Density and isothermal compressibility for two trialkylimidazolium-based ionic liquids at temperatures from (278 to 398) K and up to 120 MPa

In this paper, a densimeter based on vibrating tube principle is used to determine experimentally the density of 1-butyl-2,3-dimethylimidazolium tris(pentafluoroethyl)trifluorophosphate and 1-butyl-2,3-dimethylimidazolium bis(trifluoromethylsulfonyl)imide at temperatures between (278.15 and 398.15) K and at pressures up to 120 MPa. The apparatus was calibrated by using water, vacuum and bromobenzene. The Tammann–Tait equation of state was used to correlate (p, T, ρ) results with standard deviations around 2 · 10⁻⁴ g · cm⁻³. Other volumetric properties, such as isothermal compressibility and isobaric thermal expansivity, were obtained from this equation. For each ionic liquid, the α_p isotherms present a crossing point within the experimental pressure range. Besides, the effect that the C2-methylation in the imidazolium cation provokes on density values is analyzed. The prediction ability of the group contribution methods of Gardas and Coutinho and Jacquemin et al. were tested with the experimental densities.     

A new measure of orthogonality for multi-dimensional chromatography

Multi-dimensional chromatographic techniques, such as (comprehensive) two-dimensional liquid chromatography and (comprehensive) two-dimensional gas chromatography, are increasingly popular for the analysis of complex samples, such as protein digests or mineral oils. The reason behind the popularity of these techniques is the superior performance, in terms of peak-production rate (peak capacity per unit time), that multi-dimensional separations offer compared to their one-dimensional counterparts. However, to fully utilize the potential of multi-dimensional chromatography it is essential that the separation mechanisms used in each dimension be independent of each other. In other words, the two separation mechanisms need to be orthogonal. A number of algorithms have been proposed in the literature for measuring chromatographic orthogonality. However, these methods have their limitations, such as reliance on the division of the separation space into bins, need for specialist software or requirement of advanced programming skills. In addition, some of the existing methods for measuring orthogonality include regions of the separation space that do not feature peaks. In this paper we introduce a number of equations which provides information on the spread of the peaks within the separation space in addition to measuring orthogonality, without the need for complex computations or division of the separation space into bins.     

H2O + Fe(NO3)3 + Ni(NO3)2 ternary system isotherms at 0 °C and 30 °C

H₂O + Ni(NO₃)₂ binary system were investigated in the temperature range from −25 °C to 55 °C. The solid-liquid equilibria of the ternary system H₂O + Fe(NO₃)₃ + Ni(NO₃)₂ were studied using a synthetic method based on conductivity measurements. Tow isotherms were established at 0 °C and 30 °C, and the appearing stable solid phases are iron nitrate nonahydrate (Fe(NO₃)₃·9H₂O), iron nitrate hexahydrate (Fe(NO₃)₃·6H₂O), nickel nitrate hexahydrate (Ni(NO₃)₂·6H₂O) and nickel nitrate tetrahydrate (Ni(NO₃)₂·4H₂O).     

Liquid density of oxygenated additives to biofuels: 2-Butanol at pressures up to 140 MPa and temperatures from (293.15 to 393.27) K

This work reports new density data (159 points) of 2-butanol at seven temperatures between (293.15 and 393.27) K and 23 pressures from (0.1 to 140) MPa (every 5 or 10 MPa). An Anton Paar vibrating tube densimeter, calibrated with an uncertainty of ±0.7 · 10⁻³ g · cm⁻³, was used to perform these measurements. The experimental density data were fitted with the Tait-like equation with low standard deviations. In addition, the isobaric thermal expansivity and the isothermal compressibility have been derived from the Tait-like equation.     

A New Succinato‐bridged Supramolecular Helix Chain: Crystal Structure of [Mn(H2O)2(bpy)(C4H4O4)] · H2O with bpy = 2,2′‐bipyridine

Yellow crystals of [Mn(H₂O)₂(bpy)(C₄H₄O₄)] · H₂O were obtained by the reaction of 2,2′‐bipyridine, succinic acid, MnSO₄ · H₂O and Na₂CO₃ in an aqueous methanol solution. The crystal structure (monoclinic, P2₁/c (no. 14), a = 8.294(1), b = 11.556(1), c = 17.064(1)Å, β = 95.181(6)°, Z = 4, R = 0.0349, wR² = 0.0887) consists of 1D supramolecular helix chains [Mn(H₂O)₂(bpy)(C₄H₄O₄)_2/2] and hydrogen bonded H₂O molecules. The Mn atoms are octahedrally coordinated by two N atoms of one bidentate chelating bpy ligand and four O atoms of two H₂O molecules and two bis‐monodentate bridging succinato ligands with d(Mn–O) = 2.139–2.237Å and d(Mn–N) = 2.268, 2.281 Å. The helix chains are held together by π‐π stacking interactions and hydrogen bonds.     

Convex hull: A new method to determine the separation space used and to optimize operating conditions for comprehensive two-dimensional gas chromatography

It is important to develop methods of optimizing the selection of column sets and operating conditions for comprehensive two-dimensional gas chromatography. A new method for the calculation of the percentage of separation space used was developed using Delaunay's triangulation algorithms (convex hull). This approach was compared with an existing method and showed better precision and accuracy. It was successfully applied to the selection of the most convenient column set and the geometrical parameters of second column for the analysis of 49 target compounds in wastewater.     

Hybrid plasma bonding for void-free strong bonded interface of silicon/glass at 200 °C

A novel hybrid plasma bonding (HPB) that combines sequential plasma activation (reactive ion etching followed by microwave radicals) with anodic bonding has been developed to achieve void-free and strong silicon/glass bonding at low temperature. The interfacial voids were observed at the silicon/glass interface both in the anodic bonding and in the plasma activated anodic bonding, but the voids were completely disappeared in the HPB method at 200 °C. The bonding strength of the silicon/glass in the HPB was as high as 30 MPa at 200 °C, which was higher than that in the individual treatment of anodic and plasma activated bonding methods. The improved characteristic behavior of the interface in the HPB is attributed to the higher hydrophilicity and smooth surfaces of silicon and glass after sequential plasma activation. These highly reactive and clean surfaces enhance the mobility of alkaline cations from the glass surface across the interface toward the bulk of glass in the HPB. This transportation resulted in a ∼353 nm thick alkaline depletion layer in the glass and enlarged the amorphous SiO₂ across the interface. The void-free strong bonding is attributed to the clean hydrophilic surfaces and the amorphous SiO₂ layer across the interface.     

Preparation of higher flux NaA zeolite membrane on asymmetric porous support and permeation behavior at higher temperatures up to 145 °C in vapor permeation

NaA zeolite membranes were synthesized on an asymmetric porous alumina support with a lower mass-flow resistance for development of more economically feasible membranes with higher permeation performance. The support influence on permeation fluxes through the membrane using asymmetric support was investigated by vapor permeation at 100–145 °C in a mixture of water (10 wt.%)/ethanol (90 wt.%) in which the higher permeation fluxes up to 37 kg m⁻² h⁻¹ or water permeances up to 3.2 × 10⁻⁶ mol m⁻² s⁻¹ Pa⁻¹at 145 °C were observed. The performance was higher than those in the previously reported NaA membrane on a monolayer porous alumina support of 31 kg m⁻² h⁻¹ or water permeances of 2.5 × 10⁻⁶ mol m⁻² s⁻¹ Pa⁻¹at 145 °C. These results are experimental evidence to show the effect of asymmetric support utilization in membrane preparation on the higher membrane performance. The estimate of the pressure drop over the both types of support indicates that the improvement of higher permeation fluxes in the asymmetric type membrane could be attributed to the suppression of pressure drop in the support layer due to lower mass-flow resistance there.     

A new equation to reproduce the enthalpies of transfer of formamide, N-methylformamide and N,N-dimethylformamide from water to aqueous methanol mixtures at 298 K

The enthalpies of transfer of formamide (Form) N-methylformamide (NMF) and N,N-dimethylformamide (DMF) from water to aqueous methanol mixtures are reported and analysed in terms of the new solvation theory. It was found that a previous equation could not reproduce these data over the whole range of solvent compositions. Using the new solvation theory to reproduce the enthalpies of transfer shows excellent agreement between the experimental and calculated data over the entire range of solvent compositions. The analyses show that the solvation of DMF is random in the aqueous methanol mixtures while Form and NMF are preferentially solvated by methanol. It is also found that the interaction of the solutes is stronger with methanol than with water.     

A Zipper‐like Supramolecular Double‐Chain based on 1 D π‐π Stacking Interactions: Synthesis and Crystal Structure of [Cu(phen)(C4H4O4)(H2O)]2 · C4H6O4 (phen = 1,10‐phenanthroline)

[Cu(C₁₂H₈N₂)(C₄H₄O₄)(H₂O)]₂ · C₄H₆O₄ was prepared by the reaction of succinic acid, CuCl₂ · 2 H₂O, 1,10‐phenanthroline (phen = C₁₂H₈N₂), and Na₂CO₃ in a CH₃OH–H₂O solution. The crystal structure (triclinic, P 1 (no. 2), a = 7.493(1), b = 9.758(1), c = 13.517(1) Å; α = 68.89(1)°, β = 88.89(1)°, γ = 73.32(1)°, Z = 1, R = 0.0308, wR² = 0.0799 for 3530 observed reflections (F ≥ 2σ(F ) out of 3946 unique reflections) consists of hydrogen bonded succinic acid molecules and succinato bridged 1 D zipperlike supramolecular [Cu(phen)(C₄H₄O₄)_2/2(H₂O)]₂ double chains based on 1 D π‐π stacking interactions between the chelating phen systems at distances of 3.71 Å and 3.79 Å. The Cu atoms are fivefold trigonal bipyramidally coordinated by two N atoms of the bidentate chelating phen ligand and three O atoms of one water molecule and two bidentate bridging succinate ligands. The water O atom and one phen N atom are at the apical positions (equatorial: d(Cu–O) = 1.945, 2.254(2) Å, d(Cu–N) = 2.034(2) Å; axial: d(Cu–O) = 1.971(2) Å, d(Cu–N) = 1.995 Å).     

Liquid density of biofuel mixtures: 1-Heptanol + heptane system at pressures up to 140 MPa and temperatures from 298.15 K to 393.15 K

This work reports new experimental density data (954 points) for binary mixtures of 1-heptanol + heptane over the composition range (seven compositions; 0 ⩽ 1-heptanol mole fraction x ⩽ 1), between 298.15 and 393.15 K, and for 23 pressures from 0.1 MPa up to 140 MPa. An Anton Paar vibrating tube densimeter, calibrated with an uncertainty of ±0.7 kg · m⁻³ was used to perform these measurements. The experimental density data were fitted with a Tait-like equation with low standard deviations. Excess volumes have been calculated from the experimental data. In addition, the isobaric thermal expansivity and the isothermal compressibility have been derived from the Tait-like equation, provided as supplementary material.     

Trilinearity deviation ratio: A new metric for chemometric analysis of comprehensive two-dimensional gas chromatography time-of-flight mass spectrometry data

Comprehensive two-dimensional gas chromatography coupled with time-of-flight mass spectrometry (GC × GC–TOFMS) is a well-established instrumental platform for complex samples. However, chemometric data analysis is often required to fully extract useful information from the data. We demonstrate that retention time shifting from one modulation to the next, Δ²t_R, is not sufficient alone to quantitatively describe the trilinearity of a single GC × GC–TOFMS run for the purpose of predicting the performance of the chemometric method parallel factor analysis (PARAFAC). We hypothesize that analyte peak width on second dimension separations, ²W_b, also impacts trilinearity, along with Δ²t_R. The term trilinearity deviation ratio, TDR, which is Δ²t_R normalized by ²W_b, is introduced as a quantitative metric to assess accuracy for PARAFAC of a GC × GC–TOFMS data cube. We explore how modulation ratio, M_R, modulation period, P_M, temperature programming rate, T_ramp, sampling phase (in-phase and out-of-phase), and signal-to-noise ratio, S/N, all play a role in PARAFAC performance in the context of TDR. Use of a P_M in the 1–2 s range provides an optimized peak capacity for the first dimension separation (500–600) for a 30 min run, with an adequate peak capacity for the second dimension separation (12–15), concurrent with an optimized two-dimensional peak capacity (6000–7500), combined with sufficiently low TDR values (0–0.05) to facilitate low quantitative errors with PARAFAC (0–0.5%). In contrast, use of a P_M in the 5 s or greater range provides a higher peak capacity on the second dimension (30–35), concurrent with a lower peak capacity on the first dimension (100–150) for a 30 min run, and a slightly reduced two-dimensional peak capacity (3000–4500), and furthermore, the data are not sufficiently trilinear for the more retained second dimension peaks in order to directly use PARAFAC with confidence.     

Aqueous Batteries Operated at −50 °C

Insufficient ionic conductivity and freezing of the electrolyte are considered the main problems for electrochemical energy storage at low temperatures (low T). Here, an electrolyte with a freezing point lower than ?130 °C is developed by using dimethyl sulfoxide (DMSO) as an additive with molar fraction of 0.3 to an aqueous solution of 2 m NaClO₄ (2M‐0.3 electrolyte). The 2M‐0.3 electrolyte exhibits sufficient ionic conductivity of 0.11 mS cm^?1 at ?50 °C. The combination of spectroscopic investigations and molecular dynamics (MD) simulations reveal that hydrogen bonds are stably formed between DMSO and water molecules, facilitating the operation of the electrolyte at ultra‐low T. Using DMSO as the electrolyte additive, the aqueous rechargeable alkali‐ion batteries (AABs) can work well even at ?50 °C. This work provides a simple and effective strategy to develop low T AABs.     

High-temperature two-dimensional gas chromatography of hydrocarbons up to nC60 for analysis of vacuum gas oils

In a tense energetic context, the characterization of heavy petroleum fractions becomes essential. Conventional comprehensive two-dimensional gas chromatography (2D-GC or GC × GC) is widely used for middle distillates analysis, but only a few applications are devoted to these heavier fractions. In this paper, it is shown how the optimization of GC × GC separation allowed the determination of suitable high-temperature (HT) conditions, adjusting column properties and operating conditions. 2D separations were evaluated using 2D separation criteria and a new concept of 2D asymmetry (As_2D). New HT conditions allowed the extension of GC × GC range of applications to heavier hydrocarbons, up to nC₆₀. A first application of high-temperature two-dimensional gas chromatography (HT-2D-GC) to a full vacuum gas oil (VGO) feed stock is described. Comparisons with other standardized methods illustrate the high potential of HT-2D-GC for heavy fractions analysis.     

A Fullerene‐Based Molecular Torsion Balance for Investigating Noncovalent Interactions at the C60 Surface

To investigate the nature and strength of noncovalent interactions at the fullerene surface, molecular torsion balances consisting of C₆₀ and organic moieties connected through a biphenyl linkage were synthesized. NMR and computational studies show that the unimolecular system remains in equilibrium between well‐defined folded and unfolded conformers owing to restricted rotation around the biphenyl C?C bond. The energy differences between the two conformers depend on the substituents and is ascribed to differences in the intramolecular noncovalent interactions between the organic moieties and the fullerene surface. Fullerenes favor interacting with the π‐faces of benzenes bearing electron‐donating substituents. The correlation between the folding free energies and corresponding Hammett constants of the substituents in the arene‐containing torsion balances reflects the contributions of the electrostatic interactions and dispersion force to face‐to‐face arene–fullerene interactions.     

Bioplastic biodegradation activity of anaerobic sludge prepared by preincubation at 55 °C for new anaerobic biodegradation test

The new method to evaluate the anaerobic biodegradability of bioplastics, such as polycaprolactone (PCL) and poly (lactic acid) (PLA), under aquatic (slurry) conditions at 55 °C is applying. For this method, we prepared the sludge at 55 °C from the sludge at 37 °C by the method in which the sludge from the real tank operating at around 37 °C using cow manure and vegetable waste as the feed stock was preincubated at 55 °C. It was unknown at which stage the sludge during preincubation has the optimized anaerobic biodegradation activity of plastics. Four different stage sludges during preincubation (the sludge at 7 days after the start of preincubation at 55 °C, at 12 days, at 18 days, and at 40 days) were compared by the anaerobic biodegradation activity of PLA. The preincubated sludge at around 18 days (a gradual decrease in biogas evolution and a methane ratio over 60%) showed the highest biodegradation activity of PLA. In addition, the bacterial population in each sludge was analyzed by the denaturing gradient gel electrophoresis (DGGE) analysis of the amplified 16S rRNA gene fragments, however, the newly grown bacteria bands at 55 °C were not clearly detected.     

(p, ρ, T) properties, and apparent molar volumes V? of ZnBr2 in methanol at T = (298.15 to 398.15) K and pressures up to p = 40 MPa

The (p, ρ, T) properties of pure methanol, the (p, ρ, T) properties and apparent molar volumes V_? of ZnBr₂ in methanol at T = (298.15 to 398.15) K and pressures up to p = 40 MPa are reported, and apparent molar volumes have been evaluated. The experimental (p, ρ, T, m) values were described by an equation of state. For the solutions the experiments were carried out at molalities m = (0.05772, 0.37852, 0.71585 and 1.95061) mol · kg⁻¹ of zinc bromide.     

(p, Vm, T) measurements of (cyclohexane + nonane) at temperatures from 298.15 K to 328.15 K and at pressures up to 40 MPa

The densities and speeds of sound of (cyclohexane + nonane) were measured at four temperatures from 298.15 K to 328.15 K, and the respective values of excess volumes and adiabatic compressibility were calculated. Thereafter, the densities for the last system were measured at elevated pressures (0.1 to 40) MPa at four temperatures over the range 298.15 K to 328.15 K with a high-pressure apparatus. The high-pressure density data were fitted to the Tait equation and the isothermal compressibilities were calculated with a novel procedure with the aid of this equation. The low- and high-pressure values of calculated from the density data show that the deviations from ideal behaviour in the system decrease slightly as the temperature and pressure are raised. The data were fitted to the fourth-order Redlich-Kister equation, with the maximum likelihood principle being applied for the determination of the adjustable parameters.     

Characterization of new types of stationary phases for fast and ultra-fast liquid chromatography by signal processing based on AutoCovariance Function: A case study of application to Passiflora incarnata L. extract separations

In this study, a comparative investigation was performed of HPLC Ascentis^® (2.7 μm particles) columns based on fused-core particle technology and Acquity^® (1.7 μm particles) columns requiring UPLC instruments, in comparison with Chromolith™ RP-18e columns. The study was carried out on mother and vegetal tinctures of Passiflora incarnata L. on one single or two coupled columns. The fundamental attributions of the chromatographic profiles are evaluated using a chemometric procedure, based on the AutoCovariance Function (ACVF). Different chromatographic systems are compared in terms of their separation parameters, i.e., number of total chemical components (m_tot), separation efficiency (σ), peak capacity (n_c), overlap degree of peaks and peak purity. The obtained results show the improvements achieved by HPLC columns with narrow size particles in terms of total analysis time and chromatographic efficiency: comparable performance are achieved by Ascentis^® (2.7 μm particle) column and Acquity^® (1.7 μm particle) column requiring UPLC instruments. The ACVF plot is proposed as a simplified tool describing the chromatographic fingerprint to be used for evaluating and comparing chemical composition of plant extracts by using the parameters D% – relative abundance of the deterministic component – and c_EACF – similarity index computed on ACVF.