Vapor and sublimation pressures of organic and inorganic compounds : measurment and modeling

Depuis quelques années, nous assistons à une prise de conscience croissante des effets à long terme des polluants chimiques sur l'environnement et la santé humaine. Il est donc nécessaire d'étudier non seulement leurs propriétés écotoxicologiques mais également leurs propriétés physicochimiques tels que la tension de vapeur (ou volatilité) et leur solubilité dans l'eau. L'Europe, quant à elle, a introduit la réglementation REACH (Registration, Evaluation and Autorisation of CHemicals) qui est entrée en vigueur le 1 juin 2007 dont le principal objectif est une meilleure connaissance des propriétés environnementales et sanitaires des substances chimiques. De même dans l’industrie, la détermination de la tension de vapeur des corps purs est une donnée indispensable pour les opérations de purification et de séparation. Dans ce but nous avons amélioré un appareil à saturation de gaz inerte existant au laboratoire. Une fois le bon fonctionnement de l’appareil vérifié (par mesure de la tension de vapeur d’un composé de référence : le phénanthrène) nous avons étudié des n-alcanes compris entre le C30 et le C60 ainsi que 8 hydrocarbures aromatiques polycycliques dans un large domaine de température (20 à 320 °C) et de pression (10-1 Pa à 10-7 Pa). Les résultats obtenus ont été comparés avec la littérature lorsque celle-ci est disponible. La détermination des tensions de vapeur de composés inorganiques d’intérêt industriel : tétrachlorure de Zirconium (ZrCl4) et le tétrachlorure d’hafnium (HfCl4) a été également entreprise. Les résultats expérimentaux des hydrocarbures polyaromatiques nous ont permis l’amélioration d’une équation d’état cubique (dérivée de celle de Peng-Robinson) dont les paramètres sont estimés par une méthode de contribution de groupes développée par Rauzy-Coniglio. Les tensions de vapeur prédites par le modèle sont en bon accord avec les valeurs expérimentalesFor a few years, we have attended an increasing importance of the long-term effects of the chemical pollutants on the environment and human health. It is thus necessary to study not only their ecotoxicological properties but also their physico-chemical properties such as the vapor pressure (or volatility) and aqueous solubility. In Addition, the introduction of the regulation REACH (Registration, Evaluation and Authorization of CHemicals) in June 2007 whose main objective is a better knowledge of the environmental and medical properties of chemical substances has increased the necessity of compound characterization. From an industrial point of view, the determination of the vapor pressure of the pure substances is an essential data in many unit operations such as purification and separation. Thus, we improved an apparatus with saturation of inert gas existing at the laboratory. Once the good performance of the apparatus checked (by measurement of the vapor pressure of a reference compound: phenanthrene) we studied N-alkanes ranging between C30 and C60 and 8 polycyclic aromatic hydrocarbons in a broad temperature range (20 to 320°C) and of pressure (10-1 Pa with 10-7 Pa). The obtained results were compared with the literature when available. In addition, determination of the vapor pressure of inorganic compounds of industrial interest : zirconium tetrachloride (ZrCl4) and the hafnium tetrachloride (HfCl4) was also undertaken. The experimental results of polyaromatic hydrocarbons have allowed us to improve a cubic equation of state (derivative of Peng-Robinson EOS) whose parameters are estimated by a method of contribution of groups developed by Rauzy-Coniglio. The predicted vapor pressures were in good agreement with the experimental value

Salting-out phenomenon and 1-octanol/water partition coefficient of metalaxyl pesticide

International audienceIn this paper, we present the effect of inorganic cations such as Na(+), K(+), Ca(2+), Mg(2+) on the salting-out phenomenon of metalaxyl from pure water to aqueous salt solutions. Moreover the 1-octanol/water partition coefficient in pure water is presented. To accomplish this, aqueous solubility of metalaxyl was determined in pure water, in different salt solution (NaCl, KCl, CaCl(2) and MgCl(2)), and at different concentration level ranging from 0.01 to 1.5 M. The 1-octanol/water partition coefficient was determined using the static shake-flask method. Solubility was determined using dynamic saturation method for pure water in the range of 298.15-325.15 K and at 298.15 K for different salt solutions. The solubility value in pure water for studied interval was found constant (m = 3.118 x 10(-2) mol kg(-1)). Solubility values were used to calculate the standard molar Gibbs free energy of dissolution (Delta(sol)G degrees) and transfer (Delta(tr)G degrees) at 298.15 K. The values of A G from pure to all studied aqueous salt solutions did not exceed 2 kJ mol(-1), the value of of dissolution is 18.5 +/- 0.72 kJ mol(-1). The 1-octanol/water partition coefficient in pure water log K(o/w) is equal to 1.69. The obtained results confirm the classification of the neutral metalaxyl as a slightly hydrophobic molecule

Elimination of Tar in Biomass Gasification Process: Liquid–Liquid Equilibrium of Ternary Systems {Water + Solvent ( p -Xylene and Methyl Hexadecanoate) + Model Molecules of Tar (Thiophene, Pyridine, Naphthalene, Phenathrene, and Anthracene)}

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Mass transfer of non-polar heavy hydrocarbons in aqueous phase

International audienceLow aqueous solubilities are data of great importance in both industrial and environmental fields. As for the low aqueous solubility, we present the experimental apparatus along with the optimizations and adjustments (mechanical and analytical) applied to measure the solubility of heavy polyaromtics (solubility down to 10-9 in molal). The validation of our apparatus was achieved by measuring the aqueous solubility of the Fluoranthene in a range between 298.15 and 338.15 K. The quantification was done using GC-MS SIM with internal calibration method with benzo(a)pyrene as internal standard. Solubility of dibenz(a,c)anthracene was then explored between 298 and 333 K with an extremely low solubility of 10-12 in molar fraction

Vapor-Liquid Equilibria of Glycerol, 1,3-Propanediol, Glycerol plus Water, and Glycerol+1,3-Propanediol

International audienceVapor-liquid equilibria of two compounds, glycerol (or 1,2,3-propanetriol) and 1,3-propanediol, and two mixtures, glycerol + water and glycerol + 1,3-propanediol, were determined using a static apparatus. The obtained pressure values range from 6 Pa to 45 kPa for the compounds and from (32 to 163) kPa for the mixtures. From the temperature dependence of the vapor pressures, the molar enthalpies of vaporization at the mean temperature of the experimental range were derived from the Clausius-Clapeyron equation. From these results the standard enthalpies of vaporization at T = 298.15 K were calculated. The experimental data of the mixtures were correlated using the nonrandom two-liquid (NRTL) model

Liquid–Liquid Equilibria at Three Temperatures (between 280.15 K and 333.15 K) of Binary, Ternary, and Quaternary Systems Involving Monoethylene Glycol, Water, Cyclohexane, para -Xylene, trans - and cis -Dimethylcyclohexane, and trans - and cis -Decahydronaphthalene

International audienceNew solubility data for binary (ethylene glycol (or MEG) + cyclohexane or para-xylene), ternary (MEG/water + cyclohexane or para-xylene), and quaternary systems (MEG/water + trans- and cis-1,2-dimethylcyclohexane or trans- and cis-decahydronaphthalene (decalin)) under atmospheric pressure at three temperatures between 280.15 K and 333.15 K are reported. No literature data was available to compare with the present study. The consistency of the experimental data was checked through an Othmer–Tobias plot. The nonrandom two-liquid (NRTL) and the Soave–Redlich–Kwong modified (SRKM) thermodynamic models were used to correlate the experimental liquid–liquid equilibrium (LLE) data for all of the studied systems

Mass Transfer of Carbaryl from Pure Water to Salt Aqueous Solution: Result Comparison Between Sea and Lab-Made Water

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Prone versus Supine FDG PET/CT in the Staging of Breast Cancer

Supine [18F]Fluorodeoxyglucose (FDG) positron emission technology/computed tomography (PET/CT) is a commonly used modality for the initial staging of breast cancer, and several previous studies have shown superior sensitivity and specificity of prone FDG PET/CT in comparison to its supine counterpart. This retrospective study included 25 females with breast cancer referred for staging. They underwent supine FDG PET/CT followed by prone FDG PET/CT. The outcomes were: number of primary breast lesions, anatomical site of FDG-avid lymph nodes (LNs), and number and type of bone lesions, with SUVmax of all corresponding parameters. Performance was superior in prone acquisition compared to supine acquisition, with the respective results: 29 vs. 22 breast tumor lesions detected, 62 vs. 27 FDG-avid axillary LNs detected, sensitivity of 68% vs. 57%, specificity of 64% vs. 53%. The detection rate of axillary LNs in the prone position was significantly higher (p = 0.001). SUVmax for breast tumor lesions (p = 0.000) and number of detected axillary LNs (p = 0.002) were significantly higher in prone acquisition. Five patients were upstaged after experts read the prone acquisition. Prone FDG PET/CT acquisition is a promising technique in detecting primary breast lesions and metastatic LNs possibly missed in supine acquisition, which may lead to change in patient staging and management