Experimental Vapor Pressure Data Research Articles

QSPR predicting the vapor pressure of pesticides into high/low volatility classes.

In this work, the vapor pressure of pesticides is employed as an indicator of their volatility potential. Quantitative Structure-Property Relationship models are established to predict the classification of compounds according to their volatility, into the high and low binary classes separated by the 1-mPa limit. A large dataset of 1005 structurally diverse pesticides with known experimental vapor pressure data at 20 °C is compiled from the publicly available Pesticide Properties DataBase (PPDB) and used for model development. The freely available PaDEL-Descriptor and ISIDA/Fragmentor molecular descriptor programs provide a large number of 19,947 non-conformational molecular descriptors that are analyzed through multivariable linear regressions and the Replacement Method technique. Through the selection of appropriate molecular descriptors of the substructure fragment type and the use of different standard classification metrics of model's quality, the classification of the structure-property relationship achieves acceptable results for discerning between the high and low volatility classes. Finally, an application of the obtained QSPR model is performed to predict the classes for 504 pesticides not having experimentally measured vapor pressures.

Application of Multiobjective Optimization in the Analysis of the Performance of Different Temperature Functions for a Generalized Cubic Equation of State

Since the emergence of van der Waals equation of state, several equations have been proposed to represent the behavior of pure compounds and mixtures, such as GEOS, which is a new generalized cubic equation of state form that employs a temperature function dependent on two or three adjustable parameters. Recently, multiobjective optimization has started to be applied in equations of state for parameters estimation, due to the conflicting nature of the objective functions. This methodology is attractive because it can be used to compare different models or variants of the same problem, through the trade-off analysis of the so-called Pareto front. In this context, the multiobjective PSO algorithm, based on the Pareto dominance principle, is used in this work for estimating the parameters of the generalized cubic equation of state, by fitting its results to synthetic experimental data of vapor pressure and saturated liquid volume. The performance of the new estimated parameters of the three temperature functions is investigated through the calculation of thermodynamic properties of interest in industry and academia. In addition, comparisons against real experimental data available in the literature are performed.

Thermochemistry of formation and phase transitions of substituted thiophenes at 298.15 K

This study presented experimental vapour pressure data and thermochemical properties of phase transitions for five substituted thiophenes. Using the transpiration technique, the temperature dependencies of vapour pressure and corresponding enthalpies of vaporisation were determined. Additionally, fusion enthalpies and melting temperatures for 3-acetylthiophene and 2,2′-di-thiophene were measured with differential scanning calorimetry. The solution enthalpies of the substituted thiophenes in benzene were used to evaluate the vaporisation and sublimation enthalpies at 298.15 K. The results of this study were found to be consistent with the literature data, allowing for reliable data on the vapour pressure and enthalpies of vaporisation and sublimation to be evaluated. Furthermore, the evaluated vaporisation and sublimation enthalpies were applied to validate the literature values of condense and gas state formation enthalpies for the studied substituted thiophenes. Additionally, quantum-chemical computations of the gas-phase enthalpies of formation were carried out.

Thermochemical properties of oxepane

In this work, the vapor pressures of oxepane (CAS 592-90-5) have been determined for the first time within the temperature range 276.2–303.2 K using the transpiration method. The enthalpy of vaporization of hexamethylene oxide was evaluated from the experimental vapor pressure data measured by using this method. Values of the enthalpies of combustion and formation have been determined for the first time by combustion calorimetry in a static bomb. A conformational analysis of oxepane in the gas has been performed using methods of molecular mechanics and ab initio computations; the structure of the most stable conformer has been identified. The enthalpy of formation of oxepane in the gaseous state was calculated with the composite G4 method. The thermodynamic functions of oxepane in the ideal gas state over wide temperature range (298.15–1500 K) have been evaluated. Values of the strain energies in a series of cyclic and heterocyclic compounds have been estimated.

Vapor-liquid equilibrium of acid gases with imidazolium-based ionic liquids using the UMR-PRU model

The UMR-PRU group contribution equation of state (EoS), which couples the Peng-Robinson EoS with UNIFAC via the Universal Mixing Rules, is extended to pure imidazolium-based ionic liquids (ILs), as well as to their mixtures with CO2 and H2S. The studied ILs consist of alkyl-methylimidazolium cations and tetrafluoroborate, hexafluorophosphate and bis(trifluoromethylsulfonyl)imide anions. The EoS parameters of pure ionic liquids, are determined by fitting experimental vapor pressure and liquid density data. For the extension of UMR-PRU to binary CO2/IL and H2S/IL mixtures, the model parameters are determined by fitting experimental binary vapor-liquid equilibrium data of acid gases with ionic liquids. For comparison, the Peng-Robinson coupled with the conventional van der Waals one-fluid mixing rules (vdW1f) is also applied to the same systems, using adjustable attractive and co-volume cross interaction parameter. It is shown that Peng-Robinson accurately describes pure ionic liquid vapor pressures and liquid densities, while UMR-PRU yields very satisfactory vapor-liquid equilibrium results for binary and ternary mixtures containing ILs and acid gases. Overall, UMR-PRU yields much better results than Peng-Robinson coupled with the vdW1f mixing rules, which indicates the superiority of the UMR mixing rules over the vdW1f ones.

Vapor pressure curves and isobaric vapor–liquid equilibrium for binary systems with compounds obtained from glycerol to be used as components of a bio-diesel mixture

The search of new renewable fuels and the interest of finding new uses for the abundant subproducts of many industrial processes have prompt Eni S.p.A to develop a technology for producing biofuels from glycerol. One of the compounds involved in this process is 2-ethyl-4-ethoxymethyl-1,3‑dioxolane (PrEDO). In this paper their temperature - vapor pressure curve has been determined experimentally as well as binary vapor–liquid equilibrium data at different pressures of systems where this compound is involved.The experimental vapor pressure data of PrEDO have been fitted with the Antoine equation. The vapor liquid equilibrium data have been correlated and calculated with UNIFAC, UNIQUAC, NRTL and Wilson to analyze their use when designing distillation processes.

Molecular Simulations of Vapor-Liquid Equilibrium of Isocyanates.

The wide range of applications of the isocyanates across multiple industries sparks the interest in the study of their phase behavior. A molecular simulation is a powerful tool that can go beyond experimental investigations relying on a molecular structure of a chemical. The success of a molecular simulation relies on a description of the system, namely, force field, and its parameterization on reproducing properties of interest. In this work, we propose a united-atom force field based on the transferable potentials for phase equilibria (TraPPE) to model the vapor-liquid phase behavior of isocyanates. With Monte Carlo and molecular dynamics simulation methods and the introduced force field, we modeled vapor-liquid equilibrium for a family of linear mono-isocyanates, from methyl isocyanate to hexyl isocyanate, and hexamethylene diisocyanate. Additionally, we performed similar calculations for methyl, ethyl, and butyl isocyanates based on the all-atom GAFF-IC force field available in the literature for modeling isocyanate viscosities. We showed that the developed TraPPE-based force field generally overperformed the GAFF-IC force field and overall showed excellent performance in modeling phase behavior of isocyanates. Based on the simulated vapor pressures for the considered compounds, we estimated the Antoine equation parameters to calculate the vapor pressure in a range of temperatures. The predictions are of particular use in the investigation of thermodynamic properties for those isocyanates lacking experimental vapor pressure data. Results can also be employed in modeling the phase behavior of isocyanate mixtures to investigate their sensing and capturing. Furthermore, from the vapor-liquid equilibrium binodals, we predicted the critical properties of isocyanates which can be used in thermodynamic models based on an equation of state.

Modeling of H2S absorption in some ionic liquids with carboxylate anions using modified HKM plus association EoS together with RETM

In current work, mHKM-CPA EoS together with the RETM was employed to correlate H2S absorption into five carboxylate ionic liquids, including 1-ethyl-3-methylimidazolium acetate ([emim][Ace]), 1-butyl-3-methylimidazolium acetate ([bmim][Ace]), 1-hexyl-3-methylimidazolium acetate ([hmim][Ace]), 1-ethyl-3-methylimidazolium lactate ([emim][Lac]) and 1-ethyl-3-methylimidazolium propionate ([emim][Pro]). The RETM proposes a chemical reaction between IL and H2S so that the liquid phase concentrations may be obtained by solving the model. Moreover, mHKM-CPA EoS contributes to VLE calculations. In the model, H2S considered as associating component with 4 association sites while the ILs assumed as non-self-associating compounds with one electron donor/acceptor sites.Fourteen adjustable variables of mHKM-CPA EoS for pure components were calculated using experimental liquid density and vapor pressure data. Afterward, binary systems were correlated by applying RETM. Indeed, two nested loops calculate the liquid phase, total pressure, and vapor phase concentrations, respectively.The parameters of the pure ILs were calculated with maximum AAD% below 0.3. Moreover, the binary results present 4.41 as the overall AAD% for 317 data points. Furthermore, a comparison between the results of the used model with those of the SRK-CPA was performed to show the capability of the mHKM-CPA EoS. As the outputs show, the model has a good ability to correlate the H2S solubility in the ILs concerning the classic SRK-CPA EoS.

Modeling the Vapor-Liquid equilibria of binary and ternary systems comprising associating and non-Associating compounds by using Perturbed-Chain Statistical association fluid Theory. Part I

Perturbed-Chain Statistical Associating Fluid Theory (PC-SAFT) was implemented for modeling the vapor–liquid equilibrium of binary and ternary systems of carbon dioxide (CO2) + fatty oil, CO2 + ionic liquids (IL), CO2 + perfluoroalkanes, CO2 + HFE-449mec-f, CO2 + water + IL, CO2 + thiophene, and alcohols + thiophene at temperatures between 298.15 and 543.15 K and at pressures up to 200 bar. ILs studied in this work contain 1-octyl-3-methylimidazolium hexafluorophosphate [OMIM][PF6] and N-methyl-2-hydroxyethylammonium propionate [m-2HEA][Pr]. The PC-SAFT pure-component parameters were fitted to the experimental density and vapor pressure data of pure-components. For ILs, only liquid density data were used to obtain pure-IL PC-SAFT parameters, because of the negligible values of the vapor pressure of ILs. Temperature-dependent binary interaction parameters of the binary and ternary systems were fitted to vapor–liquid equilibrium data taken from experimental literature data. These parameters were then used to describe the VLE of other binary and ternary systems. Correlation results of the PC-SAFT were found to be in qualitative agreement with the available experimental data and improved the modeling accuracy of past models in the literature. The overall value of the absolute average relative deviation in pressure (ARDP) and vapor-phase mole fraction (ARDy) of 12.05% and 6.13%, respectively, reveals the goodness of the developed models for modeling the phase behavior of other associating or non-associating mixtures with the same parameters reported in this work.

Thermodynamic Measurements and Correlation of Properties for Tribromomethane

Experimental saturated vapor pressure data were measured using a Modified Swietoslawski-type ebulliometer and correlated with the Antoine, Clarke–Glew, and Wagner equations. A least root-mean-square deviation (RMSD) was obtained for the Antoine (0.667) and Wagner (0.796) equations while the group contribution and group interaction (GCGI) method by Nanoolal et al. showed an RMSD of 1.094. The estimated enthalpy of vaporization is found to be 46.87 kJ·mol−1 and 38.56 kJ·mol−1 at reference temperature (298.15 K) and normal boiling point (422.28 K), respectively, and was well verified with Watson’s correlation. The critical properties and acentric factor are reported based on the GCGI method. Experimental density data are reported and are well correlated with the DIPPR 116 correlation with an RMSD of 0.00416. Joback’s method predicted the densities well with a maximum absolute deviation (MAD) of 0.00548. The Vogel–Tamman–Fulcher equation correlated the experimental viscosities in the temperature range of 288.15–338.15 K with a MAD of 0.002. The isothermal expansivity for tribromomethane shows a linear trend with a weak temperature dependency.

Simulation of H2S solubility in three acetate-based ionic liquids using PC-SAFT EoS together with RETM

In current work, Perturbed Chain- Statistical Associating Fluid Theory (PC-SAFT) EoS together with the Reaction Equilibrium Thermodynamic Model (RETM) was employed to correlate H2S solubility in three carboxylate ionic liquids including [emim][Ace], [bmim][Ace] and [hmim][Ace]. The RETM proposes a chemical reaction approach between IL (B) and H2S (A) in the liquid phase. Moreover PC-SAFT EoS contributes for VLE calculations. All the H2S and the investigated ILs, as self-associating components, assumed to follow 2B association scheme.Five adjustable variables of PC- SAFT EoS for pure components were calculated using experimental data of liquid density and vapor pressure. Afterwards, the binary systems were investigated applying RETM. Indeed, two nested loops calculate the liquid phase, total pressure and vapor phase concentrations, respectively. For these systems, AAD% equal to 2.29, 3.09 and 7.65 were obtained for all ILs respectively.

Vapour pressure and VLE data of fatty compounds

Knowledge of physical and thermodynamic properties of pure compounds and their mixtures enables the design and optimization of industrial processes. However, these experimental data obtained by conventional techniques might be uneconomical, especially because of the high cost of some pure chemicals and the requirement of large amount of reagents (50 mL–200 mL). Another difficulty of conventional techniques is in obtaining low vapour pressure data. The Differential Scanning Calorimetry (DSC) technique has been used as an alternative method to obtain vapour pressure and VLE data due to the advantages of a lower operating time. Therefore, the purpose of this work has been extending the methodology already used from saturated fatty compounds to unsaturated fatty compounds. However, improvements in the DSC technique were necessary to evaluate experimental vapour pressure data at low pressures (2.67–26.66 kPa) for this class of compounds, such as: linoleic acid and linoleic acid methyl ester and related mixtures. Experimental assays resulted in a maximum standard deviation of ± 0.86 K in relation to the saturation temperature. All analyses were performed in triplicate and the vapour pressure data have been modeled by the Antoine equation. The thermodynamic modelling of the experimental VLE data allowed the determination of binary interaction parameters for the UNIQUAC and NRTL models used to describe the non-ideality of the liquid phase.

Extremely Low Vapor-Pressure Data as Access to PC-SAFT Parameter Estimation for Ionic Liquids and Modeling of Precursor Solubility in Ionic Liquids.

Precursor solubility is a crucial factor in industrial applications, dominating the outcome of reactions and purification steps. The outcome and success of thermodynamic modelling of this industrially important property with equations of states, such as Perturbed‐Chain Statistical Associating Fluid Theory (PC‐SAFT), vastly depends on the quality of the pure‐component parameters. The pure‐component parameters for low‐volatile compounds such as ionic liquids (ILs) have been commonly estimated using mixture properties, e. g. the osmotic pressure of aqueous solutions. This leads to parameters that depend on the solvent, and transferability to other mixtures often causes poor modeling results. Mixture‐independent experimental properties would be a more suitable basis for the parameter estimation offering a way to universal parameter sets. Model parameters for ILs are available in the literature [10.1016/j.fluid.2012.05.029], but they were estimated using pure‐IL density data. The present work focuses on a step towards a more universal estimation strategy that includes new experimental vapor‐pressure data of the pure IL. ILs exhibit an almost negligible vapor pressure in magnitude of usually 10−5 Pa even at elevated temperatures. In this work, such vapor‐pressure data of a series of 1‐ethyl‐3‐methyl‐imidazolium‐based [C2mim]‐ILs with various IL‐anions (e. g. tetrafluoroborate [BF4]−, hexafluorophosphate [PF6]−, bis(trifluoromethylsulfonyl)imide [NTf2]−) were experimentally determined and subsequently used for PC‐SAFT parameter estimation. The so‐determined parameters were used to predict experimental molecular precursor solubility in ILs and infinitely diluted activity coefficients of various solvents in ILs. The parameters were further compared to modeling results using classical parametrization methods (use of liquid‐density data only for the molecular PC‐SAFT and the ion‐based electrolyte PC‐SAFT). As a result, the modeled precursor solubilities using the new approach are much more precise than using the classical parametrization methods, and required binary parameters were found to be much smaller (if needed). In sum, including the pure‐component vapor‐pressure data of ILs opens the door towards parameter estimation that is not biased by mixture data. This procedure might be suitable also for polymers and for all kind of ionic species but needs extension to ion‐specific parametrization in the long term.

Extractive distillation of the benzene and acetonitrile mixture using an ionic liquid as the entrainer

The benzene and acetonitrile azeotropic mixture was proposed to be separated by extractive distillation using an ionic liquid (IL) as the entrainer. The suitable IL was selected by the COSMO-RS model, and 1-ethyl-3-methylimidazolium tetrafluoroborate ([EMIM][BF4]) was considered as the suitable entrainer mainly due to its high selectivity, low viscosity, and low price. The experimental vapor pressure data of the IL-containing systems (benzene + [EMIM][BF4] and acetonitrile + [EMIM][BF4]) were measured in the full concentration range. The results show that acetonitrile has a stronger interaction with IL than benzene, and the low deviations between the experimental and UNIFAC predicted values show the reliability of the UNFIAC model. The UNIFAC predicted vapor–liquid equilibrium data of the benzene + acetonitrile + dimethyl sulfoxide (DMSO)/[EMIM][BF4] system show that the relative volatility of benzene to acetonitrile is higher when the entrainer is [EMIM][BF4]. The process simulation results show that [EMIM][BF4] can reduce the material and energy consumptions compared with DMSO.

Vapor Pressures of Phenolic Compounds Found in Pyrolysis Oil

Oil produced from pyrolysis of Kukersite oil shale and lignocellulosic biomass contains significant amounts of phenolic compounds. Here, we present new experimental vapor pressure data for two such...

A Comparative Study for Application of Pitzer and ePC-SAFT Equations to Predict Volumetric and Saturation Properties in “Formation” Water

Predictions of salt solubility, brine vapor pressure and density are necessary to plan subsurface and surface operations. In this work, a comparative study was conducted to investigate prediction capabilities for salt solubility, equilibrium and volumetric properties of several minerals in “Formation” water by the Pitzer model (a commonly used industrial model) and by the ePC-SAFT equation of state (EOS). To achieve this, several validation and comparison steps were considered for reliable implementation of both models. Firstly, solubility, brine densities and vapor pressures for single-salt solutions were predicted. Afterward, the models’ applications were extended to several mixtures of two salts to predict solubility compared to experimental data from available literature. ePC-SAFT shows promising accuracy. The average relative deviation for prediction of liquid density (which cannot be estimated with the Pitzer model) for single-salt solutions of NaBr, KCl, NaCl and Na2SO4 are 1.13%, 0.70%, 1.02% and 0.36%, respectively. The average relative deviation from experimental data of vapor pressure for mixtures of NaCl and KBr is 0.75% and for mixtures of NaBr and KCl is 0.74% for systems with different concentrations. Moreover, a stochastic regression procedure is presented to evaluate the ePC-SAFT parameters. This technique is used for strontium in different salt solutions. The average relative deviation for mean ionic activity coefficients calculated by ePC-SAFT from experimental data using the ePC-SAFT parameters of strontium from the work of Held et al. [1] for single-salt solutions of strontium chloride, strontium bromide, strontium iodide, strontium nitrate and strontium perchlorate are 19.73%, 19.96%, 15.15%, 14.95% and 25.70%, respectively. These values using the ePC-SAFT parameters of strontium regressed in this work are 6.98%, 10.13%, 8.33%, 9.59% and 10.08%, respectively. Finally, the solubility of different salts was studied for mixing of formation water (FW) and injection water (SW).

Modelling the thermodynamic properties and fluid-phase equilibria of n-perfluoroalkanes and their binary mixtures with the SAFT-γ Mie group contribution equation of state

The SAFT-γ Mie group-contribution approach is extended to describe the thermodynamic properties and fluid-phase behaviour of n-perfluoroalkanes and their binary mixtures. New molecular interaction parameters characterising the functional chemical groups forming these molecules (CF4, CF3 and CF2) are estimated from experimental vapour pressure and saturated-density data of the pure compounds. The vapour–liquid equilibria of four mixtures are then described predictively and compared to recent experimental data from the literature. Additionally, new experimental data for the excess volume of the (n-C6F14 + n-C8F18) mixture is measured over the whole range of compositions, between 278.15 and 318.15 K. The mixture presents small negative excess volumes, which increase in absolute value with increasing temperature. The results are compared with the excess volume for the corresponding mixture of n-alkanes of the same chain length, and with the SAFT-γ Mie predictions. The theory provides a very good description of the properties of both the pure compounds and their binary mixtures.

Modeling the solubility of Alkyl Ketene Dimer in supercritical carbon dioxide: Peng-Robinson, group contribution methods, and effect of critical density on solubility predictions

Alkyl Ketene Dimer (AKD) is a sizing agent commonly introduced into cellulose substrates during papermaking to improve its hydrophobicity. High-pressure impregnation of this solute with supercritical carbon dioxide (scCO2) into cellulose and other substrates can achieve excellent hydrophobicity of the substrate, and may be used as an alternative technique to traditional coating (sizing) methods. In this study, the solubility of AKD in scCO2 was modelled using Peng-Robinson equation of state (PR-EOS) with van der Waals mixing rules, and volume-translated PR-EOS (VTPR). Given the unavailability of AKD's experimental critical properties and vapor pressure data, group contribution estimation methods (GCEM) were used to determine these physical constants. Available experimental data from another research group, collected using cloud-point and extraction methods, was used to regress binary interaction parameters and compare the resulting model's capability in predicting solubility. The models for each experimental method predicted crossover pressures within a small range, but fitted the cloud-point experimental data much better than the extraction data, showing good agreement at pressures beyond 15 MPa and all temperatures investigated. The VTPR model showed the least agreement with experimental data. A relative standard deviation of 0.26 was obtained between modelled and experimental data for the cloud-point method, and 0.42 for the extraction method data. The models were confirmed with the Chrastil equation, and strongly demonstrated the linear relationships predicted by this expression. The models additionally predicted a change in temperature dependence around the critical density, with a common linear relationship independent of temperature being observed at densities below the critical value. This newly observed behavior, not predicted by the Chrastil equation, sets the groundwork for further fundamental investigations, while the developed models will assist the design of alternative sizing processes involving AKD and scCO2.

Isobaric Vapor Liquid Equilibrium Data for the 1,2-Dichloroethane–1-Butanol System

Boiling points for 1,2-dichloroethane and 1-butanol were determined, and P–T–x data for the binary mixture were measured under isobaric conditions using a modified ebulliometer in the pressure range of (101.325 to 60.0) kPa. The pure component experimental vapor pressure data were modeled using Antoine, Wagner, and Thomas models and compared with the literature values. The modeling of binary VLE data was done using Margules 3-suffix, Wilson, and NRTL models. The average RMSD(T) values based on the literature and model predictions for the pure components are in the ranges of (0.42 to 0.47) K and (0.03 to 0.08) K, respectively. Similarly, for the binary system the average RMSD(T) value based on the model prediction is 0.33 K.

A five-parameter cubic equation of state for pure fluids and mixtures

A five parameter cubic equation of state, named 5PGDN is presented for the prediction of thermodynamic properties of pure fluids and mixtures. A new alpha function is proposed with two compound specific parameters which are estimated by matching experimental saturation vapor pressure data at two fixed temperatures Tr=0.5,0.7. We have cast three of the five parameters in terms of the remaining two parameters. The 5PGDN uses the critical temperature, the critical pressure, the critical compressibility factor, and two parameters of the alpha function to calculate thermodynamic properties such as saturated vapor pressure, liquid and vapor density, enthalpy of vaporization, sound velocity, heat capacity at constant pressure and volume. The 5PGDN is further used for the prediction of bubble point pressure and vapor mole fraction of several binary mixtures. The accuracy of 5PGDN is demonstrated by comparing results with the Patel-Teja (PT), Haghtalab-Kamali-Mazloumi-Mahmoodi (HKM1) and Ghoderao-Dalvi-Narayan (4PGDN1) equations of state.