2-hydroxyethylammonium Formate Research Articles

The use of green protic ionic liquids in the crystallization of isoniazid: Evaluation of physicochemical and biological properties of drug

This study evaluated the synthesis of protic ionic liquids (PILs), 2-hydroxy ethylammonium formate (2-HEAF) and 2-hydroxy ethylammonium acetate (2-HEAA), and their applicability in the crystallization process of the active pharmaceutical ingredient isoniazid (INH) as anti-solvent. Isoniazid is an antibiotic used in the treatment of tuberculosis infections, being used as a first-line chemotherapeutic agent against Mycobacterium tuberculosis. Futhermore, this investigation was conducted in order to evaluate how these PILs can influence the habit, solubility, stability, and therapeutic efficiency of the obtained isoniazid crystals. The 2-HEAF and 2-HEAA PILs were easily formed in reactions between ethanolamine and carboxylic acids (formic or acetic acid), and they have no toxicity against Artemia salina. The PILs were able to crystallize isoniazid, influencing the crystal habit and size. The greatest variations in the hydrogen signals of the NH2 and NH groups of the amine and low variations in the chemical shifts of the hydrogens of the cation of the ethanolamine group from 2-HEAA and 2-HEAF indicate that PILs establish possibly weak interactions with INH. The obtained crystals were amorphous and showed higher solubility in water than standard INH. Moreover, these crystals showed therapeutic efficiency inantimycobacterial activity to inhibit the growth of Mycobacterium tuberculosis. The INH:2-HEAF only degraded 5.1 % (w/w), however, INH:2-HEAA degraded 32.8 % (w/w) after 60 days in an accelerated atmosphere. Then, the 2-HEAA and 2-HEAF were able to crystallize isoniazid, being a new application for these PILs. The used PILs also influenced the characteristics of isoniazid crystals.

Sulfonated poly(ether ether ketone)-Protic ionic Liquid-Based anhydrous Proton-Conducting composite polymer electrolyte membranes for High-Temperature fuel cell applications

A high-temperature polymer electrolyte membrane fuel cell (PEMFC) has enormous potential to produce clean energy with minimal environmental pollution along with high energy density and conversion efficiency. In the present work, anhydrous proton-conducting polymer electrolyte membranes for prospective high-temperature fuel cell application were successfully prepared using different protic ionic liquids (PILs) and sulfonated poly(ether ether ketone) (SPEEK). The protic ionic liquids (PILs), 2-hydroxyethylammonium formate, diethylmethyl ammonium triflate, 1-ethylimidazolium bis(trifluoromethylsulfonyl)imide, 1,2-dimethyl imidazolium bis(trifluoro methylsulfonyl)imide, and diethylmethylammonium methanesulfonate were selected based on their favorable physicochemical properties. The effect of the incorporation of the PIL on the structural, thermal, and electrical transport properties of the composite SPEEK polymer electrolyte membranes was studied. The prepared polymer electrolyte membranes (PEMs) were characterized using Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), X-ray diffractometry (XRD), and electrochemical impedance spectroscopy (EIS) techniques. FTIR results indicated an interaction between the PIL and the SPEEK, which resulted in homogeneous and flexible membranes. The DSC results confirmed good miscibility and elucidated plasticizing effect of the incorporated PIL on the SPEEK polymer matrix. All the PEMs showed good thermal stability and high-temperature anhydrous proton conductivity, achieving best proton conductivity, ≈8 × 10–3 S cm−1 at 120 °C and low activation energy ≈0.26 eV, making it suitable for prospective high-temperature PEMFC applications.

Unveiling the synergistic effect of ionic liquid and metal-organic framework on the efficiency of BiVO4: BiVO4-MIL-100(Fe) as a visible light-induced photocatalyst for Basic Red 46 degradation

Here, the effect of three different ionic liquids (IL) on the structural properties and photocatalytic activity of Bismuth Vanadate (BiVO4) was investigated. In this regard, BiVO4 hydrothermally synthesized in the presence of three different ionic liquids, including 2-hydroxyethyl ammonium formate, 1-Ethyl-3-methylimidazolium ethyl sulfate [Emim][EtSO4], and 1-Butyl-3-methylimidazolium methanesulfonate, [C4mim][MeSO3]. Additionally, the effect of calcination temperature was also studied by calcining hydrothermally synthesized BiVO4 at 600 °C, and all results were compared to a pure sample containing no IL. According to the characterization results, monoclinic scheelite-phase BiVO4 was only obtained in the presence of [Emim][EtSO4] and a higher temperature of 600 °C. To improve photocatalytic activity, the hybrid structure of IL-assisted BiVO4 with MIL-100 (Fe) was constructed by the in-situ growing of MIL-100(Fe) on the surface of BiVO4 and employed as a photocatalyst for the degradation of Basic Red 46. The IL-BiVO4-MIL-100(Fe) hybrid material exhibited higher photocatalytic activity than bare BiVO4, degrading more than 88% of Basic Red 46 in 120 min. To identify the photodegradation compounds and to determine the environmental fate of Basic Red 46, gas chromatography-mass spectrometry (GC–MS) was employed, and the possible degradation mechanism was discussed and proposed.

Thermal properties of phase change materials ionic liquid/fatty acids for thermal energy storage applications

Researchers have developed advanced energy storage techniques in response to the depletion of energy resources and the escalation of environmental problems caused by increasing population and technological advancements. One of the most promising methods to overcome such issues is the latent heat thermal energy storage (TES) method, which employs phase change materials (PCMs). TES using PCMs are an important category of novel materials that significantly contribute to the efficient use and conservation of solar energy and wasted heat. This work presents a new family of PCMs based on ionic liquid (IL) tris(2-hydroxyethylammonium) formate and fatty acids for the first time that operate in the temperature range of 50–150 °C and offer a safe and inexpensive capacity. Good chemical and thermal stability, low flammability, and low volatility along with the potential to tune chemical and phase properties provide an inherent “green” property for ILs that is well suited to PCMs. Using PCM3, tris(2-hydroxyethylammonium) formate/stearic acid, we demonstrate effective latent heat 246 J·g−1. The results of differential scanning calorimetry analysis show that the PCM2 tris(2-hydroxyethylammonium) formate/palmitic acid has a higher heat capacity 8.194 J·g−1·K−1 at the melting point than the other two PCMs due to its small alkyl chain. Thermal stability analyses show the maximum stability (98 %) for PCM3. Additionally, based on the structure of these PCMs, this study explores the molecular basis for the high thermal energy storage capacity of these materials and highlights the significance of hydrogen bonds in PCM performance. Using simple, cost-effective materials, this method gets around the complexity and expense of composite PCMs. We present design recommendations for implementing our approach in the management of thermal energy storage applications.

Exploring solvation behaviour of biocompatible ionic liquid 2-hydroxyethylammonium formate + polyethylene glycols mixtures: Role of oxyethylene and hydroxyl units of PEGs

The favourable modification of the physicochemical properties of the ionic liquid with green co-solvent and their molecular level characterization with spectroscopic techniques is the area of current research. Further, the co-solvent modified ionic liquid mixtures furnishes interesting properties which render the utility of these solvents in several important applications. In the current work, the effects of addition of two polyethylene glycols (PEGs) with average molecular weights of 200, and 600 on solvent properties of IL 2-hydroxyethyl ammonium formate (HEF) has been explored with the help of solvatochromic absorbance probes. The physicochemical characteristics of the ionic liquid mixtures are altered in an unexpectedly positive way when PEGs are added to IL HEF. The absorbance behaviour of the solvatochromic probes Reichardt dye 33 shows interestingly positive non-ideal behaviour, which may be attributed to the high dipolarity/polarizability (π*) and hydrogen bond donor ability (HBD) (α) of the HEF + PEG mixtures. Further, the Kamlet-Taft parameters, including hydrogen bond acceptor ability (HBA) (β), and hydrogen bond donor ability (HBD) (α), and dipolarity/polarizability (π*) of the HEF + PEG binary mixtures display nonideality, which may be because of the strong Hydrogen bond networking of HEF-PEG molecules along with solute-HEF/PEG interaction present in the mixtures. Moreover, the preferential solvation approach has been invoked to explore the solute–solvent/solvent–solvent interactions present in the HEF + PEGs binary mixtures. The Redlich–Kister (CNIBS/R–K) theoretical model predicts the experimental results obtained by solvatochromic probe studies in satisfactory manner. The results of the DFT and FTIR study also predict the possibility of the H-bonding interactions in HEF + PEGs mixtures.

2-hydroxyethylammoniumsulfate ionic liquid performance as simultaneous fuel and sulfating agent in tablet-like manganese and iron incorporated titania synthesis: Biodiesel production from waste oil

The efficient tablet-like manganese and iron incorporated titania catalyst was synthesized in the presence of 2-hydroxyethylammonium sulfate (ILS) as both fuel and sulfating agent via microwave for biodiesel production. Catalyst characterizations were conducted by XRD, FESEM, EDX, BET-BJH, and TPD-NH3 analyses. The catalyst was also synthesized via other fuels including urea, 2-hydroxyethylammonium acetate (ILA), and 2-hydroxyethylammonium formate (ILF). The nature of fuels affected the catalyst’s physicochemical properties and performance. Urea created a large portion of wide pores in the catalyst. ILS led to the creation of a highly acidic catalyst with an acid density of 0.804 mmol/m2. Oleic acid conversion for catalysts synthesized by urea, ILA, ILF, and ILS in the condition of 110 °C, 1.5 h, 9 wt% catalyst, alcohol to oil mole ratio of 20 was 63.5, 39.36, 48.56, and 93.11 %. MnFeTi(ILS) showed a good capability for producing biodiesel from sunflower (92.12 %) and waste oil (91.43 %). The catalyst was reused 5 times, and only a 6 % conversion loss was detected.

DFT and ab initio molecular dynamics simulation study of the infrared spectrum of the protic ionic liquid 2-hydroxyethylammonium formate.

Protic ionic liquids (PILs) typically show a complex band shape in their infrared (IR) spectra in the high-frequency range due to the hydrogen stretching vibrations of functional groups forming rather strong hydrogen bonds (H-bonds). In the low-frequency range, the intermolecular stretching mode of the H-bond leaves a mark in the far-IR spectrum of PILs. In this study, the IR spectrum of the PIL 2-hydroxyethylammonium formate, [HOCH2CH2NH3][HCOO], is investigated in order to identify the different modes that contribute to the high-frequency band shape, i.e. the cation ν(NH), ν(OH), and ν(CH) modes, and the anion ν(CH) mode, as well as the intermolecular mode of the strongest H-bond in the far-IR spectrum. The assignment is validated by quantum chemistry calculations of clusters at the density functional theory (DFT) level for four ionic pairs and by ab initio molecular dynamics (AIMD) simulations of ten ionic pairs. There is good agreement between the vibrational frequencies obtained from DFT and AIMD simulations for both the high- and low-frequency ranges. Based on the calculations, the strong H-bond interaction between the cation -NH3 group and [HCOO]- gives a broad band envelope associated with the ν(NH) mode in the high-frequency range of the IR spectrum on which there are narrower peaks corresponding to the ν(OH) and ν(CH) modes. In the far-IR (FIR) spectrum, the anions' rattling motion gives a broad feature with a maximum at 160 cm-1, while the H-bond's intermolecular NH⋯O stretching mode appears as a peak at 255 cm-1.

Selective Partition of Lipopeptides from Fermentation Broth: A Green and Sustainable Approach.

Lipopeptide (LP) biosurfactants from microbes have the potential to gradually replace chemical synthetic surfactants and fit the contemporary green and sustainable industrial production concept. However, their active participation is comparatively low in the global market pertaining to their low yield in microbial broth and costly downstream processes arising due to tedious isolation and purification methods. Herein, an efficient extraction method is developed that utilizes an aqueous biphasic system (ABS) comprising ionic liquids and polypropylene glycol 400 (PPG) to selectively extract a mixture of cyclic lipopeptides, namely, surfactin and fengycin from the culture broth of Bacillus amyloliquefaciens 5NPA-1, isolated from the halophyte Salicornia brachiata Roxb. Out of four different ABSs, the ABS composed of 2-hydroxyethyl ammonium formate and PPG displayed a maximum extraction efficiency of 82.30%. PPG-rich phase containing lipopeptides exhibited excellent antimicrobial and mosquito larvicidal properties with no toxic effect on plants. The developed method is simple, novel and accelerates the application of cyclic lipopeptides produced by the microbial source.

Solubilities of caffeic acid and tyrosol in two protic ionic liquids and one deep eutectic solvent

The present work provides solubility measurements for two phenolic compounds, caffeic acid and tyrosol, in two protic ionic liquids, 2-hydroxyethylammonium formate (2HEAF) and 2-hydroxyethylammonium acetate (2HEAA), and in the Deep Eutectic Solvent (DES) choline chloride-urea (ChCl:urea (1:2)). Solubility measurements of tyrosol were also performed in ethanol and water. All measurements were conducted under atmospheric pressure and in the temperature range of 293.15–313.15 K. Moreover, densities of pure 2HEAF, 2HEAA and ChCl:urea (1:2) and the viscosity of ChCl:urea (1:2), were measured. ChCl:urea (1:2) showed the highest solvation capacity among all the solvents studied for both compounds, while tyrosol was found to be more soluble than caffeic acid in all solvents. In order to better understand the solubilization process, the van't Hoff equation was applied for calculating the apparent Gibbs energy, enthalpy and entropy of solution. Finally, correlation of the solubility data was achieved with UNIQUAC and NRTL activity coefficient models.

Poly(Vinyl Alcohol)/ N-Methylene Phosphonic Chitosan/ 2-Hydroxyethylammonium Formate (PVA/NMPC/2-HEAF) Membrane for Fuel Cell Application

The cost of conventional membrane, Nafion® used in the current proton exchange membrane fuel cell (PEMFC) is high. Thus different alternatives are being proposed as an option of Nafion® membrane in PEMFC application. In this study, poly(vinyl alcohol)/ N-methylene phosphonic chitosan/ 2-hydroxyethylammonium formate (PVA/NMPC/2-HEAF) proton exchange membrane was prepared using the solution casting technique. The effects of 2-HEAF concentrations (0 – 20 wt.%) on crosslinked and non-crosslinked PVA/NMPC/2-HEAF membrane were studied. The characterizations of PVA/NMPC/2-HEAF membrane were done by Fourier transformation infrared spectroscopy (ATR-FTIR), water uptake test, ion exchange capacity (IEC) analysis and electrochemical impedance spectroscopy (EIS). The crosslinkages (-O-CH2-O-) formed using formaldehyde crosslinking agent were confirmed through the formation of new peak by –CH2- stretching at around 2863 cm-1 and the increased intensity of C-O stretching absorption. Crosslinked PVA/NMPC/5 wt.% 2-HEAF membrane showed the highest percentage of water uptake and IEC value. The EIS result agrees with the water uptake and IEC analysis where crosslinked PVA/NMPC/5 wt.% 2-HEAF showed the highest ionic conductivity of 5.44 × 10-5 S cm-1. This is due to the plasticization effect of 2-HEAF that softened the polymer chains and which it also provided more charge carriers to increase the ion mobility in the membrane.

Green and Fast Synthesis of 2-Arylidene-indan-1,3-diones Using a Task-Specific Ionic Liquid.

A novel method for condensation reaction of indan-1,3-dione with various aldehydes which are efficiently catalyzed by a task-specific ionic liquid, 2-hydroxyethylammonium formate, to provide the corresponding 2-arylidenindane-1,3-diones has been developed. This green, low-cost, high-yield, and fast reaction takes place at room temperature without the use of any solvent and catalyst. A plausible reaction mechanism that involves ionic liquid-assisted activation is also discussed. This work is the first report of ionic liquids as a reaction medium and catalyst for the synthesis of 2-arylidenindane-1,3-diones.

Investigating the effect of electrolyte types with various ionic liquids on the electrochromic performance of PEDOT:PSS based LbL multilayers

The objective of the study is to investigate the electrochromic performances of layer-by-layer (LbL) multilayered thin film electrode prepared from linear polyethylene imine (LPEI) and poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) on PET-ITO substrate in the presence of different types of electrolytes. For this purpose, the electrochromic behaviors of (LPEI/PEDOT:PSS)10 is performed in LiClO4/propylene carbonate (PC) and two different ionic liquids (IL) namely N-methylimidazolium tetrafluoroborate (Melm-BF4) and 2-hydroxy ethyl ammonium formate (2-HEAF), as a function of IL content and scanning rate. The optical contrast value of (LPEI/PEDOT:PSS)10 film is determined as 58.4% in the existence of 10 wt% of 2-HEAF as the electrolyte. The coloration efficiency of this film is determined as 606.7 cm2/C, which this value was greater approximately four times than 1 M LiClO4/PC. According to the obtained results, 2-HEAF has been evaluated as a suitable electrolyte alternative for (LPEI/PEDOT:PSS)10 film due to its better optical contrast and coloration efficiency compared to other electrolytes.

Application of protic ionic liquids in the microwave-assisted extraction of phycobiliproteins from Arthrospira platensis with antioxidant activity

Phycobiliproteins are potential molecules for use in various applications. Although phycobiliproteins extraction classical methods are reproducible and show good yields, they are generally time-consuming and require the use of high energy consumption and/or large volumes of solvent. Therefore, it is necessary the development of new eco-friendlier process by extraction techniques, permitting the transfer of the results obtained in laboratory scale for industrial. Then, microwave-assisted extraction using protic ionic liquid as solvent was proposed and optimized to extract phycobiliproteins from Arthrospira platensis in an efficient manner. The protic ionic liquids (PILs): 2-hydroxyethylammonium acetate (2-HEAA), 2-hydroxyethylammonium formate (2-HEAF), their equimolar mixture (2-HEAA + 2-HEAF), and the commercial ionic liquid 1-butyl-3-methylimidazolium chloride [Bmim]Cl were used as solvents, and sodium phosphate buffer as a control and the conditions of extraction were evaluated. The irradiation power was the most significant variable for the extraction process, and it showed a negative effect. The process conducted at 62 W and pH 7.0, using 2-HEAA + 2-HEAF and a solvent: biomass ratio of 10 mL∙g−1, showed the highest phycobiliproteins concentrations. The purity obtained for phycocyanin, allophycocyanin and phycoerythrin were 1.22, 1.03, and 0.71, respectively. The mixture of the PILs (2-HEAA + 2-HEAF) can be reused for three cycles for extraction of allophycocyanin. The extraction of phycobiliproteins using microwave and ionic liquids was efficient and the degree of purity and antioxidant activity achieved allows the application of these pigments in food and cosmetics.

Neoteric Solvent Systems as Sustainable Media for Dissolution and Film Preparation of Poly-[(R)-3-hydroxybutyrate

Polyhydroxyalkanoates (PHAs) have a wide range of applicability due to their biodegradable and biocompatible characteristics. This makes them suitable for commercialization as an alternative to petroleum-based synthetic plastics. Solvents such as chloroform are reported to solubilize polyhydroxyalkanoates. With chloroform being hazardous for both health and the environment, this work attempts to replace this chlorinated solvent with green solvents like ionic liquids. In this study, poly-[(R)-3-hydroxybutyrate] (PHB) was extracted from Halomonas hydrothermalis, and its solubility, stability, and film-forming ability were investigated in the presence of ammonium-based ionic liquids (ILs). Among the studied ILs, maximum solubility (3% w/v at 70 °C) along with chemical and structural stability of the polymer was observed in diethanol ammonium acetate (DA), while the lowest dissolution (0.4% w/v) was exhibited in 2-hydroxyethylammonium formate (HF). The molecular docking studies have established a critical role of the anions of the ILs in the dissolution process. Further, PHB dissolved in DA formed a film in the presence of gelatin (G). The recovered ILs were found to be soil compatible, and due to their high nitrogen content, they can be used as a fortifier for nitrogen-deficient seaweed-based liquid plant biostimulants making them suitable soil nutrients for agriculture applications.

Viscosities of pure protic ionic liquids and their binary and ternary mixtures with water and ethanol

The knowledge of the viscosity of ionic liquids is crucial for the design and development of industrial processes that involve these fluids, as well as for the theoretical study of this property. In this study, viscosities of four protic ionic liquids (PILs) consisting of ethanolamine as cation and formate, acetate, butyrate and hexanoate as anions, have been measured at the temperature range from 293.15 to 393.15 K, at atmospheric pressure. Viscosities of binary and ternary mixtures of these ionic liquids with water and ethanol at 293.15, 298.15 and 303.15 K have been also measured. PILs were found to be highly viscous fluids, except for 2-hydroxyethylammonium formate, and their viscosity is affected to a great extent by the presence of water and/or ethanol. The temperature dependency of the viscosity for pure ionic liquids is analyzed by means of the Vogel-Tammann-Fulcher equation, while for ionic liquid mixtures a modified Grunberg-Nissan equation is developed in this work. Satisfactory agreement between the experimental data and the model was obtained in all cases. Finally, the glass transition temperature of the PILs was measured.

Ionic Dynamics of Hydroxylammonium Ionic Liquids: A Classical Molecular Dynamics Simulation Study.

We report the structure and dynamics of four ionic liquids (ILs), 2-hydroxyethylammonium formate, bis-(2-hydroxyethyl) ammonium formate, tris-(2-hydroxyethyl) ammonium formate (THEF), and 2-hydroxyethylammonium lactate, employing classical molecular dynamics simulations. The dynamics of ILs are represented by studying mean squared displacements (MSDs), velocity autocorrelation functions (VACFs), and current auto-correlation functions (CACFs). Diffusion coefficients calculated from the VACFs are higher than those obtained from MSDs. The diffusion coefficients calculated from both the methods (MSDs and VACFs) were averaged to calculate the uncorrelated ionic conductivities (ICs). ICs from these two methods agree with the experimental trend. The correlated and uncorrelated ICs were calculated by four methods and compared with experiments. The difference between CACF and center of mass VACF accounts for the correlated motion present in the ILs. The addition of hydroxyalkyl chains on cations causes the dynamics to become slow. The number of hydroxyl groups present on the cations affects the dynamics of ILs studied. A tris-(2-hydroxyethyl) ammonium cation has lower diffusion than any other ions because of the higher molecular weight and number of hydroxyl groups on the cation. We explored the dynamics of hydrogen bonding by calculating the continuous and intermittent hydrogen bond autocorrelation functions. Radial distribution functions between the functional groups of cations and anions reveal the structural arrangement in ILs. The coordination numbers decrease with the increase in the bulkiness of cations due to steric hindrance. Spatial distribution functions of anions around cations show that anions occupy the space around the ammonium hydrogen atoms of the cations. Ion-pair and ion-cage dynamics show that THEF has slower dynamics than the other three ILs and is consistent with MSDs. The inverse of ion-pair and ion-cage lifetimes shows a linear relationship with ICs.

One step selective partition of ε-polylysine present in broth cultures in ionic liquid-based aqueous biphasic systems

ABSTRACT Four different ionic liquids were synthesized, characterized and used with polypropylene glycol for the formation of aqueous biphasic systems and were used to selectively separate ε-PL from culture broth. It was observed that the partition of ε-PL to the IL-rich phase was achieved, and with pure ε-PL, the extraction efficiency was found to be 99.92% while with culture broth, it was 93.42% for the ABS formed with 2-hydroxyethylammonium formate. Preservation of the chemical and structural stability of ε-PL in the ABSs indicated the potential of such systems as remarkable platform for the selective separation of ε-PL from the culture broth.

Uncovering the potentialities of protic ionic liquids based on alkanolammonium and carboxylate ions and their aqueous solutions as non-derivatizing solvents of Kraft lignin

The present study scrutinized in depth the ability of alkanolammonium-based Protic Ionic Liquids (PILs) with carboxylate anions to dissolve Kraft lignin at 323.15 K. A focus was put on understanding the role of both PIL ions and water on the dissolution process. The results demonstrated that the anion plays a more important role in lignin dissolution than the cation. Furthermore, lignin dissolution was favored by increasing the alkyl chain of the carboxylate anion, while a smaller cation with lower number of hydroxyalkyl groups performed better. Among the studied solvents, the 2-hydroxyethylammonium hexanoate (HEAH) displayed the highest lignin solubility (37 wt%). In general, the addition of water had a negative influence on lignin solubility with the tested PILs. A sharp decrease in lignin solubility curves of 2-hydroxyethylammonium formate (HEAF) and acetate (HEAA) was observed, while a more softly effect was observed for 2-hydroxyethylammonium propionate (HEAP) and HEAH with the addition of water. However, a distinct behavior was observed for 2-hydroxyethylammonium octanoate (HEAO) that acted as hydrotrope enhancing lignin solubility in aqueous solutions to a maximum value at 40 wt% water content. Furthermore, by increasing the temperature, the lignin solubility was favored due to endothermic behavior of lignin dissolution process.The dissolution of Kraft lignin was also performed at 393.15 K to unravel any lignin modification unleashed by PILs. GPC, FTIR-ATR and 2D NMR were employed for lignin characterization and the changes observed between native lignin and recovered lignin samples were negligible demonstrating the non-derivatizing character of the PILs. Moreover, the recycle of 2-hydroxyethylammonium propionate (HEAP) was successfully demonstrated for at least 3 cycles. In this way, PILs are herein revealed as promising solvents to apply in lignin valorization towards more efficient and eco-friendly processes.

Viscosities of 2-hydroxy ethylammonium formate ionic liquid from 0.1 MPa to 40 MPa: Measurement and modelling

This work extended the measurements of dynamic viscosities of 2-hydroxy ethylammonium formate (2-HEAF) ionic liquid to high-pressure. The dynamic viscosities were measured in (298.15–328.15) K range and pressures from (0.1 to 40) MPa with the uncertainties within ±(0.85–5.3) mPa s. The experimental data were correlated/predicted using a two-parameter empirical equation as well as semi-theoretical model based on the rough-hard-sphere theory (RHS) with the average absolute relative deviation of 1.14% and 2.18%, respectively. The RHS model used two molecular parameters as well as the liquid densities, for which the values were estimated from perturbed hard-sphere equation of state. The experimental results have also been compared with those coming from the previously reported molecular dynamics results. Additionally, molecular dynamics results allowed a nanoscopic level analysis of the main features controlling viscosity in terms of hydrogen bonding properties and changes with temperature and pressure.

Thermally induced characterization and modeling of physicochemical, acoustic, rheological, and thermodynamic properties of novel blends of (HEF + AEP) and (HEF + AMP) for CO2/H2S absorption.

CO2 and H2S removal from flue gases is indispensable to be done for protection of environment with respect to global warming as well as clean air. Chemical absorption is one of the most developed and capable techniques for the removal of these sour gases. Among the many solvents, ionic liquids (ILs) are more capable due to their desirable green solvent properties. However, ILs being usually costlier, the blends of ILs and amines are more suggestive for absorption. In the present work, various essential characterization properties such as density, viscosity, sound velocity, and refractive index of two ionic liquid-amine blend systems viz. (1) 2-Hydroxy ethyl ammonium formate (HEF) + 1-(2-aminoethyl) piperazine (AEP) and (2) 2-Hydroxy ethyl ammonium formate (HEF) + 2-Amino-2-methyl-1-propanol (AMP) are reported. The temperature range for which all the measurements were conducted is 298.15 to 333.15 K. For both systems of (HEF + AEP) and (HEF + AMP), HEF mass fractions were varied from 0.2 to 0.8.The density and viscosity results were correlated as a function of temperature and concentration of ionic liquid and amine with Redlich-Kister and Grunberg-Nissan models, respectively. Moreover, feed forward neural network model (ANN) is explored for correlating experimentally determined sound velocity and refractive index data. The measured properties are further analyzed to estimate various thermodynamic as well as transport properties such as diffusivity of CO2/H2S in the (HEF + AEP) and (HEF + AMP), thermal expansion coefficients, and isentropic compressibility, ΔG0, ΔS0, ΔH0, using the available models in the literature.