Solubility Enthalpy Research Articles

Solubility, correlation, Hansen solubility parameter and thermodynamic analysis of 2,4-dinitroanisole in three binary mixed solvents

Melt cast explosive is the most widely used type of military explosives. Then 2,4-dinitroanisole (DNAN) is a liquid phase carrier of melt cast explosives, and it is the most promising substitute for TNT. In this study, the solubility of DNAN in three binary mixed solvents (MeOH + water, EtOH + water, i-PrOH + water) at the temperature range of 298.15 ∼ 333.15 K at atmospheric pressure (0.1 MPa) was measured by laser dynamic method. The experimental results show that the solubility of DNAN increase with increasing temperature and the fraction of the organic solvents. In order to expand the applicability of solubility, Apelblat equation, van't Hoff equation, λh equation and modified Jouyban-Acree model were used to correlate the solubility, and satisfactory results were obtained. The Apelblat equation have best correlation with the solubility data of DNAN. The solubility parameters of DNAN and binary mixed solvents were calculated through Hansen solubility parameter and Materials Studio. The solubility of DNAN in three binary mixed solvents show a regular pattern of i-PrOH + H2O > EtOH + H2O > MeOH + H2O. The above pattern is consistent with the solubility parameters prediction results and prove that the solubility data is true and effective. In addition, according to the experimental data, the standard solubility enthalpy ΔHdis° degree, standard entropy ΔSdis° degree, standard Gibbs free energy ΔGdis°, the enthalpy %ξH and the entropy %ξS were calculated and discussed.

Experimental solubility of aripiprazole in supercritical carbon dioxide and modeling

The solubility of compounds in supercritical carbon dioxide (SC-{mathrm{CO}}_{2}) has found crucial significance in the fabrication of micro/nano-scaled drugs. In this research, the solubility of Aripiprazole was measured in SC-{mathrm{CO}}_{2} at various temperatures (308–338 K) and pressures (12–30 MPa). Moreover, the experimental solubility results were correlated with several semi-empirical models (Chrastil, Bartle et al., Kumar & Johnston, Menden-Santiago & Teja, Sodeifian et al., and Jouyban et al.) as well as the modified Wilson model. The molar fraction of the drug in SC-{mathrm{CO}}_{2} varied in the range of 1.830times {10}^{-6} to 1.036times {10}^{-5}. The solubility highly depended on the operating pressure and temperature. The Chrastil (0.994), Jouyban et al. (0.993) and Sodeifian et al. (0.992) models showed the highest consistency with the obtained values. Furthermore, self-consistency tests were performed on the solubility of Aripiprazole in SC-{mathrm{CO}}_{2}. The approximate total enthalpy ({mathrm{Delta H}}_{mathrm{total}}), vaporization enthalpy ({mathrm{Delta H}}_{mathrm{vap}}), and solubility enthalpy ({mathrm{Delta H}}_{mathrm{sol}}) were also calculated.

On the size, shape and energetics of the hydration shell around alkanes.

A large number of clathrate-like cages have been proposed as the very first hydration shell of alkanes. The cages include canonical structures commonly found in clathrate hydrates and many others, not previously reported, derived from the carbon fullerene cavities. These structures have a rich and variegated form, which can adapt to the shape and conformation of the solute. They avoid "wasting" hydrogen bonds, while minimizing the volume cage and maximizing the solute-solvent van der Waals interactions. DFT/M06-2X and MP2 ab initio calculations give comparable structural and energetic results although the latter predicts slightly larger cages for a given solute. It is shown that the van der Waals interactions are substantial and the large exoenergetic values found for isobutane and cyclopentane provide an explanation for the surprising high melting points of related hydrates at room pressure. The encaging enthalpy for various hydrocarbons is similar to the enthalpy of solution measured at a temperature just above the melting point of aqueous hydrocarbon solutions, thus indicating that water molecules should not deviate too much from the configuration with O-H bonds tangentially oriented with respect to the solute surface. The computed trend differs from the enthalpy of solution measured at room temperature, thus the very first hydration shell departs, up to a certain degree, from the clathrate-like structures.

Phenanthrene adsorption on soils from the Yangtze River Delta region under different pH and temperature conditions.

The phenanthrene (PHE) adsorption on soils from the Yangtze River Delta region under different pH and temperature conditions was studied in the laboratory. Results showed that the sorption of PHE on all soils was nonlinear and fitted to the Freundlich isotherm. The PHE adsorption on the soils is related to the content of organic carbons and the environmental conditions. There was a positive correlation (the correlation coefficient was 0.956) between the PHE adsorption and the soil organic carbon content. Adsorption on the soils at 15°C ambient temperature was higher than at 25°C, which was related to PHE solubility enthalpy. Adsorption on the soils in background solution at pH 5.0 was higher than in those at pH 6.2 and 7.5, which may be related to alteration of the hydrophobic character of humic substances. This study showed that intrinsic organic carbons influenced the adsorption of PHE, which was affected by environmental conditions, such as pH and temperature. Therefore, the characteristics of soil organic carbon should be considered first for implementing effective schemes for the remediation of contaminated soils and in the formulation of soil environmental quality standards.

Energetics of cobalt alloys and compounds and solute–vacancy binding in fcc cobalt: A first-principles database

Using extensive first-principles density functional calculations, we calculate thermodynamic properties of binary fcc cobalt-based alloys with 25 different solute elements. For each solute element X, we calculate its (a) nearest- and next-nearest-neighbor solute–vacancy binding energy, (b) dilute impurity mixing energy with respect to the equilibrium and hypothetical fcc-based reference states of the solute, (c) enthalpy of formation of cobalt-rich binary ordered compounds in the Co–X system, (d) solubility enthalpy, and other derived quantities. We find that the solute–vacancy binding energies of all the studied solutes in fcc cobalt are positive (indicating favorable binding), in contrast to nickel, aluminum, magnesium, and copper-based alloys, where mid 3d transition metal solutes have unfavorable solute–vacancy binding. We study the physical and chemical effects influencing solute–vacancy binding energy, and find that (a) it correlates broadly with solute size—larger solute atoms possess stronger binding with vacancies—and this is understood in terms of strain relief and secondary next-nearest-neighbor interactions, and (b) it follows a parabolic trend as a function of d-occupancy across the transition metal series—falling to a minimum at the middle of the series—and this is understood in terms of a d-band filling effect. We also find this d-band filling effect in other calculated quantities such as the dilute impurity volumes and dilute impurity mixing energies. To aid in building thermodynamic databases, we tabulate all the calculated thermodynamic quantities, and compare them with experimental phase diagrams data and previous literature, and find good agreement where such data is available.

Evaluation of kinetic parameters for water soluble crystals by thermo gravimetric analysis

This work elevates the relevance of kinetic parameters of nucleation and thermal decomposition for water soluble crystals. The positive soluble Potassium Dihydrogen Phosphate (KDP) and negative soluble Lithium Sulfate Monohydrate (LSMH) materials were chosen for the kinetic evaluation. The results obtained from the classical nucleation theory are verified with the kinetic parameters which are evaluated from thermo gravimetric analysis. Nucleation parameters of a crystallization process such as interfacial energy (σ), volume free energy (ΔGv), critical energy barrier for nucleation (ΔG⁎), radius of the critical nucleus (r⁎) and nucleation rate (J) of the positive (KDP) and negative solubility (LSMH) crystals are determined from the classical nucleation theory of solubility–enthalpy relation. The kinetic parameters viz. the order of reaction, enthalpy, Gibbs free energy of activation, frequency factor, and entropy of activation are obtained from the TG based models viz. Horowitz–Metzger, Coats–Redfern and Piloyan–Novikova. The effect of varying temperature with relative variation on Gibbs free energy for both positive and negative solubility crystals is also discussed. The developed model holds good for both positive and negative solubility crystals.

Ab initio identified design principles of solid-solution strengthening in Al

Solid-solution strengthening in six Al–X binary systems is investigated using first-principle methods. The volumetric mismatch parameter and the solubility enthalpy per solute were calculated. We derive three rules for designing solid-solution strengthened alloys: (i) the solubility enthalpy per solute is related to the volumetric mismatch by a power law; (ii) for each annealing temperature, there exists an optimal solute–volume mismatch to achieve maximum strength; and (iii) the strengthening potential of high volumetric mismatch solutes is severely limited by their low solubility. Our results thus show that the thermodynamic properties of the system (here Al–X alloys) set clear upper bounds to the achievable strengthening effects owing to the reduced solubility with increasing volume mismatch.

Solubility of Lansoprazole in different solvents

By using a laser monitoring observation technique, the solubilities of Lansoprazole in ten pure solvents as well as in a binary solvent mixture (isopropyl alcohol) were measured in the temperature ranging from 283.15 to 318.15K. The experimental data were fitted using the modified Apelblat equation and two variants of the combined nearly ideal binary solvent/Redlich–Kister (CNIBS/R–K) model. The models were proven to give good representations of the experimental data. Computational results showed that variant 2 was superior to the variant 1 after comparison between the two variants of CNIBS/R–K model. The solubility enthalpy and entropy of Lansoprazole in all pure solvents and the mixed solvent system were calculated using van’t Hoff equation. The dissolving process was endothermic and entropy-driving.

Determination of thermodynamic parameters from light intensity signals obtained from oxygen optical sensors

A quite simple and inexpensive experimental set up using a platinum porphine/polysulfone-based oxygen optical sensor was used for determining thermodynamic parameters characterising polymers and luminophores constituting optical sensing membranes. In particular, the activation energies of the non-radiative, ΔEnr, and diffusion, ΔED, processes and the gas solubility enthalpy inside the polymeric layer, ΔEs, were computed. They were determined by expressing the Stern–Volmer constant, K′SV, in terms of luminophore life-time, diffusion coefficient and solubility of the analyte gas. The dependence of the three parameters on temperature ranging between 40 and 90°C was accounted for with suitable physical models used to obtain the cited parameters by regression procedures starting from experimental data. The found values are: ΔED=2.8(0.3)kJ/mol, and ΔEs=13(3)kJ/mol. These results are in agreement with literature data relative to similar layers. The experimental set-up of the sensor required the sensing membrane supported on optical fibers. Structural information about the membrane was also obtained by monitoring K′SV variations with time during the conditioning time, determining how long the polymeric structure takes for reaching equilibrium conditions.

Weak molecular associations investigated by 1H-NMR spectroscopy on a neat organosiloxane–solvent mixture

The rational design of new sensitive materials for chemical sensors relies on the knowledge of molecular interactions between the chemical species in question with compounds that may potentially be present in the gas phase. In this context, the intermolecular interactions between a family of functionalized polysiloxanes and a series of organic compounds have been investigated. This work addresses the problem of determining the association constant or energy by studying neat liquid mixtures without solvents. An original approach has been proposed to obtain such information from the excess function of the difference in chemical shifts between both interacting species. Data obtained as a function of the composition of the mixtures have been fitted according to two models: either by considering the formation of a 1:1 complex governed by an equilibrium constant or by the existence of a local composition following the Wilson model. Both methods have been tested on model compounds and the results have been compared with solubility enthalpies calculated using Hansen coefficients.

Dissolution kinetics of nanoscale liquid Pb/Bi inclusions at a grain boundary in aluminum

In situ transmission electron microscopy is used to study dissolution of liquid single-phase Pb/Bi inclusions attached to a grain boundary in an alloy of Al99.29Pb0.65Bi0.06 at temperatures of 343, 370, and 389 °C, respectively. The initial size of the inclusions was smaller than 60 nm. Dissolution of the inclusions was observed until their complete disappearance. Digitized video recordings of the process of dissolution were used to obtain the dependence of the inclusion size with time. The kinetics of the dissolution of the grain boundary inclusions can be described with a model where it is assumed that grain-boundary diffusion of Pb and Bi is the controlling mechanism. The high value (2.3 eV) of the apparent activation enthalpy of dissolution indicates that the process is likely governed by the large negative enthalpies of solubility of Pb and Bi in Al.

First-principles aluminum database: Energetics of binary Al alloys and compounds

Using an extensive series of first-principles density functional calculations, we have constructed a ``first-principles aluminum database'' of thermodynamic properties of binary Al-based alloys with 26 different solute elements, $X$. In all cases, first-principles results are critically compared to experimental data for observed Al-rich ordered compounds, dilute impurities in Al, disordered $\mathrm{Al}\text{\ensuremath{-}}X$ solid solutions, and pure elements, $X$, in a variety of structure types. We find the following: (i) In all $\mathrm{Al}\text{\ensuremath{-}}X$ systems, first-principles formation enthalpies of ordered compounds are in excellent agreement with experimental data. Impurity energetics for $X$ in Al also agree rather well with thermodynamically assessed values from the COST507 database. (ii) Formation enthalpies of ordered compounds and energies of dilute impurities for elements from the $3d$ series are most negative at the beginning and the end of the series, and reach a maximum near the middle of the series for Cr. The ordering tendency decreases dramatically in the Al-Cu system with filled $d$ bands. (iii) The special quasirandom structure approach has been used to obtain mixing energies of disordered solid solutions across the whole composition range for all systems. We find that mixing energies follow the same general trend across the $3d$ series as the ordered and impurity formation enthalpies. Asymmetry in the mixing energies is also similar in all systems, giving less negative mixing energies for Al-rich compositions. (iv) Calculation of the solubility enthalpy, which is the difference in the formation energy per solute atom between the ordered and dilute solid solution phases, shows that the observed low solubility in $\mathrm{Al}\text{\ensuremath{-}}X$ systems is due to very negative values of the ordered formation enthalpies in comparison with those for the dilute solid solution.

High-resolution measurements of water permeability and solubility in microelectronic-casing made of a hydrophobic polymeric composite

Exposing the composite polymeric casing of integrated circuits (ICs) to water results in miniscule water absorption, followed by its permeation throughout the packaging, and component damage. Studying water penetration and solubility mechanisms in the IC casing is crucial for understanding water-related damage mechanisms and protection against them. The main analytical challenge, hereafter, stems from the need to study miniscule water amounts (<0.5 wt %) capable of penetrating the casing, despite its hydrophobic nature. In this article, a TGA has been employed to study the water uptake kinetics in the casing, and to decipher the related water penetration mechanisms. High-resolution measurements of water adsorption and desorption profiles were performed, followed by calculations of the related activation energies and solubility enthalpies. These data were correlated with a relatively new model that assigned the primary locales of the adsorbed water to the compatible filler–polymer interface. Thus, water permeability is related to molecules hopping between these sites. Finally, we have shown that for the IC casing in our study, the activation energy of water permeation is related to the binding energy of H2O onto the SiOSi groups at the fused-silica-filler surface, where they desorb, hop, and reabsorb. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 4523–4527, 2006

The solubility of oxygen in Pd from its subsequent trapping of hydrogen

Solubilities of O in Pd have been measured by exposing Pd to O 2 (g) at elevated temperatures, 1073–1223 K, for sufficient times to obtain equilibrium. The amounts of dissolved O are determined from the extent of subsequent trapping of H by O (323 K). The solubility enthalpy is −49 ± 4 kJ/mol 1 2 O 2.

The Application of Ozone in Semiconductor Cleaning Processes: The Solubility Issue

The solubility of ozone in aqueous solutions expressed as a pseudo-Henry’s law coefficient for ozone, is measured over a pH range of 1 to 8, and temperature range of 15 to 45°C in the presence of several additives: HCl, HAc (Ac is acetate), NaAc, and NaOH. The value of was found to be a function of temperature, pH, and nature of the anion. The pseudo-Henry’s law coefficient is maximal at low pH and decreases with rising pH of the aqueous solution. The addition of chloride enhances the ozone decay rate and thus decreases the solubility below pH 2 while the addition of acetic acid/acetate results in an increase of for The solubility enthalpy for ozone is found to be equal to For applications of ozone in semiconductor cleaning processes, knowledge of the dependence of on pH, temperature, gas phase concentration, and additive is important in order to achieve optimized cleaning conditions. © 2001 The Electrochemical Society. All rights reserved.

Parametres thermodynamiques des defauts ponctuels dans le chlorure de strontium pur ou dope par des cations monovalents ou trivalents

The electrical conductivity of a great number of SrCl 2 crystals, either purified or doped with Na +, K +, Rb +, Gd 3+ and Ce 3+, has been studied. The microscopic models used for the interpretation of the results have been justified by dielectric loss measurements, ITC and EPR (for Gd 3+). The thermodynamic parameters of point defects have been derived, over the temperature range 420–860 K, from the fitting of experimental data to the equations of the Lidiard-Debye-Hückel theory. The values of the enthalpies of Cl vacancy mobility (0.30 eV) and Cl interstitial mobility (0.76eV), association of Cl vacancy with Na + (0.53 eV), K + (0.42 eV), Rb + (0.40 eV) and ionic Frenkel defects formation (2.20 ± 0.11 eV) have been used in the interpretation of the experimental results over a large concentration range. The solubility enthalpy of Na + is 1.2 ± 0.1 eV; the solubility of the rare earths is very small at low temperature. The thennodynamic parameters which have been found have been compared with other known experimental values and with theoretical results.

Doping of polyacetylene by diffusion of iodine

The solubility limit and diffusion coefficient of I 2 in (CH) x polymer have been measured with a radiotracer technique. The concentration of iodine in the polymer is a function of the surrounding concentration outside the film at equilibrium (free enthalpy of solubility = − 0.20 eV). The data are consistent with the following mechanism: liquid state diffusion of the solution in between the fibrils and solid state diffusion of iodine inside the fibrils. The macroscopic diffusion coefficient throughout the film is equal to 10 −9cm 2sec −1. These results restrict the present (CH) x polymer to heterolithic device applications after encapsulation. Monolithic substrate application will require a further inhibition of diffusion.

Temperature dependence of doping element incorporation with the chemical vapour deposition of epitaxial silicon (V). Incorporation of arsenic

AbstractBased on the knowledge previously obtained with regard to the incorporation of phosphorus as an equilibrium‐determined process, theoretical values of the enthalpies of the different possible incorporation equilibria are calculated for the incorporation of arsenic into the growing silicon epitaxial layer. The sublimation enthalpies of elemental arsenic, the formation enthalpy of arsine and the enthalpy of solubility enter into the equation. The results compared to the present experimental data of other authors are discussed.

Transport processes in NaCl single crystals doped with a trivalent cation; solubility, association and migration of Y 3+

The self-diffusion coefficient of 22Na + and the ionic conductivity are measured as a function of temperature in NaCl single crystals doped with labelled yttrium ions, as well as the diffusion coefficient of 88Y 3+. We give the theoretical equations for the transport processes in the alkali halides doped with a trivalent cation; These are derived from the theory of the crystals doped with divalent cations. Solubility of YCl 3 in NaCl is accurately determined through a radioactive technique. The free enthalpy of solubility of free Y 3+ is: (2.91−13 kT) eV. A good fit of the whole set of data is obtained by treating the association between Y 3+ ions and vacancies by the single equation K 2 = 12 exp (-9.5) exp ( 1.17 kT ) . The jump frequency of Y 3+ is w 2 = 1.37 × 10 13 exp (- 0.98 kT ) sec -1 . The results are compared to those characterising the divalent foreign cations.

Etude thermodynamique de la solution solide cuivresoufre

Sulphur solubility in copper single crystals was studied by means of H 2-H 2S mixtures and S 35 tracers, from 600 to 960°C. The copper-sulphur solid solution characteristics were determined: sulphur atoms are distributed at random, the solubility enthalpy is −7.5 kcal/mole, the excess partial entropy of sulphur in solid solution is high ( S ̄ s v/R = 12.7 ) and leads to suggest that sulphur atoms are substitution atoms. These results are consistent with some sulphur segregation in dislocations. Our results are in good agreement with our previous results about sulphur diffusion in copper.