Solubility and Dissolution Thermodynamics of Cefmetazole Acid in Four Neat Solvents and Preferential Solvation in Co-Solvent Mixtures of (Methanol,Ethanol or Isopropanol) + Water

The solubilities of cefmetazole acid in methanol, ethanol, isopropanol and water were determined experimentally by using the saturation shake-flask method within the temperature range from (278.15 to 303.15) K under pressure p?=?101.1 kPa. At a fixed temperature, the cefmetazole acid solubility falls in the order methanol?>?ethanol?>?isopropanol?>?water. The apparent dissolution enthalpy, dissolution entropy and Gibbs energy change were calculated. The acquired solubilities were correlated with Apelblat’s equation. The largest value of relative average deviation for mole fraction solubility was 0.45 × 10^?2, and of root-mean-square deviation, 0.747 × 10^?5. The type and extent and direction of solute–solvent interactions were identified using the concept of Linear Solvation Energy Relationship. In addition, the preferential solvation parameters (δx_1,3) of cefmetazole acid in co-solvent mixtures of methanol (1)?+?water (2), ethanol (1)?+?water (2) and isopropanol (1)?+?water (2) were derived via the inverse Kirkwood–Buff integrals method. At 298.15 K, the magnitude of preferential solvation of cefmetazole acid by the co-solvent is highest in methanol mixtures, followed by ethanol mixtures, and finally by isopropanol mixtures.     

Solubility of some phenolic compounds in aqueous alkali metal nitrate solutions from (293.15 to 318.15) K

This paper is continuation of the study concerning the solubility-temperature dependence data for some phenolic compounds (PhC), contained in olive mill wastewater (OMWW), in two nitrate salts (KNO₃ and NaNO₃) aqueous solutions. The solubilities of PhC were determined in the temperature ranging from (293.15 to 318.15) K. It has been observed that the solubility, in aqueous nitrate solutions, increases with increasing temperature. Results showed that alkali metal nitrate has a salting-out effect on the solubility of PhC. The effect of the anion of the electrolyte on the solubility of PhC is observed by comparing these results with values reported in the previous papers for the effect of LiCl, NaCl and KCl. For each cation, the solubilites of the phenolic compounds are higher with nitrate anion than with chloride anion. Results were interpreted in terms of the salt hydration shells and the ability of the solute to form hydrogen-bond with water. The solubility data were accurately correlated by a semi empirical equation. The standard molar Gibbs free energies of transfer of PhC (Δ_trG^°) from pure water to aqueous solutions of the nitrate salts have been calculated from the solubility data. The decrease in solubility is correlated to the positive Δ_trG^° value which is mainly of enthalpic origin.     

Solubilities of cinnamic acid esters in binary mixtures of ionic liquids and organic solvents

The solubilities of three cinnamic acid esters, namely, methyl ferulate, methyl p-coumarate, and methyl sinapate, have been measured in mixed solvent systems of tert-butanol with 1-butyl-3-methyl-imidazolium hexafluorophosphate ([BMIM][PF₆]), 1-butyl-3-methyl-imidazolium tetrafluoroborate ([BMIM][BF₄]) and 1-methyl-3-octyl-imidazolium tetrafluoroborate ([OMIM][BF₄]) at 303.15 and 321.15 K, and in mixed solvent systems of ethyl acetate with [BMIM][BF₄] and [OMIM][BF₄] at 303.15 K. In eight cases, out of the 22 data sets, an additive behaviour of the solubility was observed, positive deviations from additivity were observed in six cases, a positive synergistic effect in five cases, and, finally, negative deviations from additivity in the remaining three cases. Prediction of the solubilities of the solutes in the various ternary systems was performed with the NRTL and UNIQUAC activity coefficient models. The binary interaction parameters of the models between solute and solvent molecules were taken from the literature. When the parameters between the solvent molecules are fitted to literature data, satisfactory predictions are not always obtained. On the other hand, very good predictions are obtained when only one of the two interaction parameters between the two solvent molecules is fitted to one single point of the solubility isotherm and the other interaction parameter is set equal to zero.     

The temperature convergence of biopolymers in reversed-phase liquid chromatography

Summary Based on a stoichiometric displacement model for retention (SDM-R) in liquid chromatography, the two linear plots, log/(a constant relating to the affinity of one mole of solute to the stationary phase) andZ (the total moles of the displacing agent released at the interface between stationary phase and solute molecules as one mole of the solute is absorbed by the stationary phase) of small solutes and biopolymers versus the reciprocal of absolute temperature, l/T, in reversed-phase liquid chromatography were theoretically derived and experimentally proved to be linear and to have a common point called the temperature convergent point. The two linear plots could be used instead of the plot of logk to l/T which is normally only valid for small solutes but not for biopolymers for investigations of chromatographic thermodynamics and temperature convergence. The average convergence temperature (T _conv) of biopolymers was theoretically derived to equal the ratio between the slope and the intercept from either one of the two linear plots and to be 130.8±9.3°C for five proteins which are very close to those of biopolymers by calorimetry. A new methodology to investigate chromatographic thermodynamics and possibly for investigating the temperature convergence of biopolymers in the process of protein folding is also presented.     

Development of Abraham model correlations for describing the transfer of molecular solutes into propanenitrile and butanenitrile from water and from the gas phase

Experimental solubilities were measured for 20 crystalline organic solutes dissolved in propanenitrile and for 13 crystalline organic solutes dissolved in butanenitrile at 298.15 K. Infinite dilution activity coefficient data for solutes dissolved in propanenitrile and butanenitrile have been compiled from the published chemical and engineering literature and converted into gas-to-liquid partition coefficients and water-to-organic solvent partition coefficients through standard thermodynamic relationships. Abraham model correlations were developed for describing solute transfer into both propanenitrile and butanenitrile by combining our measured solubility data with the partition coefficients that we calculated from the published activity coefficient data. The derived Abraham model correlations were found to back-calculate the observed partition coefficients and molar solubility data to within 0.14 log units.     

Solubilities of Hexaphenoxycyclotriphosphazene and Tri(2-cyanoethyl)phosphine in Selected Solvents: Measurement and Correlation

Solubilities of hexaphenoxycyclotriphosphazene and tri(2-cyanoethyl)phosphine in selected solvents were measured in this work using a static analytical method. The solubilities of a series of phosphorus-containing flame retardants in organic solvents and water were recently measured in our laboratory. Based on these data and the solid?Cliquid equilibrium equation for the solute, the activity coefficients of these flame retardants were derived in pure solvents. The Scatchard?CHildebrand activity coefficient model was used to correlate these activity coefficients and the solubility parameters of the solutes were obtained. With the help of the analysis of the solubility parameters for the solute and solvents, solubility enhancement can be achieved due to the occurrence of the synergetic effect of the mixed solvent.     

Auswahl von Phasensystemen in der Lösungs-, Adsorptions- und Ionenaustausch-Chromatographie

In contrast to GC selectivity in LC is determined by the composition of both the stationary as well as the mobile phase. Therefore the main problem in LC results in selecting an appropriate phase system for the given separation problem. The selectivity factorα _ijis defined as the ratio of the capacity factors k′ _i k′_jof two solutes, which corresponds to the ratio of their distribution coefficients ^c K _i, ^cK_j. In LLC α _ijis determined by the relative solubility of the solutes in the two immiscible phases, which were prepared from binary or ternary liquid-liquid-systems. Secondary effects on retention are caused by the support. Two variations exist (LLC, Reverse-Phase-LLC) which differ in whether the polar phase is used as stationary or mobile phase, resp. In LSC the same phase variation is possible. Using a polar support and an unpolar solvent α _ijis governed by the relative strength of interactions between the solute molecules and the surface of the support. In Reverse-Phase-LSC, however, using an unpolar support and a polar solvent, these interactions are very weak and α _ijis mainly determined by the solubility of the solutes in the mobile phase. In IEC α _ijdepends on a set of parameters such as the type of ion-exchange matrix, its pore structure and its degree of crosslinking, resp., the type, surface concentration and distribution of functional groups, the type of the eluent ion, its concentration, the ionic strength and pH-value of the eluent, the temperature. Different methods have been developed in order to calculate the distribution coefficients of solutes for a given phase system.     

1‐Octanol/Water Partition Coefficients of 1Alkyl‐3‐methylimidazolium Chloride

The solubilities of 1alkyl‐3‐methylimidazolium chloride, [C_nmim][Cl], where n=4, 8, 10, and 12, in 1octanol and water have been measured by a dynamic method in the temperature range from 270 to 370 K. The solubility data was used to calculate the 1octanol/water partition coefficients as a function of temperature and alkyl substituent. The melting point, enthalpies of fusion, and enthalpies of solid–solid phase transitions were determined by differential scanning calorimetry, DSC. The solubility of [C_nmim][Cl], where n=10 or 12 in 1octanol is comparable and higher than that of [C₄mim][Cl] in 1octanol. Liquid 1n‐octyl‐3‐methylimidazolium chloride, [C₈mim][Cl], is not miscible with 1octanol and water, consequently, the liquid–liquid equilibrium, LLE was measured in this system. The differences between the solubilities in water for n=4 and 12 are shown only in α₁ and γ₁ solid crystalline phases. Additionally, the immiscibility region was observed for the higher concentration of [C₁₀mim][Cl] in water. The intermolecular solute–solvent interaction of 1butyl‐3‐methylimidazolium chloride with water is higher than for other 1alkyl‐3‐methylimidazolium chlorides. The data was correlated by means of the UNIQUAC ASM and two modified NRTL equations utilizing parameters derived from the solid–liquid equilibrium, SLE. The root‐mean‐square deviations of the solubility temperatures for all calculated data are from 1.8 to 7 K and depend on the particular equation used. In the calculations, the existence of two solid–solid first‐order phase transitions in [C₁₂mim][Cl] has also been taken into consideration. Experimental partition coefficients (log P) are negative at three temperatures; this is evidence for the possible use of these ionic liquids as green solvents.     

Modification of the Scaled Particle Theory for Solubility of Non-Polar Gases in Water

In this work based on the modified scaled particle theory (SPT), the solubility of non-polar gases (He, Ar, N₂, H₂, O₂, CO₂ and CH₄) in water has been studied over a wide range of temperatures. Calculations of Henry’s law constant by the SPT are related to the inherent physical properties and parameters of solvent and solute, all of which are considered temperature dependent. The temperature dependence of molar volume and hard sphere diameter of solvent and polarizability of solute have the most significant effects on the solubilities of gases in water. The average relative deviation is less than 3 %. Also, the effect of different mixing rules in the application of SPT to prediction of gas solubility has been studied.     

The influence of carbon dioxide cosolvent on solubility in poly(ethylene glycol)

Supercritical carbon dioxide (CO₂) and poly(ethylene glycol) (PEG) can be utilized as an environmentally friendly biphasic solvent system for catalysis reactions and subsequent product separation. To efficiently implement this technology, it is important to understand how solutes partition between these phases as well as how dissolved CO₂ in PEG affects the solvent properties. The work presented here explores the influence of CO₂ on the solubility of four different solutes in PEG. The transferable potentials for phase equilibria-united atom force field and configurational-bias Monte Carlo molecular simulation were employed to determine the solubilities of ethylbenzene, 1-octene, 1-pentanol, and 2-pentanone at 323.15 K and 15?MPa in PEG-600 using an ideal vapor phase with a Poynting-corrected vapor pressure. The effect of CO₂ concentration within the PEG phase was determined by varying the amount from no CO₂ to the saturation limit. The results indicate that while there is preferential solvation of CO₂ around the solutes, solubility of non-polar solutes is unchanged whereas there is a modest increase for polar solutes as the concentration of CO₂ increases. Increased solubility is analyzed in terms of both modified solvent structure and direct solute–CO₂ interactions.     

Effect of nonvolatile solute on vapor–liquid equilibrium at fixed liquid composition

The influence of some nonvolatile solutes on boiling points of two azeotropic mixtures (1-propanol–water and methanol–tetrahydrofuran systems) was determined by means of isobaric vapor–liquid equilibrium experiments. A basic thermodynamic equation of nonvolatile solute effect on vapor–liquid equilibrium at fixed liquid composition was derived. Based on the theoretical analysis about the equation, two criterions of universal significance were obtained: (1) when a little nonvolatile solute dissolves in a binary liquid mixture with constant composition, if the vapor composition of less volatile component is increased the boiling point must be elevated at given pressure or the vapor pressure must be depressed at given temperature; (2) when a little nonvolatile solute dissolves in an azeotropic mixture, any kind of nonvolatile solute always causes the elevation of boiling point at given pressure or the depression of vapor pressure at given temperature irrespective of the variation of vapor composition. Verifying through the experiments of this paper and lot of the relevant experimental data in the literature, all of the experimental results were in agreement with both criterions without exception.     

Solubility of HFCs in lower alcohols

This work is inserted in a research program that consists mainly in the experimental and theoretical study of the effect of association between solute and solvent molecules in the solubility of gases in liquids.The solubilities of hydrofluorocarbons, HFCs, (CH₃F, CH₂F₂, CHF₃) in lower alcohols (methanol, ethanol, 1-propanol, 1-butanol) have been determined in the temperature range [284, 313] K, at atmospheric pressure. An automated apparatus based on Ben-Naim-Baer and Tominaga et al. designs was used, which provides an accuracy of 0.6%. A precision of the same order of magnitude was achieved.To represent the temperature dependence of the mole fraction solubilities, the equation R ln x₂ = A + B/T + C ln T was used. From this equation, the experimental Gibbs energies, enthalpies and entropies of solution at 298 K and 1 atm partial pressure of the gas, were calculated.A semiempirical correlation has been developed between the solubilities of HFCs in alcohols at 298 K and the Gutmann acceptor number of solvents, AN, and reduced dipole moment of the gases, μ*.     

Effect of sugars on the solubility of hydrophobic solutes in water

It was found that the cosolvent effect of sugars on the solubilities of n-octanol, n-heptanol, and sodium dodecyl sulfate monomer in water depended on a set of factors that included molecular weight and concentration ofthe sugars, the kind of monosaccharides, the type of glycosidic linkages involved, and the temperature. All hexoses examined, D-glucose, D-galactose, and D-mannose, caused solubility depression of the hydrophobic solutes at low concentrations but to widely different extents. As the molecular weight of the sugar increased, the solubility depression was considerably lessened and further, as the concentration of the sugars increased, the solubility-increasing effect predominated leading to increased solubilities of the hydrophobic solutes relative of their solubility in pure water. The solubility-increasing effect was markedly enhanced at high temperatures. The free energy of the spontaneous transfer of octanol from water to the sugar solutions is entropic in nature and is attributed primarily to hydrophobic bond formation between the solute molecule and the hydrophobic surfaces of the sugar molecules.     

Solubility of gallic acid in liquid mixtures of (ethanol + water) from (293.15 to 318.15) K

The solubility of gallic acid in (water + ethanol) binary solvents was determined from (293.15 to 318.15) K at atmospheric pressure using a thermostatted reactor and UV/vis spectrophotometer analysis. The effects of binary solvents composition and temperature on the solubility were discussed. It was found that gallic acid solubility in (water + ethanol) mixed solvents presents a maximum-solubility effect. Two empirical equations were proposed to correlate the solubility data. The calculated solubilities show good agreement with the experimental data within the studied temperature range. Using the experimentally measured solubilities, the thermodynamic properties of dissolution of the gallic acid such as Gibbs energy (Δ_solG°), molar enthalpy of dissolution (Δ_solH°), and molar entropy of dissolution (Δ_solS°) were calculated.     

Solid–liquid equilibria for systems containing 1-butyl-3-methylimidazolium chloride

The solubility of 1-butyl-3-methylimidazolium chloride [C₄mim][Cl] in alcohols {ethanol, 1-butanol, 1-hexanol, 1-octanol, 1-decanol, 1-dodecanol, 2-butanol, 2-methyl-2-propanol (tert-butanol)} has been measured by a dynamic method from 270 K to the melting point of the ionic liquid or to the boiling point of the solvent. The melting point, enthalpy of fusion, and the temperature of the glass phase transition were determined by differential scanning calorimetry.The solubility data were correlated by means of the Wilson, UNIQUAC ASM and modified NRTL1 equations utilizing parameters derived from the solid–liquid equilibrium data. The root-mean-square deviations of the solubility temperatures for all calculated data were higher than 0.9 K and depended on the particular equation used.     

Room Temperature Ionic Liquids: Their Cohesive Energies,Solubility Parameters and Solubilities in Them

The cohesive energies of room temperature ionic liquids, RTILs, at the reference temperature T _ref = 298.15 K have been obtained from their molar enthalpies of vaporization. They are ce(298) = ?_v H°(298) ? 298.15R, on regarding the vapors as single ion-paired molecules. The cohesive energy densities, ced = ce/V = δ _H ² are the squares of the (Hildebrand) solubility parameters of the RTIL, which are presented for many RTILs. The solubilities of a variety of solutes in RTILs are discussed in relation to the solubility parameters. It turned out that the δ _H values of RTILs, obtained from the enthalpies of vaporization, may be used for empirical correlations, but are not able to predict the solubilities of solutes in RTILs.     

Radioxenon net count calculations revisited

To obtain the relationship between radon solubility and temperature, salinity, and pH of radon-bearing water in in situ leaching uranium mines, an experimental device for measuring the radon solubility in water was designed and manufactured. According to the range of temperature range, salinity, and pH of radon-containing radioactive water from in situ leaching mines in China, aqueous radon solubilities at different temperatures and salinities were determined using an orthogonal design and, concurrently, radon solubilities at different pH also determined. An empirical equation for estimating the radon solubility in radioactive water containing radon in uranium mining and metallurgy is proposed.

     

A new method for the determination of the unfrozen matrix concentration and the maximal freeze-concentration

During the freezing process, water is partially separated as ice and the solutes are concentrated in the unfrozen matrix (UFM). With further lowering of the temperature, the UFM becomes highly viscous. The high viscosity of the UFM prolongs ice formation and makes it difficult to accurately determine the glass transition (T_g′) and the concentration (C_g′) of the maximally freeze-concentrated matrix. In this study, a new method for the determination of the concentration of the UFM was developed using differential scanning calorimetry (DSC). Sugar solutions were frozen, annealed at temperatures slightly above the expected T_g′, rapidly cooled and then heated to 20 °C. The UFM concentrations of the annealed samples were obtained by estimating the solute concentration corresponding to the T_g at the respective annealing temperature. The dependence of the T_g on experimental conditions such as the annealing time, annealing temperature and cooling rate was studied in detail. Values for C_g′ and T_g′ were obtained by linear and quadratic extrapolations of the experimental data over a short temperature and solute concentration range. The maximal freeze-concentrations of glucose, sucrose and maltose were determined to be 79.9, 80.9 and 80.3% (w/w), respectively. Results of this study were in good agreement to previously published data.