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Activity coefficient
About: Activity coefficient is a research topic. Over the lifetime, 6020 publications have been published within this topic receiving 132928 citations.
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TL;DR: In this paper , the authors analyzed the uncertainty sources that affect the measurements on VPO, establishing a general model for uncertainty, and applying this model to the particular case of a VPO prototype designed and constructed in this work as well.
Abstract: Vapor Pressure Osmometry (VPO) is a reliable technique for experimental measurement of both activity coefficient of solvents and molar weight of solutes. In this work were analyzed the uncertainty sources that affect the measurements on VPO, establishing a general model for uncertainty, and applying this model to the particular case of a VPO prototype designed and constructed in this work as well. In the analysis was included the effect of strong electrolyte solutes of different ratios on the uncertainty of the measurements.
In order to obtain a reliable mathematical model, a simplified thermodynamic model for the activity coefficient was used. Two types of electrolytes (1:1 and 1:2) were used for experimental runs in the diluted and non-diluted concentrations.
The osmometer was designed using thermistors, so, four commercial thermistors of two different types were calibrated in the range of 0-40°C according to ASTM E879 Standard, obtaining an expanded uncertainty of 0.014°C with a confidence level of 95%.
For the uncertainty budget, the relevant sources were identified and quantified. The expected uncertainty of the measurements ranged from 1.03x10-6 to 1.81x10-4 for the estimation of the activity coefficient with a confidence level of 95%.
TL;DR: In this article , the activity coefficients at infinite dilution (γ13∞) for organic solutes in deep eutectic solvent (DES) prepared by {1-butyl-2,3-dimethylimidazolium chloride (BDMIM Cl) + ethylene glycol (EG)} at a molar ratio of 1:3 have been measured using the gas-liquid chromatographic method (GLC).
Abstract: Activity coefficients at infinite dilution (γ13∞) for organic solutes in deep eutectic solvent (DES) prepared by {1-butyl-2,3-dimethylimidazolium chloride (BDMIM Cl) + ethylene glycol (EG)} at a molar ratio of 1:3 have been measured using the gas–liquid chromatographic method (GLC). The thermal stability of the entrainer was determined by the thermogravimetric analyzer. The measurements were carried out in the temperature range of T = (313.15 to 343.15) K and at atmospheric pressure. The values of the partial molar excess enthalpies at infinite dilution (H1E,∞) were derived from the temperature dependence of the γ13∞∞ values. The entropies (Tref ΔS1E,∞) and Gibbs energies (ΔG1E,∞) of organic solutes at a reference temperature Tref = 323.15 K were also calculated from the γ13∞ values. These excess thermodynamic functions were calculated to further explain the intermolecular interactions occurring between the volatile organic solvents and the prepared deep eutectic solvent. Important separation parameters such as selectivities (Sij∞) and capacities (Kj∞) at infinite dilution were computed from the activity coefficients at infinite dilution data at T = 313.15 K. Selectivity and capacity data were calculated for the industrial mixtures such as cyclohexane/benzene, hexane/thiophene, cyclohexane/ethanol. There results were compared to the literature data comprising deep eutectic solvents and ILs with the cation of 1-butyl-3-methylimidazolium. The investigated solvent was found suitable to separate azeotropes formed by alkanes/alcohols.
TL;DR: In this paper , the authors measured solid-liquid equilibrium diagrams of binary systems of potassium thiocyanate or potassium selenocyanates in {formamide or N-methylformamide, or N,Ndimethylformamide} as functions of temperature, using the cloud-point and DSC techniques over the full concentration range.
TL;DR: In this paper , the phase behavior of n-pentane + ethanol + α-tocopherol mixtures is investigated, and the authors use the Peng-Robinson equation of state combined with the MHV1 mixing rules and the predictive UNIFAC and COSMO-SAC dsp activity coefficient models to determine the vapor-liquid equilibria.