Bubble points of the systems isopropanol–water,isopropanol–water–sodium acetate and isopropanol–water–sodium oleate at high pressure

Supercritical water oxidation (SCWO) is a powerful technology for destroying organic wastes with high removal efficiencies. Corrosion and salt deposition are the main challenges for the industrial development of the SCWO process. In SCWO heteroatoms are oxidized until high oxidation states: oxides, acids or salts. If there are enough cations, the heteroatoms precipitate as salts and eventually can be recovered. Cations can be introduced in the system by adding organic salts to the feed. The organic part of the salt is oxidized to CO₂ and water, and the cations remain free to join the free anions and precipitate as inorganic salts. The thermodynamic study of this system it is very interesting for future modeling of the SCWO process.Bubble points of the systems isopropanol (IPA)–water, IPA–water–sodium acetate and IPA–water–sodium oleate were determined in the temperature range (396 and 460 K), pressures higher than 0.35 MPa, with IPA concentrations lower than 5 mol% and salt concentrations of 5 and 8.2 mol% for sodium acetate, and 0.11 and 0.25 mol% for sodium oleate. Bubble points were determined using a Cailletet apparatus that operates with the synthetic method.As expected, the vapor pressure of the system increases as IPA concentration is increased, and in general decreases when salt concentration increases. The measured vapor pressures of mixtures of water and IPA were consistent with literature data.The experimental data were correlated using the Anderko–Pitzer EoS, which was specially developed for water–salt systems at high temperatures and pressures. Densities and vapor pressures of IPA and the experimental data presented in this work were used for obtaining the parameters of the EoS in the range of pressure and temperature of the data. In the range of temperature and concentration considered, the average deviations between experimental and calculated vapor pressures were %ΔP = 1.18% for the system IPA–water, %ΔP = 4.03% for the system IPA–water–NaAc and %ΔP = 2.77% for the system IPA–water–NaOl.     

Amidinium salts: Towards enabling electrochemistry in non-polar media from alkanes to ionic liquids

There is little known about electrochemical behavior in non-polar media due to lack of compatible, hydrophobic salts. In this work, this difficult challenge has been overcome by following a strategy based on designing and synthesizing a novel family of organic salts with highly-delocalized cations and anions. The salts are based on the amidinium cation with highly-delocalized positive charge and long alkyl groups that enable good miscibility in heptane, an archetypical, non-polar media, while being hydrophobic, room-temperature ionic liquids. The electrolyte solutions show ionic conductivities that span the range 10^− 11–10^− 4 S cm^− 1 and electrochemical activity which enable their application as antistatic agents and also as new type of hydrophobic electrolytes in various electrochemical devices.     

Triggering phase disengagement of 1-alkyl-3-methylimidazolium chloride ionic liquids by using inorganic and organic salts

This study deals with the influence of different inorganic and organic salts made up with sodium, potassium and ammonium cations to induce phase segregation in aqueous solutions of C₈C₁imCl and C₁₀C₁imCl at T = 298.15 K. The experimental solubility values are described by means of four empirical equations and the suitability of the models was analysed in the light of the standard deviation. The capability of the above mentioned salts to further phase de-mixing is discussed on the basis of their different molar Gibbs free energy of hydration (Δ_hydG), molar entropy of hydration (Δ_hydS) and pH. The efficiency of the separation was evaluated by determining the tie-lines, and these experimental values were fitted to three known models such as Bancroft, Othmer–Tobias and modified Setschenow equations.     

Thermodynamic and transport properties of (1-Butanol + 1,4-Butanediol) at temperatures from (298.15 to 318.15) K

Densities and kinematic viscosities have been measured for (1-butanol + 1,4-butanediol) over the temperature range from (298.15 to 318.15) K. The speeds of sound within the temperature range from (293.15 to 318.15) K have been measured as well. Using these results and literature values of isobaric heat capacities, the molar volumes, isentropic and isothermal compressibility coefficients, molar isentropic and isothermal compressibilities, isochoric heat capacities as well as internal pressures were calculated. Also the corresponding excess and deviation values (excess molar volumes, excess isentropic and isothermal compressibility coefficients, excess molar isentropic and isothermal compressibilities, different defined deviation speed of sound and dynamic viscosity deviations) were calculated. The excess values are negative over the whole concentration and temperature range. The excess and deviation values are expressed by Redlich–Kister polynomials and discussed in terms of the variations of the structure of the system caused by the participation of the two different alcohol molecules in the dynamic intermolecular association process through hydrogen bonding at various temperatures. The predictive abilities of Grunberg–Nissan and McAllister equations for viscosities of mixtures have also been examined.     

Solubilities of imidazolium-based ionic liquids in aqueous salt solutions at 298.15 K

The solubilities of ionic liquids in the ternary systems (ionic liquid + H₂O + inorganic salt) were reported at 298.15 K and atmospheric pressure. The examined ionic liquids are [C₄mim][PF₆] (1-n-butyl-3-methylimidazolium hexafluorophosphate), [C₈mim][PF₆] (1-n-octyl-3-methylimidazolium hexafluorophosphate), and [C₈mim][BF₄] (1-n-octyl-3-methylimidazolium tetrafluoroborate). The examined inorganic salts are the chloride-based salts (sodium chloride, lithium chloride, potassium chloride, and magnesium chloride) and the sodium-based salts (sodium thiocyanate, sodium nitrate, sodium trifluoroacetate, sodium bromide, sodium iodide, sodium perchlorate, sodium acetate, sodium hydroxide, sodium dihydrogen phosphate, sodium phosphate, sodium tetrafluoroborate, sodium sulfate, and sodium carbonate). The effects of the cations and the anions of the ionic liquids and of the inorganic salts on the solubility of the ionic liquids in the ternary solutions were systematically compared and discussed.     

Salt effects on the partition coefficients of phenol in two-phase mixtures of water and carbon dioxide at pressures from (8 to 30) MPa at a temperature of 313 K

Partition coefficients K_c of phenol between an aqueous solution containing different salts and a compressed CO₂ phase have been determined at T=313 K. For NaCl and (CH₃)₄NBr a pressure range from 8 MPa to around 30 MPa was investigated, for KCl and NaBr measurements were performed at a pressure of 22 MPa. The salt concentration has been varied between (0.25 and 3.0) mol·dm⁻³. With increasing pressure a rise in K_c is observed which typically is also found in systems free of salt. Salting-out was observed for the alkali salts, salting-in has been found for the ammonium salt, both effects increased with increasing salt concentration. From the concentration dependence of the K_c values Setschenow coefficients k_S have been derived. At p>10 MPa values are obtained as found in two phase mixtures of water with other organic solvents at ambient pressure. This conclusion was confirmed with both literature and own experimental data in the case of salting-out by NaCl as well as for the salting-in by (CH₃)₄NBr from measurements with phenol in (water + cyclohexane) at T=313 K.     

(Liquid + liquid) equilibria of polymer-salt aqueous two-phase systems for laccase partitioning: UCON 50-HB-5100 with potassium citrate and (sodium or potassium) formate at 23 °C

Aqueous two-phase systems (ATPS) are recognized as very suitable techniques for the recovery of target solutes in biological applications. Three new phase diagrams of (UCON 50-HB-5100 + potassium citrate + water), (UCON 50-HB-5100 + sodium formate + water), and (UCON 50-HB-5100 + potassium formate + water) systems were measured at 23 °C. The binodal curves were successfully described using the empirical equation suggested by Merchuk and co-workers. The reliability of the tie-line data experimentally determined was evaluated using the equations reported by Othmer–Tobias and Bancroft and satisfactory linearity was obtained for all ATPS. Among the salts studied, potassium citrate proved to be the most effective in ATPS formation, providing the largest heterogeneous region. Besides, the effect of both anions and cations in the size of the heterogeneous region and in the slope of the tie-lines has been compared. For the same salts and conditions, the heterogeneous region using UCON as the phase-forming polymer is larger than using polyethylene glycol. Furthermore, laccase partition in the UCON-salt ATPS was studied and it was found that in all cases enzyme partition occurred preferably to the bottom phase (salt-rich phase). Laccase concentration in the salt-rich phase was approximately 2-fold that in the top phase, thus UCON-salt ATPS can be a suitable biphasic system for laccase extraction.     

Silver nanoplates and nanowires by a simple chemical reduction method

The critical micelle concentration (cmc) of an amphiphilic drug amitriptyline hydrochloride (AMT) was determined in the presence of varying amounts of inorganic salts (NaF, NaCl, NaBr, LiCl, KCl), urea and thiourea over the temperature range 293–308 K by conductometric and dye solubilization (ambient) techniques. The cmc values showed an inverted U-shaped behavior with temperature. In the presence of salts the cmc decreased which is explained on the basis of the nature and ion size. Urea and thiourea, at low concentrations (0.2 mM urea and 0.1 mM thiourea), decreased the cmc, whereas, at high concentrations, increase was observed with both the additives. Relevant thermodynamic parameters were also evaluated and discussed.     

Volumetric and viscosimetric properties of N-methyl-2-pyrrolidone with γ-butyrolactone and propylene carbonate

Volumetric properties of N-methyl-2-pyrrolidone (NMP) binary mixtures with γ-butyrolactone (GBL) and propylene carbonate (PC) are calculated from the experimental densities and reported in the temperature range from (293.15 to 323.15) K and at atmospheric pressure (0.1 MPa) over the whole composition range. The excess molar volumes have positive values in the whole concentration range in the case of (NMP + PC) binary mixture, with maximum value at equimolar composition, indicating weaker interactions between the components after the mixing. Two extreme V^E values are observed in (NMP + GBL) system: maximum at x(NMP) = 0.4 and minimum at x(NMP) = 0.9. Negative V^E values in NMP-rich region are the consequence of the better geometrical fit of the molecules. The excess properties of (NMP + GBL) and (NMP + PC) binaries are analyzed using Prigogine–Flory–Paterson theoretical model. An excellent agreement between experimental and theoretical values at equimolar composition is observed. Apparent molar volumes and thermal expansion coefficients are also calculated. Viscosity measurements of the pure components and NMP binary mixtures with GBL and PC were performed in the temperature range from (298.15 to 323.15) K. Using obtained experimental viscosities several semi-empirical equations and models were tested.     

Determination of tannic acid by adsorptive anodic stripping voltammetry at porous pseudo-carbon paste electrode

A novel and sensitive electrochemical sensor based on porous pseudo-carbon paste electrode (PPCPE) for tannic acid detection is described. PPCPE is fabricated by mixing calcium carbonate microspheres as the template, graphite powders as the filler, and pyrrole as the precursor of polymer which actually acted as the paste. After the polymerization of pyrrole catalyzed by Fe³⁺, the template calcium carbonate microspheres are removed with 0.1 M hydrochloric acid to form PPCPE. The diameters of these pores are in the range from 2 to 5 μm by SEM observations and the specific surface area of PPCPE is 59.26 m²/g by the Brunauer–Emmet–Teller (BET) method. A linear relationship between the anodic stripping peak current and the concentration of tannic acid from 0.02 to 1 μM and a limit of detection as low as 0.01 μM are obtained using PPCPE.     

New experimental heat capacity and enthalpy of formation of lithium cobalt oxide

The heat capacity of LiCoO₂ (O3-phase), constituent material in cathodes for lithium-ion batteries, was measured using two differential scanning calorimeters over the temperature range from (160 to 953) K (continuous method). As an alternative, the discontinuous method was employed over the temperature range from (493 to 693) K using a third calorimeter. Based on the results obtained, the enthalpy increment of LiCoO₂ was derived from T = 298.15 K up to 974.15 K. Very good agreement was obtained between the derived enthalpy increment and our independent measurements of enthalpy increment using transposed temperature drop calorimetry at 974.15 K. In addition, values of the enthalpy of formation of LiCoO₂ from the constituent oxides and elements were assessed based on measurements of enthalpy of dissolution using high temperature oxide melt drop solution calorimetry. The high temperature values obtained by these measurements are key input data in safety analysis and optimisation of the battery management systems which accounts for possible thermal runaway events.     

(Liquid + liquid) equilibrium of aqueous biphasic systems composed of 1-benzyl or 1-hexyl-3-methylimidazolium chloride ionic liquids and inorganic salts

(Liquid + liquid) equilibria for {1-benzyl-3-methylimidazolium chloride ([BzMIM]Cl) or 1-hexyl-3-methylimidazolium chloride ([HMIM]Cl) + inorganic salts (potassium phosphate K₃PO₄, potassium carbonate K₂CO₃, or dipotassium hydrogen phosphate K₂HPO₄) + H₂O} aqueous biphasic systems (ABSs) are presented at T = 298.15 K. An empirical equation was used to correlate the binodal data. The experimental tie lines were appropriately correlated by the Othmer–Tobias and Brancroft empirical equations. The influence of the selected inorganic salts in the phase segregation was investigated by means the calculated effective excluded volume (EEV) and Setschenow-type equation. The salting-out ability of salts was also evaluated in terms of the Gibbs energy of hydration of salt (ΔG_hyd) and assessed with EEV values.     

On the density and viscosity of (water + dimethylsulphoxide) binary mixtures

Density and viscosity of (water + dimethylsulphoxide) were measured precisely over the whole composition range at T = (298.15, 303.15, 308.15, 313.15, and 318.15) K. Differences between values from different authors are clarified and more reliable partial molar volumes are obtained.     

Apparent molar volumes and compressibilities of alkaline earth metal ions in methanol and dimethylsulfoxide

Temperature dependencies of density of magnesium (II), calcium (II), strontium (II), barium (II) perchlorates as well as beryllium (II), and sodium trifluoromethanesulfonates in methanol and dimethylsulfoxide have been determined over the composition range studied. From density data the apparent molar volumes and partial molar volumes of the salts at infinite dilution as well as the expansibilities have been evaluated. The apparent molar isentropic compressibilities of alkaline earth metal perchlorates and beryllium (II) and sodium triflates in methanol and DMSO have been calculated from sound speed data obtained at T = 298.15 K.     

Infrared studies of phase transitions in ferroelectric (C5H5NH)5Bi2Br11

Infrared spectra (3500–500 cm⁻¹) of polycrystalline (C₅H₅NH)₅Bi₂Br₁₁ samples were investigated within the temperature range 27–456 K. The assignments of the observed bands in the spectra measured at 27, 310 and 456 K are proposed. A temperature dependence of the wavenumbers and full width at half maximum (FWHM) of the bands arising from some internal vibrations of pyridinium cations are analysed in order to explain the role of cations in the mechanism of the phase transition at 118 (paraelectric–ferroelectric) and 403 K. It was found that numerous bands arising from the internal modes of the cations exhibit the splitting in the vicinity of both phase transitions, that indicates a distinct changes in the motional state of the pyridinium moieties.     

Density and sound speed study of hydration of 1-butyl-3-methylimidazolium based amino acid ionic liquids in aqueous solutions

Amino acid ionic liquids (AAILs) have huge potential in the field of protein chemistry, enzymatic reactions, templates for synthetic study etc. which is due to their distinctive properties like unique acid-base characteristics, tunable hydrophobicity, hydrogen bonding ability and strong hydration effects. To explore the field of bio-ionic liquids for its real life applications and sustainable technology development, it is essential to have better understanding of these newly researched liquid salts in life’s most chosen medium, i.e. in aqueous medium, through study of their physicochemical properties in aqueous solutions. In this context, we are reporting herewith measurements and analysis of volumetric properties in the temperature range of (293.15 to 313.25) K and acoustic properties at 298.15 K in the concentration range of (0.05 to 0.5) mol · kg⁻¹ for aqueous solutions of 1-butyl-3-methylimidazolium [Bmim] based amino acid ionic liquids, prepared from glycine, l-alanine, l-valine, l-leucine and l-isoleucine. The experimental density and sound speed data were used to obtain apparent, partial and limiting molar volumes as well as isentropic and isothermal compressibility properties. These data have been further used to understand electrostriction as well as concentration dependence of internal pressure. The hydration numbers for AAILs in aqueous medium were estimated from compressibility data using Passynski method and the estimated ionic hydration numbers are compared with those obtained using activity data. The results are explained in terms of cooperative hydration effects, hydrophobic interactions, kosmotropic behavior of AAILs, etc.     

Excess molar volumes of binary mixtures (an ionic liquid + water): A review

This review covers recent developments in the area of excess molar volumes for mixtures of {ILs (1) + H₂O (2)} where ILs refers to ionic liquids involving cations: imidazolium, pyridinium, pyrrolidinium, piperidinium, morpholinium and ammonium groups; and anions: tetraborate, triflate, hydrogensulphate, methylsulphate, ethylsulphate, thiocyanate, dicyanamide, octanate, acetate, nitrate, chloride, bromide, and iodine. The excess molar volumes of aqueous ILs were found to cover a wide range of values for the different ILs (ranging from −1.7 cm³ · mol⁻¹ to 1.2 cm³ · mol⁻¹). The excess molar volumes increased with increasing temperature for all systems studied in this review. The magnitude and in some cases the sign of the excess molar volumes for all the aqueous ILs mixtures, apart from the ammonium ILs, were very dependent on temperature. This was particularly important in the dilute IL concentration region. It was found that the sign and magnitude of the excess molar volumes of aqueous ILs (for ILs with hydrophobic cations), was more dependent on the nature of the anion than on the cation.     

Heat capacity (Cp) and entropy of olivine-type LiFePO4 in the temperature range (2 to 773) K

The heat capacity of olivine-type lithium iron phosphate (LiFePO₄ – LFP) has been measured covering a temperature range from (2 to 773) K. Three different calorimeters were used. The Physical Property Measurement System (PPMS) from Quantum Design was applied in the range between T = (2 and 300) K, a Micro-DSC II from Setaram within the range between T = (283 and 353) K and data between T = (278 and 773) K were measured by means of a Sensys DSC (Setaram) using the Cp-by-step method. Experimental data are given with an error of (1 to 2)% above T = 20 K and up to 8% below 20 K. The data were subdivided into appropriate temperature intervals and fitted using common heat capacity functions. The low temperature results permit the calculation of standard entropies and temperature coefficients of electronic, lattice, as well as magnetic (antiferromagnetic transition at T = 49.2 K) contributions to the heat capacity. The obtained experimental values were compared to results of a recently published first principles phonon study (DFT) and to few available experimental data from the literature.     

Separability of diastereomer salt pairs of 1-phenylethylamine with enantiomeric 2-substituted phenylacetic acids by fractional crystallization,and its relation to physical and phase properties

The separations of three pairs of the title diastereomer salts by crystallization have been investigated, as examples of the ‘classical’ resolution of enantiomers via conversion to diastereomers. All three fractional crystallizations occurred relatively slowly, and appeared to be thermodynamically controlled with the outcomes corresponding with the key features of the phase diagrams. In one case, X = CH₃, the salts–solvent ternaries exhibited eutonic behaviour, and the direction of isomeric enrichment changed markedly on passing through the eutonic composition. These salts also formed solid solutions on crystallization, but high separation factors were nevertheless recorded. In another example, X = OH, the ternaries indicated near-ideal solubility behaviour of the salt mixtures, and the separations by crystallization again corresponded. The stability and solubility ordering of the diastereomer pair X = CH₃ in the crystallization temperature range 5–50 °C were determined by the temperature-dependent entropic contribution to the free energy. Our results show that the use of simple surrogate parameters, such as the difference in the enthalpies of formation of the two salts, cannot be used as a reliable guide to their separability by crystallization. More rapid crystallizations are likely to be additionally influenced by kinetic factors, and their investigation is planned in future work.     

Enantioselective Michael reaction of β-keto esters organocatalyzed by recoverable Cinchona-derived dimeric ammonium salts

Dimeric anthracenyldimethyl-derived Cinchona ammonium salts are used as chiral organocatalysts in 1–10 mol % for the enantioselective conjugate addition of 2-alkoxycarbonyl-1-indanones to β-unsubstituted Michael acceptors. The corresponding adducts bearing a new all-carbon quaternary center were usually obtained in high yield and with up to 94% ee when using ammonium salts derived from quinidine and its pseudoenantiomer quinine as organocatalysts. These catalysts can be almost recovered quantitatively by precipitation in ether and reused.