Presence Of Ionic Liquid Research Articles

Direct One-Step Controlled Partial Depolymerization and Upcycling of Poly(ethylene terephthalate) into Hyperbranched Oligomeric Ionogel

Chemical recycling of poly(ethylene terephthalate) (PET) by depolymerization into monomers to recreate virgin-grade plastics is desirable; however, the energy-inefficient separation and purification steps needed to obtain high-purity monomers result in poor overall economic feasibility at present. Herein, we present a one-step integrated process for partial depolymerization and upcycling of PET oligomers directly into high-value products without any need for solvent recovery and purification. The key strategy for our approach is using multifunctional cleaving agents such as glycerol in the presence of ionic liquid as a catalyst for controlled partial depolymerization of PET via transesterification using N-methyl-2-pyrrolidone (NMP) as a solvent. The obtained depolymerized, oligomeric PET (DOPET) recyclate together with NMP and IL is a gel-like, ionic-conductive material, also termed as an “ionogel”, that has the potential to be used in energy storage applications or as mechanically robust electrical conductors. This is a one-step process requiring no extensive separation and purification of PET oligomers or distillation of solvent for recovery, which further simplifies the recycling process while simultaneously increasing the value of the waste product. We have further investigated the effects of the choice and amount of cleaving agent on the molecular weight and branching of the DOPET oligomers and hence the properties of the upcycled end products. Moreover, we have also shown the versatility of the abovementioned process for controlled depolymerization of other condensation polymers such as polyamides, polyurethane, and even mixed polymer products to obtain high-value functional materials.

Comparative investigation of artificial neural network and response surface approach in the optimization of indium recovery from discarded LCD screen with the presence of ionic liquids

This paper aimed to predict the solvent extraction conditions to maximize indium recovery from discarded LCD screens. Two approaches, including the response surface methodology (RSM) and the artificial neural network (ANN), were utilized to predict the efficiency of indium recovery. The main parameters, such as aqueous phase acidity (A), indium concentration (B), ionic liquid concentration (C), and aqueous to organic phase ratio (D), were investigated by using CyphosIL 101 diluted in kerosene as the organic phase. The experimental results were used to train a multilayer perceptron for creating an ANN model with the structure of one, eight, and three for input, hidden, and output layers, respectively. The optimum conditions by the RSM approach to provide the maximum efficiency of indium recovery were.4 mol/L A, 197.79 ppm of B, 0.009 mol/L of C, and 1.58 mol/L of D. By contrast, the ANN approaches illustrated the optimal A, B, C and D equal to 4.2, 194.32, 0.0085, and 1.52 %, respectively. Two statistical approaches described the satisfactory data, and the superior data was obtained with the ANN approaches. The use of two ionic liquids verified the indium recovery from the discarded LCD screen, and 99.7 % of indium ions were separated and extracted into the stripping solution.

Designing protein nano-construct in ionic liquid: a boost in efficacy of cytochrome C under stresses.

Herein, we present a simple approach to fabricate protein nanoconstructs by complexing cytochrome C (Cyt C) with silk nanofibrils (SNF) and choline dihydrogen phosphate ionic liquid (IL). The peroxidase activity of the IL modified Cyt C nanoconstruct (Cyt C + SNF + IL) increased significantly (2.5 to 10-fold) over unmodified Cyt C and showed enhanced catalytic activity and stability under harsh conditions, proving its potential as a suitable protein packaging strategy.

Single lithium–ion transport and electrochemical stability triggered by organoborate zwitterions for self-assembled PAS–co–2PEG solid electrolytes for lithium–sulfur battery

Super ion-conductive solid polymeric electrolytes (SPEs) with high lithium (Li)–ion selectivity are applied to develop high efficiency, safe, and long-life lithium–sulfur batteries (LSB). Herein, a high-performance SPE is prepared by employing organoborate zwitterions (ZBo) into the flexible self-assembled poly(arylene ether sulfone) electrolytes grafted with dual poly(ethylene glycol) segments (PAS–co–2PEG) in the presence of ionic liquid. The large dipole moment of steric bulky ZBo present in lithium–ion conductive PEG domains phase separated from mechanically reinforced PAS matrix results in the promotion of Li-salt and borate anion/ Li-cation dissociation to facilitate the Li–ion migrations. The versatile functional groups in ZBo, such as ethyl carbonate (−EC), nitrile (−CN), and PEG with high dielectric constant aids Li-hopping without ionic aggregations. Attributed to these unique features, the as-developed SPEs show not only high thermal and mechanical stability above 250 °C and 1 MPa tensile strength, but also large electrochemical stability window of 5.3 V and high ionic conductivity of 1.05 mS cm−1 along with Li-ion transfer number of ∼0.5. The corresponding S/SPE/Li cells show 99.2 % of capacity retention after 200 cycles at 0.2C rate, demonstrating the promise of the advanced development of all-solid-state LSBs.

CO2 Capture Improvement in Polyetherimide Membranes: Effect of Ionic Liquid on the Molecular Mobility

The research described here was aimed at the development of polymeric membranes based on polyetherimide (PEI) containing the ionic liquid (IL) 1-butyl-2,3-dimethylimidazolium hexafluorophosphate ([BMMIM]PF6). The preparation of the PEI-based membranes was carried out via casting of solutions with the incorporation of the IL. The prepared membranes were characterized by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) for thermal and free volume properties. CO2 sorption and permeation properties were measured to evaluate the CO2 capture performance of the membranes. The fractional free volume (FFV) of the membranes was around 15%. The incorporation of IL increased the CO2 sorption capacity, promoting an increase of 330% in the solubility coefficient (KD) and resulted in a decrease of 96% in CO2 permeability when compared to the control membrane. The presence of IL in the PEI matrix significantly altered the structural and transport characteristics of the analyzed membranes, being efficient for CO2 capture, as they showed a high CO2 solubility and a decrease in CO2 permeation.

Investigation of Sulfonium-Iodide-Based Ionic Liquids to Inhibit Corrosion of API 5L X52 Steel in Different Flow Regimes in Acid Medium.

The present work deals with the corrosion inhibition mechanism of API 5L X52 steel in 1 M H2SO4 employing the ionic liquid (IL) decyl(dimethyl)sulfonium iodide [DDMS+I-]. Such a mechanism was elicited by the polarization resistance (R p), potentiodynamic polarization (PDP), and electrochemical impedance spectroscopy (EIS) techniques, both in stationary and dynamic states. The electrochemical results indicated that the corrosion inhibition was controlled by a charge transfer process and that the IL behaved as a mixed-type corrosion inhibitor (CI) with anodic preference. The experimental results revealed maximal inhibition efficiency (IE) rates up to 93% at 150 ppm in the stationary state, whereas in turbulent flow, the IE fell to 65% due to the formation of microvortexes that promoted higher desorption of IL molecules from the surface. The Gibbs free energy of adsorption (ΔG°ads) value of -34.89 kJ mol-1, obtained through the Langmuir isotherm, indicated the formation of an IL monolayer on the metal surface by combining physisorption and chemisorption. The surface analysis techniques confirmed the presence of Fe x O y , FeOOH, and IL on the surface and showed that corrosion damage diminished in the presence of IL. Furthermore, the quantum chemistry calculations (DFT) indicated that the iodide anion hosted most of the highest occupied molecular orbital (HOMO), which eased its adsorption on the anodic sites, preventing the deposition of sulfate ions on the electrode surface.

Computational investigation of conformational fluctuations of Aβ42 monomers in aqueous ionic liquid mixtures

Aggregation of intrinsically disordered proteins (IDPs) is often triggered by protein–protein interaction, leading to several neurodegenerative diseases.In this study, we aim to understand the role of 1-butyl-3-methylimidazolium tetrafluoroborate [BMIM][BF4] ionic liquid (IL) on altering secondary structure of the peptide and study the interactions responsible for their conformational modification. Here we report structural features of an ensemble of amyloid beta (Aβ42) peptide monomers employing all-atom molecular dynamics simulations in aqueous solution of IL at room temperature. Our calculations reveal, Aβ42 peptide exhibit rapidly inter-converting conformations adopting extended chain as well as collapsed coil-like structures with a propensity to form few transient α-helices and β-sheets at intermediate times. We have correlated this higher flexibility of the peptide with formation of less stable salt-bridge in presence of IL in aqueous solution. It is found that water molecules around the polar regions are more structured imparting structural rigidity to the peptide backbone than around the hydrophobic domains. Thus identifying the effect of electrostatic interaction of IL on expulsion of water molecules from the polar domains on the peptide surface can shed light on preventing the aggregation process. We have also determined the most energetically stable peptide conformations from various accessible intermediate states using metadynamics simulations that are characterized by the rugged free energy surface having multiple energy basins.

Effect of Imidazolium Nitrate Ionic Liquids on Conformational Changes of Poly(N-vinylcaprolactam).

Detailed information about molecular interactions and conformational changes of polymeric components in the presence of ionic liquids (ILs) is essential for designing novel polymeric ionic liquid-based biomaterials. In biomaterials science and technology, thermoresponsive polymers (TRPs) are widely viewed as potential candidates for the fabrication of biorelated medical devices. Here, we synthesized thermoresponsive poly(N-vinyl-caprolactam) (PVCL) polymer and investigated the effects of imidazolium-based ILs (1-ethyl-3-methyl imidazolium nitrate and 1-butyl-3-methylimidazolium nitrate) with common anion and different cations on the phase transition behavior of PVCL aqueous solution. The impact of ILs on the phase transition behavior of PVCL was monitored by using UV-visible absorption spectra, steady-state fluorescence spectroscopy, thermal fluorescence spectroscopy, and temperature dependent dynamic light scattering. Results showed significant changes in the absorbance, molecular interactions, agglomeration, and coil to globule transition behaviors of PVCL in the presence of two ILs. PVCL aqueous solution showed significant conformational changes after the addition of ILs.

Anion Selection Criteria for Water-in-Salt Electrolytes

Water-in-salt electrolytes have enabled the development of novel high-voltage aqueous lithium-ion batteries due to their wide electrochemical stability window. Here, we explore why analogous sodium electrolytes have struggled to reach the same level of electrochemical stability and compare solution structure and electrochemical stability for eleven sodium salts, selected among the major classes of salts proposed for highly concentrated electrolytes.[1-3] We relate the water environment established for each anion to its position in the Hofmeister series, finding a strong correlation between the chaotropicity of the anion and the resulting electrochemical stability of the electrolyte. We discuss the importance of the solid-electrolyte interphase for stable battery performance, how it relates to the choice of anion, and further show that the search for suitable sodium salts is complicated by the fact that higher salt concentrations are needed than for their lithium equivalents.[4] Reaching such a high concentration of 25 to 30 mol/kg with one or a combination of multiple sodium salts that have the desired properties remains a major challenge. We conclude that alternative approaches such as mixed water/organic solvent or dual-cation electrolytes should be pursued to enable the development of high-voltage aqueous sodium-ion batteries. We demonstrate the potential of the mixed-solvent approach by showing that the water solubility of NaTFSI can be increased from 8 to 30 mol/kg in the presence of ionic liquids. Such a ternary electrolyte, based on highly chaotropic anions, enables stable cycling of a 2 V-class sodium-ion battery based on the NaTi2(PO4)3/Na2Mn[Fe(CN)6] electrode couple for 300 cycles at 1C with a Coulombic efficiency of >99.5%.[5]

Improved Oxygen Reduction Reaction (ORR) Kinetics Via Interfacial Engineering

Sluggish oxygen reduction reaction (ORR) kinetics, even on the best available catalyst (Pt), is one of the major challenges in widespread commercialization of polymer electrolyte membrane fuel cells (PEMFC).1 Significant advances have been made towards making highly active Pt catalysts through nanostructuring, alloying, size, and shape control to mitigate these kinetic losses.2 An additional strategy for ORR activity enhancement is though the targeted engineering of the electrochemical interface. For example, Ionic liquid (IL) interlayers improve the ORR kinetics on bulk and nanostructured catalysts for both Pt and alloyed-Pt materials.3 Along with the kinetic enhancement, ionic liquid interlayers also mitigate the sulfonate adsorption on Pt and improve the durability of Pt/C thin films.4,5 Despite remarkable improvement in performance at half-cell and MEA-level, the mechanism of this improvement is not completely understood. In this work, we combine single crystal voltammetry with microkinetic modeling to analyze the mechanism of ORR enhancement in presence of ionic liquids. With iterative feedback between single crystal voltammetry and microkinetic model output, we establish the importance of accounting for lateral interactions between adsorbed oxygenated species by using real data informed adsorption isotherms. With our experimentally validated model, we show that the mechanism of impact of ILs on ORR activity is through exclusion of water and reduction in electrochemical interface solvation, yielding lower spectator hydroxyl coverages and a reduced barrier for hydroxyl removal, resulting in higher surface site availability during the ORR. This improved understanding will help design Pt-interfaces to moderate the interaction of the interfacial water network with Pt active sites, providing another strategy for improving ORR kinetics.

Modifying Interface Solvation and Oxygen Reduction Electrocatalysis with Hydrophobic Species

Ionic liquid interlayers improve the oxygen reduction reaction (ORR) kinetics on bulk and nanostructured catalysts for both Pt and alloyed-Pt materials. Despite the demonstrated performance enhancement at the half-cell and membrane electrode assembly level, the mechanism of the improvement is not fully understood. In this work, we combine single-crystal experiments with microkinetic modeling to uncover the origin of the ORR kinetic improvement on Pt(111) in the presence of ionic liquids and hydrophobic cations. With the incorporation of a modified Frumkin isotherm, our model accurately simulates the disorder–order transition observed in hydroxyl and bisulfate adsorption on Pt(111) under acidic conditions. Voltametric analysis shows that ionic liquids impact solvation to break so-called scaling relations between the adsorption strength of OHad and Oad, but these effects have little impact on ORR activity. Instead, destabilized OHad reduces the overall hydroxyl (spectator) coverage, resulting in higher availability of active sites.

Influence of Ionic Liquids on the Aggregation and Pre-aggregation Phenomena of Asphaltenes in Model Solvent Mixtures by Molecular Dynamics Simulations and Quantum Mechanical Calculations

This work presents a systematic study of asphaltene pre-aggregation phenomena in the absence and in the presence of ionic liquids (ILs) from the family of 1-alkyl-3-methylimidazolium by molecular dynamics simulations. The effects of the alkyl chain length of the cation (studying ILs with alkyl chains between C4 and C10) and of the dimension of the anion (testing chloride and bromide) on the aggregation behavior of asphaltenes have been studied. To correlate the results obtained with the direct interaction between each additive and asphaltene, the latter was investigated both by the analysis of the radial distribution functions obtained by molecular dynamics simulations and quantum mechanical calculations. The DFT method was used to calculate the relative stability of the asphaltene-ionic liquid dimers and also the energy, shape, and spatial distribution of frontier orbitals. It was found that all the ionic liquids studied present a dispersing effect on asphaltene in model solvents, except for mixtures rich in toluene where, in most cases, the opposite effect is observed. This is accompanied by the interaction intensity as measured by radial distribution functions. The effects of the alkyl side chain length of the cation and of the anion radius are subtler, but it seems that the asphaltene dispersion effect increases with the length of the cation’s alkyl side chain and decreases with the radius of the anion; these effects are more clearly observed in the mixtures richer in n-heptane. These trends were corroborated by DFT calculations, which showed that the energetic stability of the asphaltene-additive dimer is as higher as the alkyl chain is longer and the anion is smaller. Pre-aggregation phenomena were also studied in mixtures containing CO2, which proved to be a precipitating agent as observed experimentally. The relative performances of the IL studied were not altered by the presence of CO2.

Study of M(hkl)| Ionic Liquid Interfaces in Well-Defined Surroundings

Ionic liquids have very interesting properties for their use in electrochemistry: they have a wide potential window of stability, high electrical conductivity and can replace water in processes in which water is not an appropriate solvent. Because of that, the number of studies has increased exponentially in recent years. When used in electrocatalytic applications, the structure of the interphase alters the electrocatalytic response of the electrode. For this reason, the characterization of the interphase, and especially the nature of the interaction of the ionic liquid with the metal surface becomes an essential element in the study of these reactions. In most cases, the interaction between the ions and the metal surface is specific, that is, a chemical interaction between the ionic liquid and the surface is established. Then, the interaction will depend on the nature of the ionic liquid and the electronic properties of the surface. This implies that this interaction is structure-sensitive. Practical surfaces are composed of several types of sites, which have different geometries and different interactions with the ionic liquid so that the observed responses are difficult to analyze. The best way to simplify the problem is the use of single crystal electrodes, which have a well-defined surface atomic structure, which allows establishing correlations between surface structure and observed behavior.One of the main disadvantages of using ionic liquids in electrochemistry is their high viscosity, which hinders the diffusion of the electroactive species towards the electrode surface and thus, lowering the reaction rates. This has triggered the study of low viscosity ionic liquids, which are usually those based on the imidazole cation ([Im+]) and/or the bis(trifluoromethyl)sulfonyl imide anion ([NTf2-]). It should be noted that the ionic liquid-electrode interphase is more complex than one in an aqueous medium. Ionic liquids have a higher electrostatic charge and interaction between the ions, which complicates the application of simple double-layer models. It is also important to highlight that, being organic compounds, they are prone to have impurities related to their synthesis processes, which can affect their physicochemical properties. In electrochemical systems in which ionic liquids are used, these liquids play the role of both solvent and electrolyte, which complicates the study of interactions, since the concentration of the ions is very high. To simplify the problem and to have a system with which to compare, ionic liquids can be dissolved in water. In this case, the concentration of the ions is reduced, facilitating their study. In addition, models are available to study and analyze their behavior. Thus, it is possible to analyze the effect of the concentration of the ionic liquid on its behavior and to extrapolate it to concentrations in which water is absent. In addition, due to the high hygroscopicity of ionic liquids, it is very difficult to completely eliminate water in practical applications. Furthermore, the presence of ionic liquids in aqueous solutions has been shown to catalyze some electrochemical reactions where small amounts of these have been shown to significantly increase the reaction rate. Thus, the aim of this work is to characterize the electrochemical behavior in water of the different ions that form the ionic liquids based in [Im]+ cation and ([NTf2]-) anion separately on platinum single crystal electrodes. To determine the role of each ion, different salts composed with at least one of the ions of interest ([Im]+ or ([NTf2]-)) will be used. The interactions of the ions and the electrode will be characterized using electrochemical and spectroelectrochemical techniques.

Ionic liquids in transdermal drug delivery system: Current applications and future perspectives

The transdermal drug delivery (TDD) shows considerable advantages over other administration pathways. However, conventional enhancing permeation methods face a series of challenges owing to barrier function provided by the skin, of which enhancing abilities either are so strong that it results in toxicity and irritation, or too weak to achieve desirable therapeutical effects. To address these issues, it is an urgent need to develop a novel method to overcome the limitations of current measures. Fortunately, in the preceding decades, ionic liquids (ILs) have been extensively studied and increasingly applied in pharmaceutical drug delivery due to their unique physicochemical and biological properties. What is more, tunability of structure resolves the challenges in processing active pharmaceutical ingredient (API) formulation, such as polymorphism and poor solubility of drugs. Thus, the presence of ILs provides an ample design space for the transdermal drug delivery system (TDDS). This review discusses the shortcomings of conventional enhancing permeation methods and introduces the application of ILs in transdermal delivery from three aspects: i) ILs are applied as enhancers to weaken the barrier function of the stratum corneum (SC). ii) As counterions, ILs are combined with API to modify the physicochemical properties of drugs. iii) ILs assist in the design of transdermal preparation for perfecting formulation. This review comprehensively introduces the major breakthroughs made in the applications of ILs, which can serve as guidance to provide novel ideas for formulation scientists who hit the bottleneck in the development of TDD.

Microscopic Softening Mechanisms of an Ionic Liquid Additive in an Electrically Conductive Carbon‐Silicone Composite

AbstractThe microstructural changes caused by the addition of the ionic liquid (IL) 1‐ethyl‐3‐methylimidazolium bis(trifluoromethylsulfonyl)imide to polydimethylsiloxane (PDMS) elastomer composites filled with carbon black (CB) are analyzed to explain the electrical, mechanical, rheological, and optical properties of IL‐containing precursors and composites. Swelling experiments and optical analysis indicate a limited solubility of the IL in the PDMS matrix that reduces the cross‐linking density of PDMS both globally and locally, which reduces the Young's moduli of the composites. A rheological analysis of the precursor mixture shows that the IL reduces the strength of carbon–carbon and carbon–PDMS interactions, thus lowering the filler–matrix coupling and increasing the elongation at break. Electromechanical testing reveals a combination of reversible and irreversible piezoresistive responses that is consistent with the presence of IL at microscopic carbon–carbon interfaces, where it enables re‐established electrical connections after stress release but reduces the absolute conductivity.

Influence of ionic liquid on rheological behaviors of candle soot and cellulose nanocrystal filled natural rubber nanocomposites

Carbonaceous soot nanoparticles are used as novel filler in combination with cellulose nanocrystal (CNC) to prepare natural rubber (NR) nanocomposites to which ionic liquid (IL) 1-allyl-3-methylimidazolium chloride is used to enhance the filler-rubber interaction. Nanocomposites of candle soot (CS) and CNC well dispersed in NR were prepared by latex mixing and mechanical mixing followed by vulcanization. The presence of IL causes a slight agglomeration of the fillers but it improves bound rubber content and crosslinking degree. Both the fillers and IL improve dynamic modulus and tensile stress while they lower loss tangent in the linear viscoelastic region, providing a perspective for manufacturing high–performance rubber materials using novel fillers and modifiers.

Effect of SiO2 nanoparticles + 1-dodecyl-3-methyl imidazolium chloride on the IFT and wettability alteration at the presence of asphaltenic-synthetic oil

Using nanoparticles (NPs) in different industries such as enhanced oil recovery processes increased during the past decade due to its significant effects on the wettability alteration and IFT reduction to some extent. On the other side, ionic liquids (ILs) are proposed a new class of solvents that introduce considerable advantages in different areas of sciences. In this way, a hybrid method based on the NPs and ILs is proposed in the current investigation. So, silicon dioxide (SiO2) as one of the most effective NPs on the wettability alteration and 1-dodecyl-3-methyl imidazolium chloride ([C12mim][Cl]) as a new class of surfactants are used to find their effects on the interfacial tension (IFT) reduction and wettability alteration at the presence of asphaltenic synthetic oil for the first time. In this way, the stability of SiO2-NPs at the presence of and absence of IL is examined which revealed stability of SiO2-NPs for more than one month at the presence of IL while fast precipitation was observed if no IL existed in the solution. After that, the effect of IL and SiO2-NPs on the IFT reduction and wettability alteration is investigated by changing the concentration of these chemicals between 0 and 2000 ppm and ranging the asphaltene content between 2 and 10%wt. The results revealed that for all of the examined concentrations of IL and asphaltene fraction, reduction in IFT is inevitable as the concentration increases. Besides, the results demonstrate that there is a threshold value for asphaltene content (6%wt) in which for the values below or higher than this threshold, the effect of IL on the IFT reduction reduces leading to the vanishing of a sharp reduction in IFT and determining a distinguished critical micelle concentration (CMC). According to findings, for asphaltenic synthetic oil (ASO) with 6%wt asphaltene content CMC value of 250 ppm is obvious while for the other ASO, no obvious and distinguished CMC values exist. Moreover, the results reveal that the IFT reduces to the value of 0.48 mN/m as the IL concentration increases to 2000 ppm while the asphaltene content is kept constant at 6%wt. Further IFT measurements demonstrate the negligible effect of SiO2-NPs on the IFT reduction while the concomitant existence of SiO2-NPs and IL with the concentration of 1000 ppm moves the wettability of the rock surface toward strongly water-wet with contact angle (CA) of 33.1°. The worth mentioning point is that the entire amount of reduction in the CA from 156.3° (initial condition) to 33.1° at the presence of hybrid solution is not completely due to the presence of SiO2-NPs and it is the cumulative effect of IL and SiO2-NPs presence. Finally, several core flooding experiments are performed using different chemical formulations which reveal that using a hybrid solution of SiO2-NPs + IL with a concentration of 1000 ppm for each chemical increases the tertiary oil recovery to 15.2%wt based on OOIP for the ASO/formation brine with asphaltene content of 10%wt.

Catalytic Effect of Ionic Liquid Induced H2-Release from Morpholine Borane Complex: An Efficient Hydrogen Storage Carrier

The demand for effective and secure chemical hydrogen storage systems impedes hydrogen’s usage as an alternative energy carrier. This work reports the use of morpholine borane (MB) as a novel, efficient, and widely viable chemical hydrogen storage material for mobile applications. Herein, for the first time, hydrogen generation from the thermolytic dehydrogenation of MB in the presence of ionic liquid (IL) media is reported. Initially, the COSMO-SAC model was utilized to determine the most appropriate solvent. [Bmim][HSO4] proved to be an excellent catalytic solvent media with maximum solubility in the morpholine borane complex. Thermal dehydrogenation experiments were conducted separately on solid-state and MB-IL systems at 60 and 80 °C in a vacuum-sealed experimental setup. After a prolonged heating period, the solid-state dehydrogenation of the MB complex released 0.62 equiv of hydrogen, whereas the dehydrogenation of the MB-IL system at 60 and 80 °C released 1.75 and 1.46 equiv of hydrogen in a shorter time. The residue products were characterized using 1H and 11B nuclear magnetic resonance (NMR). 1H NMR validated IL’s activity as a catalytic solvent without affecting its structural identity, whereas 11B NMR helped establish an intra- and intermolecular dehydrogenation mechanism connected with MB. As confirmed by the density functional theory-based transition state calculations, the intramolecular dehydrogenation pathway results in a dehydrocoupled product with minimal energy required for the dehydrogenation reaction.

Thermodynamic study of interfacial tension between oil and aqueous phases composed of ionic liquids and brine

The first fundamental step in determining the physicochemical properties of an equilibrium system is to determine the activity coefficient of electrolyte and non-electrolyte ions. Based on understanding the importance of activity coefficient in thermodynamic systems in this study, in order to predict interfacial tension between oil and aqueous phases composed of ionic liquids and brine, a modified thermodynamic equation based on concentration and coefficient of activity of ionic liquids is defined. For this study, the Extended UNIQUAC model is desired and its adjustable parameters are optimized with Genetic + PSO algorithm. The modified model has practical features such as investigating the effect of concentrations of salts in the water of oil fields formation on the interfacial tension of the system, investigating the effect of concentrations of various organic compounds such as ionic liquids on the interfacial tension of the system and investigating the interaction energy between organic and inorganic ions. In this study, the optimization of the modified thermodynamic equation to predict the interfacial tension of solutions containing [C8Py][Cl], [C18Py][Cl], [C12mim][Cl] and [C18mim][Cl] with the presence of brine and distilled water is investigated. Also, the effect of ionic strength of the solution in 32 equilibrium systems on interfacial tension is investigated. According to the optimization results of this study, the design of a computer program can be considered to predict the interfacial tension with the presence of ionic liquids and salts.

An Efficient and Green Synthesis of Tetrahydrobenzo[b]Pyran Derivatives Using [(EMIM)Ac] at Room Temperature

AbstractAn efficient, expedient, clean and environmental being synthesis of tetrahydrobenzo[b]pyran's twenty derivatives (4 a–t) has been reported via one‐pot three component condensation reaction of various benzaldehydes, dimedone and malononitrile in presence of ionic liquid [(EMIM)Ac] as a catalyst at ambient temperature in ethanol. Advantages of these reaction follow the principle of green chemistry, which are operational simplicity, shorter reaction time, and mild reaction conditions with high yield (78–98 %) products.