient alkylations of 1-methyl-3H-imidazole-2-thione, a pharmaceutical active ingredient available in bulk quantities, provide high yield access to numerous protonated, or quaternized imidazoliums with chemospecific attachment of the fluoroponytail at the 2-mercapto functionality. The deprotonated primary target products represent valuable nitrogen heterocyclic bases, capable of further substitution, and salt or complex formation. Specific physicochemical characteristics that are relevant for phase and surface responsive behavior, e.g. critical micelle concentration, oleophobicity, depression of the aqueous surface tension, foam formation, emulsification of microgranular PTFE, are investigated for selected representatives and compared to the properties of common fluorosurfactants and ionic liquids. Remarkably, it is found that halogen bonding between iodide counterions of respective polyfluoroalkylmethimazolium systems and 1-iodoperfluoroalkanes, serving as the σ-hole partner of the halides, greatly affect the solubility profile of the resulting molecular adducts. Single-crystal X-ray structure determinations are carried out across the new fluorous substance classes. Strikingly, the helical arrangement of fluorine atoms along the chains typically encountered in polyfluorinated compounds is not found as the prevailing conformation. Rather, they are outnumbered by structural motifs exhibiting the rare zig-zag (linear alkane-like) chain conformation. Key derivatives are also subjected to preliminary ecotoxicological testing. [ABSTRACT FROM AUTHOR]