Nitrate Ionic Liquid Research Articles

Understanding the coordination behavior of quaternary ammonium and phosphonium nitrate ionic liquids under gamma irradiation: A combined spectroscopic investigation

In the process of spent nuclear fuel reprocessing, it is very essential to investigate the radiation stability of the extracting phase.From the ionic liquid (IL) family, quaternary ammonium or phosphonium based ILs: methyltrioctylammonium nitrate ([N1888][NO3]) or trihexyl(tetradecyl)phosphonium nitrate ([P66614][NO3]) have many commendable features while being used as the solvent for the extraction and separation of the target metal ions from nuclear waste solution. In this context, a comparative investigation on the irradiation effect on the stability of [N1888][NO3] and [P66614][NO3] and their coordination ability towards acid and metal ion was furnished systematically. A marginal change in the extraction ability was acquired upon irradiation. The spectroscopictechniques such as UV–Visible, ATR-FTIR and fluorescence spectroscopy were employed to deduce the intrinsic role of the applied dose. The peak at ∼ 260 nm in UV–Visible spectra is broadened and red shifted upon irradiation for both ILs with substantial shift in [P66614][NO3]. FTIR spectra suggests the appearance of new peaks at 752 cm−1 upon radiation exposure for both ILs indicating the formation of degraded products of NO3– ion (bending vibration of NO2. radical) and - CH2 group (cleavage of - H. radical). A remarkable difference in the peak intensity and shape for [P66614][NO3] as compared to [N1888][NO3] confirms the radiation tolerance level of two ILs. For both irradiated and unirradiated ILs, the presence of water coordination was confirmed due to the peak at (bending mode of H2O), which later showed blue shift upon metal (or acid) loading.Luminescence patterns of Eu(III) in the irradiated ILs realizes an adequate quenching of Eu(III) emission in [P66614][NO3] in comparison to [N1888][NO3] which was less affected by the radiation. In all the spectroscopic evidences specify the vital role of NO3– anion in altering the radiation stability of ILs.

Comprehensive investigation of two environmentally-friendly imidazolium nitrate ionic liquids: from calorimetry to thermal risk evaluation

Comprehensive investigation of two environmentally-friendly imidazolium nitrate ionic liquids: from calorimetry to thermal risk evaluation

Feed phase salting agent prevails the absence of organic phase Ligand: A sustainable extraction process for Eu(III)/Am(III) in an undiluted phosphonium ionic liquid

• Europium(III)/Americium(III) extraction by undiluted Cyphos nitrate ionic liquid. • Appreciable extraction factors with the use of low cost and readily available salting agent in the feed phase. • Avoidance of any extra ligand in the ionic liquid phase for the extraction process. • Straightforward extraction mechanism rendering the complexation of M(III) in the ionic liquid phase. • Quantitative stripping within 2–3 stages using Millipore water. Long chain quarternary alkyl phosphonium based ionic liquids have several fascinating merits over conventional imidazolium based ionic liquids. In this context, trihexyl(tetradecyl)phosphonium nitrate ([P 66614 ][NO 3 ]) ionic liquid (commonly known as cyphos nitrate) was chosen as the extractant in its undiluted status for the extraction and separation of trivalent Ln(III)/An(III) from the nitric acid phase. Experimental parameters such as the concentration of initial nitric acid, initial nitrate ion in the feed phase, initial feed metal concentration, equilibration time, etc. were varied precisely to furnish the extraction process. The major highlights in the study is the fascinating salting effect of the feed phase NO 3 – ion in the efficient extraction of Eu(III)/Am(III). This methodology avoids the use of additional extractant in the ionic liquid phase for extracting the metal ion leading to an economical process. The use of [P 66614 ][NO 3 ] avoids the loss of any ionic liquid component to the aqueous phase during the extraction. The proposed ionic liquid was found to be radiation stable which enhances its reliability as solvent for the separation of Ln(III)/An(III) in the context of spent nuclear fuel reprocessing. The present ionic liquid was found to be superior in metal loading in comparison to other ionic liquids with similar type of structure. Another underscore of the present study is the use of only Millipore water as the stripping agent without adding any aqueous phase complexing agent which certainly offer economic and environmental benefit.

Phosphorylated chitosan/poly(vinyl alcohol) based proton exchange membranes modified with propylammonium nitrate ionic liquid and silica filler for fuel cell applications

In our previous work, phosphorylated chitosan was modified through polymer blending with poly(vinyl alcohol) (PVA) polymer to produce N-methylene phosphonic chitosan/poly(vinyl alcohol) (NMPC/PVA) composite membranes. The aim of this work is to further investigate the effects of a propylammonium nitrate (PAN) ionic liquid and/or silicon dioxide (SiO2) filler on the morphology and physical properties of NMPC/PVA composite membranes. The temperature-dependent ionic conductivity of the composite membranes with various ionic liquid and filler compositions was studied by varying the loading of PAN ionic liquid and SiO2-PAN filler in the range of 5–20 wt%. As the loading of PAN ionic liquid increased in the NMPC/PVA membrane matrix, the ionic conductivity value also increased with the highest value of 0.53 × 10−3 S cm−1 at 25 °C and increased to 1.54 × 10−3 S cm−1 at 100 °C with 20 wt% PAN. The NMPC/PVA-PAN (20 wt%) composite membrane also exhibited the highest water uptake and ion exchange capacity, with values of 60.5% and 0.60 mequiv g−1, respectively. In addition, in the single-cell performance test, the NMPC/PVA-PAN (20 wt%) composite membrane displayed a maximum power density, which was increased by approximately 14% compared to the NMPC/PVA composite membrane with 5 wt% SiO2-PAN. This work demonstrated that modified NMPC/PVA composite membranes with ionic liquid PAN and/or SiO2 filler showed enhanced performance compared with unmodified NMPC/PVA composite membranes for proton exchange membrane fuel cells.

Metabolomic analysis of Scenedesmus obliquus reveals new insights into the phytotoxicity of imidazolium nitrate ionic liquids

Due to the persistence of ionic liquids (ILs) in aquatic environments, it is necessary to reveal their ecological risk to aquatic organisms. Herein, the biotoxicity of two alkyl-methylimidazolium nitrate ILs ([C10mim]NO3 and [C12mim]NO3) against Scenedesmus obliquus were studied. Results showed that the growth inhibition of S. obliquus increased with increasing concentrations of ILs, maximum values of 94.61% at 4 mg/L of [C10mim]NO3 and 97.34% at 0.8 mg/L of [C12min]NO3 were observed. The fluorescence parameters of photosystem II, such as light quantum yield and electron transfer rate, showed a negative relationship with the exposure dose. [C12mim]NO3 had a more significant effect than [C10mim]NO3. Moreover, the redox homeostasis of algae was disrupted; the accumulation of reactive oxygen species, leading to obvious inhibition of superoxide dismutase and catalase activities was observed. A metabolomic analysis indicated that the contents of most metabolites were reduced significantly, and fructose and galactose decreased significantly by 42.3% and 88.6%, respectively, in the [C10mim]NO3 treatment compared to those in the control. The inhibition of amino acid biosynthesis and glyoxylate and dicarboxylate metabolism explained the more serious biotoxicity of [C12mim]NO3 than that of [C10mim]NO3. This study facilitates a better understanding of the environmental safety and ecological risks of ILs.

Multistep phase transition in 1-decyl-3-methylimidazolium nitrate ionic liquid

Cooling-rate dependent multistep phase transition of 1-decyl-3-methylimidazolium nitrate ([C10mim][NO3]) was investigated at low temperature (LT) by conducting simultaneous small- and wide-angle X-ray scattering and differential scanning calorimetry (DSC) measurements. Above 9 ℃/min (nonequilibrium), crystallization of [C10mim][NO3] was suppressed upon cooling, whereas cold crystallization appeared upon heating. At the cooling rate region between 5 ℃/min and 8 ℃/min (quasiequlibrium), a multistep phase transition was identified on the DSC thermal traces. The Bragg reflection at the lowest scattering angle was located at a different position from that of the prepeak in the liquid state. A long periodic layered structure was formed at LT.

Thermal and Catalytic Decomposition of 2-Hydroxyethylhydrazine and 2-Hydroxyethylhydrazinium Nitrate Ionic Liquid

To develop chemical kinetics models for the combustion of ionic liquid-based monopropellants, identification of the elementary steps in the thermal and catalytic decomposition of components such as 2-hydroxyethylhydrazinium nitrate (HEHN) is needed but is currently not well understood. The first decomposition step in protic ionic liquids such as HEHN is typically the proton transfer from the cation to the anion, resulting in the formation of 2-hydroxyethylhydrazine (HEH) and HNO3. In the first part of this investigation, the high-temperature thermal decomposition of HEH is probed with flash pyrolysis (<1400 K) and vacuum ultraviolet (10.45 eV) photoionization time-of-flight mass spectrometry (VUV-PI-TOFMS). Next, the investigation into the thermal and catalytic decomposition of HEHN includes two mass spectrometric techniques: (1) tunable VUV-PI-TOFMS (7.4-15 eV) and (2) ambient ionization mass spectrometry utilizing both plasma and laser ionization techniques whereby HEHN is introduced onto a heated inert or iridium catalytic surface and the products are probed. The products can be identified by their masses, their ionization energies, and their collision-induced fragmentation patterns. Formation of product species indicates that catalytic surface recombination is an important reaction process in the decomposition mechanism of HEHN. The products and their possible elementary reaction mechanisms are discussed.

Influence of Mixed Imide Composition and Thermal Annealing on Ionic Liquid Uptake and Conductivity of Polyimide-Poly(ethylene glycol) Segmented Block Copolymer Membranes.

Understanding the impact of different bridging groups in the two-step polymerization of poly(ethylene glycol) (PEG)-incorporated polyimide (PI) materials is significant. It is known that the proton exchange membranes (PEMs) used in industry today can experience performance degradation under rising temperature conditions. Many efforts have been devoted to overcoming this problem by improving the physical and mechanical properties that extend the hygrothermal life of a PEM. This work examines the effect of oxygenated and fluorinated bridging anhydrides in the production of PI-PEG PEMs. It is shown that the dianhydride identity and the amount incorporated in the synthesis influences the properties of the segmented block copolymer (SBC) membranes, such as increased ionic liquid uptake (ILU), enhanced conductivity and higher Young’s modulus favoring stiffness comparable to Nafion 115, an industrial standard. Investigations on the ionic conductivity of PI-PEG membranes were carried out to determine how thermal annealing would affect the material’s performance as an ion-exchange membrane. By applying a thermal annealing process at 60 °C for one hour, the conductivities of synthesized segmented block copolymer membranes values were increased. The effect of thermal annealing on the mechanical properties was also shown for the undoped SBC via measuring the change in the Young’s modulus. These higher ILU abilities and mechanical behavior changes are thought to arise from the interaction between PEG molecules and ethylammonium nitrate (EAN) ionic liquid (IL). In addition, higher interconnected routes provide a better ion-transfer environment within the membrane. It was found that the conductivity was increased by a factor of ten for undoped and a factor of two to seven for IL-doped membranes after thermal annealing.

Influence of Small Quantities of Water on the Physical Properties of Alkylammonium Nitrate Ionic Liquids.

This paper presents a comprehensive study of two alkylammonium nitrate ionic liquids. As part of this family of materials, mainly ethylammonium nitrate (EAN) and also propylammonium nitrate (PAN) have attracted a great deal of attention during the last decades due to their potential applications in many fields. Although there have been numerous publications focused on the measurement of their physical properties, a great dispersion can be observed in the results obtained for the same magnitude. One of the critical points to be taken into account in their physical characterization is their water content. Thus, the main objective of this work was to determine the degree of influence of the presence of small quantities of water in EAN and PAN on the measurement of density, viscosity, electrical conductivity, refractive index and surface tension. For this purpose, the first three properties were determined in samples of EAN and PAN with water contents below 30,000 ppm in a wide range of temperatures, between 5 and 95 °C, while the last two were obtained at 25 °C. As a result of this study, it has been concluded that the presence of water is critical in those physical properties that involve mass or charge transport processes, resulting in the finding that the absolute value of the average percentage change in both viscosity and electrical conductivity is above 40%. Meanwhile, refractive index (≤0.3%), density (≤0.5%) and surface tension (≤2%) present much less significant changes.

Study of the Reaction of Hydroxylamine with Iridium Atomic and Cluster Anions (n = 1-5).

Elucidating the multifaceted processes of molecular activation and subsequent reactions gives a fundamental view into the development of iridium catalysts as they apply to fuels and propellants, for example, for spacecraft thrusters. Hydroxylamine, a component of the well-known hydroxylammonium nitrate (HAN) ionic liquid, is a safer alternative and mimics the chemistry and performance standards of hydrazine. The activation of hydroxylamine by anionic iridium clusters, Irn- (n = 1-5), depicts a part of the mechanism, where two hydrogen atoms are removed, likely as H2, and Irn(NOH)- clusters remain. The significant photoelectron spectral differences between these products and the bare clusters illustrate the substantial electronic changes imposed by the hydroxylamine fragment on the iridium clusters. In combination with DFT calculations, a preliminary reaction mechanism is proposed, identifying the possible intermediate steps leading to the formation of Ir(NOH)-.

Thermal Stability and Decomposition Kinetics of 1-Alkyl-2,3-Dimethylimidazolium Nitrate Ionic Liquids: TGA and DFT Study.

The thermal stability and decomposition kinetics analysis of 1-alkyl-2,3-dimethylimidazole nitrate ionic liquids with different alkyl chains (ethyl, butyl, hexyl, octyl and decyl) were investigated by using isothermal and nonisothermal thermogravimetric analysis combined with thermoanalytical kinetics calculations (Kissinger, Friedman and Flynn-Wall-Ozawa) and density functional theory (DFT) calculations. Isothermal experiments were performed in a nitrogen atmosphere at 240, 250, 260 and 270 °C. In addition, the nonisothermal experiments were carried out in nitrogen and air atmospheres from 30 to 600 °C with heating rates of 5, 10, 15, 20 and 25 °C/min. The results of two heating modes, three activation energy calculations and density functional theory calculations consistently showed that the thermal stability of 1-alkyl-2,3-dimethylimidazolium nitrate ionic liquids decreases with the increasing length of the alkyl chain of the substituent on the cation, and then the thermal hazard increases. This study could provide some guidance for the safety design and use of imidazolium nitrate ionic liquids for engineering.

Proline nitrate ionic liquid as high temperature acid corrosion inhibitor for mild steel: Experimental and molecular-level insights

• Anticorrosive impact of [Pro][NO 3 ] IL tested for mild steel. • At 70 °C inhibition capability of the compound was 93.88% at 300 ppm. • Surface morphology by SEM and XPS confirmed considerable surface change. • Various isotherm models supported the adsorption mechanism. • DFT and MC simulation underpinned the experimental findings. The synthesis of novel l -proline nitrate ionic liquid referred to as [Pro][NO 3 ] (IL), was performed and the 1 H, 13 C NMR, and FT-IR spectroscopic techniques were used to elucidate the chemical structure. The inhibition properties of the [Pro][NO 3 ] IL were evaluated for mild steel (MS) corrosion in 1 M HCl using gravimetric measurement, electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (PDP) measurement, FT-IR spectroscopy, X-ray photoelectron spectroscopy (XPS), contact angle measurement, scanning electron microscopy (SEM), density functional theory (DFT) and Monte Carlo (MC) simulation studies. As indicated by electrochemical and weight loss techniques the tested [Pro][NO 3 ] IL was established as an excellent mixed type high-temperature acid corrosion inhibitor for MS; the optimal temperature and concentration being 70 °C and 300 ppm, respectively. Furthermore, the contact angle measurement and surface studies revealed water-repelling property and the protecting capability, respectively of the investigated inhibitor. The electronic property of [Pro][NO 3 ] IL has been explored using density functional theory (DFT) and the sites susceptible for electron sharing were identified through Fukui indices analysis. Furthermore, molecular dynamics simulation based on the Monte Carlo method has been employed to envisage the spontaneous adsorption of [Pro][NO 3 ] IL on MS surface.

L-Alanine methyl ester nitrate ionic liquid: synthesis, characterization and anti-corrosive application

The inhibition effect of amino acid-based ionic liquid (IL), L-Alanine methyl ester nitrate referred to as L-AlaC1NO3 IL on the corrosion of mild steel (MS) in 1 M HCl was investigated by weight loss and electrochemical measurements at temperatures ranging from 30 °C to 60 °C. The percentage inhibition effieicency increased with the increase of the concentration of the inhibitor and reached about 66.1% at the concentration of 0.003 M at 30 °C. On the other hand, the percentage inhibition increased with the increase of temperature and reached 84.0% at 60 °C on the same inhibitor concentration. Furthermore, the contact angle measurement and surface studies revealed water-repelling property and the protecting capability of the investigated inhibitor. The electronic property of L-AlaC1NO3 IL has been explored using density functional theory (DFT) and the sites susceptible for electron sharing were identified through Fukui indices analysis. Additionally, the Monte Carlo approach in molecular dynamics simulation evidenced the spontaneity of inhibitor’s interaction onto MS surface through donor–acceptor interactions leading towards flat-lying adsorption orientation.

The exhaust emission characteristics of a water-emulsified diesel/sunflower oil blend fuel by ionic liquid surfactants

A fuel microemulsion based on blend of diesel fuel:sunflower oil (4:1), water, 1-butanol (co-surfactant), and a blend of Tween 80, Span 80 and 1-buthyl-3-methylimidazolium nitrate ionic liquid as surfactant is formulated and optimized regarding the amounts of co-surfactant, water and oily phase. The fuel microemulsions were for upto one year stable on the bench and their density and viscosity were comparable to neat diesel fuel. The size of water droplets in fuel microemulsions are measured by dynamic light scattering (about 10 nm) with a very narrow size distribution. The optimum results are obtained by using a blend of Span 80:Tween 80:1-buthyl-3-methylimidazolium nitrate, 70:26.25:3.75, respectively, as surfactant. The engine combustion tests at various engine speeds and full load indicated that the brake-specific fuel consumption, torque, brake power and exhaust gas temperature are decreased in fuel microemulsion compared to neat diesel fuel. Carbon dioxide and nitrogen oxide emissions were reduced by 4–5%, and unburned hydrocarbons and carbon monoxide emissions were increased by 18.4% and 1.18%, respectively, for optimum fuel microemulsion compared to neat diesel fuel. The results are promising to introduce a way to improve the diesel fuel performance in terms of its environmental impacts.

The separation of thorium and rare earth elements using [A336][NO3]: insight into a new extraction mechanism

In this study, extraction and separation of thorium(IV) and a few representative rare earths in HNO3 media was evaluated using trioctylmethylammonium nitrate ([A336][NO3]) ionic liquid. An unexpected novel extraction mechanism was identified based on the studies in the slope analysis and ESI–MS spectrum. The trimer of [A336][NO3] was confirmed to dominate the extraction reaction by ESI–MS spectrum before and after the extraction. The extraction efficiency of La(III), Eu(III) and Lu(III) by [A336][NO3] are much lower than Th(IV) in acid medium, which means that it is possible to separate thorium from rare earths or the rare earth ores by using [A336][NO3].

Effect of rotating magnetic field on the diffusivity of ethylammonium nitrate ionic liquid confined between micrometer-spaced glass plates

We studied changes in the diffusion coefficients in layers of EAN confined between glass plates, placed in a strong magnetic field with a magnetic flux density B0, and rotated around the axis directed along and normal to B0. Under the rotational conditions along B0, the diffusion coefficient decreases with time after placement in the magnetic field at the same rate as for a static sample, observed previously (Filippov and Antzutkin, Phys. Chem. Chem. Phys. 2018. 20. 6316). However, when the EAN layers are rotating around the axis perpendicular to B0, the duration of exposure to the magnetic field does not affect the diffusion coefficient until the rotation stops. On the other hand, the diffusivity after extended exposure to a static magnetic field increases as the sample starts to rotate around the axis perpendicular to B0. The observed effects are due to either the periodic change in the orientation of the thin surface layers of EAN or inhomogeneity of B0 in the sample due to the B0 fluctuation.

Ionic Liquid Clusters Generated from Electrospray Thrusters: Cold Ion Spectroscopic Signatures of Size-Dependent Acid–Base Interactions

We determine the intramolecular distortions at play in the 2-hydroxyethylhydrazinium nitrate (HEHN) ionic liquid (IL) propellant, which presents the interesting case that the HEH+ cation has multiple sites (i.e., hydroxy, primary amine, and secondary ammonium groups) available for H-bonding with the nitrate anion. These interactions are quantified by analyzing the vibrational band patterns displayed by cold cationic clusters, (HEH+)n(NO3-)n-1, n = 2-6, which are obtained using IR photodissociation of the cryogenically cooled, mass-selected ions. The strong interaction involving partial proton transfer of the acidic N-H proton in HEH+ cation to the nitrate anion is strongly enhanced in the ternary n = 2 cluster but is suppressed with increasing cluster size. The cluster spectra recover the bands displayed by the bulk liquid by n = 5, thus establishing the minimum domain required to capture this aspect of macroscopic behavior.

Temperature dependence of 1H NMR chemical shifts and diffusivity of confined ethylammonium nitrate ionic liquid

Some ionic liquids (ILs) change their dynamic properties when placed in a confinement between polar surfaces (Filippov et al., Phys. Chem. Chem. Phys. 2018, 20, 6316). The diffusivities of ions and NMR relaxation times in these ILs also reversibly change under a strong static magnetic field. The mechanisms of these phenomena are not clear, but it has been suggested that they involve modified hydrogen-bonding networks formed in these ILs in the presence of polar surfaces. To obtain a better understanding of these effects, we performed temperature-dependent measurements of chemical shifts and diffusion coefficients for ethylammonium nitrate (EAN) IL in the bulk phase (IB) and confined in layers with a thickness of ~4 μm between quartz plates unexposed (I phase) and exposed (IMF phase) to a static magnetic field of 9.4 T. It was shown that the NMR chemical shift of NH3 protons of EAN in the I phase is strongly shifted upfield, ~0.0145 ppm/K, which is due to weakening of the hydrogen-bonding network of the confined EAN. Exposure to the magnetic field leads to restitution of the hydrogen-bonding (H-bonding network). The temperature dependences of diffusion coefficients follow the order D(I) > D(IB) > D(IMF) and can be described by a Vogel-Fulcher-Tammann approach with variation of the pre-exponential factor, which is determined by the strength of the H-bonding network. Confinement of EAN between plates (IB → I) is an endothermic process, while processes occurring in a magnetic field, I → IMF and IMF → I, are exothermic and endothermic, respectively.

L-Proline based ionic liquid: A highly efficient and homogenous catalyst for synthesis of 5-benzylidene-1,3-dimethylpyrimidine-2,4,6(1H,3H,5H)-trione and pyrano[2,3-d] pyrimidine diones under ultrasonic irradiation

A catalytic, practical, efficient procedure for the synthesis of 5-benzylidene-1,3-dimethylpyrimidine-2,4,6(1H,3H,5H)-trione and pyrano[2,3-d] pyrimidine diones at room temperature was developed using L-Proline nitrate ionic liquid under ultrasonic irradiation. The L-Proline nitrate is homogeneous and green catalyst easy to prepare by mixing L-Proline and nitric acid possess excellent catalytic activity under standard ultrasonic bath at room temperature for the synthesis of pyrimidine core. This adequate procedure offers some advantages like the use of green solvent H2O, environmentally green benign procedure, excellent yields, simple procedure, short reaction times, no need for column chromatographic separation and reusability of catalyst for five subsequent reaction.

Hydration counteracts the separation of lanthanides by solvent extraction.

The extraction of lanthanides from aqueous nitrate solutions by quaternary ammonium nitrate ionic liquids (e.g., [A336][NO3]) shows a negative sequence (i.e., light lanthanides are more efficiently extracted than heavy lanthanides), which conflicts with the lanthanide contraction. In this study, we explored the origin of the negative sequence by investigating the extraction of lanthanides from ethylammonium nitrate by [A336][NO3]. The extraction shows a positive sequence, which is converted to a negative sequence with the addition of water. The transformation from positive to negative sequences reveals that the negative sequence is caused by the hydration of lanthanide ions: hydration of lanthanide ions counteracts the extraction. Therefore, the use of solvents that have weak solvation with lanthanide ions might enhance the separation of the elements by solvent extraction.