Experimental Density Data Research Articles

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.

Decolourization of Disperse Blue 3 Dye by Electro coagulation process using Al and Fe electrodes –Application of the Artificial Neural Network Model

Contamination in wastewater is a major issue in the present world, the Disperse blue 3 dye (DB3) removal was studied by an electro coagulation process using Al and Fe electrodes. The experiments were performed with synthetic solutions in batch mode. The effect of the operating parameters like the electrolysis time, current density, initial pH, conductivity, inter-electrode distance and initial dye concentration, has been investigated. The results show high discoloration efficiency, reaching 98 and 96% with Al and Fe electrodes respectively. At the optimum condition of the EC process were electrolysis times of 70 and 30 min, current densities of 139 and 93 mA/cm², initial pH 5, conductivity of 5.67 mS/cm and inter-electrode distance of 1.5 cm. The Artificial Neural Network (ANN) technique was used to model the experimental data of the current density. The feed-forward neural network model was optimized by using the Levenberg-Marquardt algorithms. A comparison between the predicted and experimental data gave high correlation coefficients (0.99977 and 1) with the minimum MSE value (1.55.10-7 and 1.31.10-5) respectively for Al and Fe electrodes.

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.

Generalized Pitzer Correlation for Density Calculations of Ionic Liquids

The density of ionic liquids is an important design parameter for its utilization as a chemical process solvent. In this study, a generalized Pitzer-type correlation for calculating the density of ionic liquids with the use of reduced temperature (TR), reduced pressure (PR), and acentric factor (ω) as parameters is proposed. Experimental density data were obtained from several references through the IUPAC Ionic Liquids Database. Expansion of the terms as well as integrating the ionic liquid molecular weight was attempted to determine the accuracy improvement of the model in predicting densities at 0.1 MPa. Then, the obtained model was modified by further truncation to include the pressure effects for densities at higher pressures. MATLAB software was used to determine the optimal virial coefficients for the proposed correlations. The percent average absolute deviation (%AAD) was applied to calculate the variation between the experimental and calculated density values. It was concluded that the eight (8) coefficient correlation equation with molecular weight for densities at 0.1 MPa had a %AAD of 4.7537%. Upon modifying the correlation to include pressure effects, the resulting modified equation had an overall %AAD of 4.7174%.

Experimental and modeling of two heavy oil densities for temperatures from (288 to 358) K

Experimental liquid densities of two Omani heavy oils are provided as a function of temperature. The oils contain over 98% unknown fractions with molecular weights over 600. The unknown fractions were split using gamma function and characterized with methods suited for conventional oils. In addition, a previously developed saturated liquid density correlation was modified to calculate the liquid densities of the two heavy oils. A parameter so-called characteristic volume was developed to substitute critical volume. A method for estimating the characteristic volumes for unknown fractions is devised. A set of mixing rules is also furnished to apply with the modified density correlation. When the correlation with the mixing rules were applied to the heavy oils, the agreement with experimental liquid density data was found satisfactory. Average absolute deviation in calculating densities for both oils for temperatures from 288 K to 358 K was found to be 1.2%.

Two-band study on electromagnetic properties of Co-doped superconducting BaFe2As2 thin films

Identifying the form of the superconducting order parameter in the Co-doped BaFe2As2 thin film is still an unsolved problem. With the Neumann boundary condition, we study the electromagnetic properties of this thin film based on the two-band Ginzburg–Landau theory. We get the analytic expressions for the upper critical field in arbitrary direction and the temperature dependence of critical supercurrent density through the film. Our theoretical results can fit the experimental data of upper critical field and critical supercurrent density well, which thus strongly suggests the Co-doped BaFe2As2 thin film as a two-gap [Formula: see text]-wave superconductor. Besides, a trijunction experiment is proposed to probe the [Formula: see text]++ or [Formula: see text] pairing symmetry in this material.

Densities, viscosities and excess properties for n-nonane with alcohols (C3-C6) from 303.15 K to 333.15 K at atmospheric pressure

The volumetric and viscometric properties of the liquid mixtures are of importance for industrial application and theoretical calculation. This work reports the density and viscosity of the binary mixtures of n-nonane with 1-propanol, 1-butanol, 1-pentanol, and 1-hexanol from 303.15 K to 333.15 K at atmospheric pressure in the whole composition ranges. Excess properties such as excess molar volumes and viscosity deviations were calculated and correlated as the type of Redlich-Kister equation. In addition, the densities and viscosities for the studied mixtures were correlated using PC-SAFT equation and McAllister four-body viscosity model. For n-nonane with 1-propanol, 1-butanol, 1-pentanol, and 1-hexanol mixtures, the average absolute relative deviations between the experimental density data and calculate values from PC-SAFT equation are 0.39%, 0.46%, 0.31%, and 0.38%, respectively. And the average absolute relative deviations of viscosity from McAllister four-body model are 0.82%, 0.86%, 1.32%, and 1.01%, respectively.

Experimental data and modeling of liquid density, speed of sound, refractive index and derivative properties of ternary mixtures dibutyl ether + 1-butanol + heptane or + methylcyclohexane: Application of PC-SAFT equation of state

Thermophysical properties such as density, (ρ), speed of sound, (u), and refractive index, (nD), experimental data (549 points) are presented in this work at 0.1 MPa and 298.15 K for the following ternary mixtures: dibutyl ether (1) + 1-butanol (2) + heptane (3) and dibutyl ether (1) + 1-butanol (2) + methylcyclohexane (3) and their corresponding binary mixtures. In addition, derivative properties such as excess volume, (VE), deviations in speed of sound, (Δu), isentropic compressibility (ks), deviations in isentropic compressibility, (Δks), and deviations in refractive index, (ΔnD), were calculated from the presented measured data. The Redlich-Kister equation is used to correlate the calculated derivative properties. Therefore, the Perturbed-Chain Statistical Associating Fluid Theory (PC-SAFT) Equation of State (EoS) is used to model the reported experimental data of density, and a good agreement is noticed between the experimental and the modeled data of density for different studied binary and ternary mixtures.

Dynamic behaviour of a piled raft resting on saturated Kasai River sand

ABSTRACT The present work intends to calibrate the cyclic triaxial test and validate the 1-g shake table test of piled raft on saturated Kasai River sand. The outcome of the cyclic tests on Kasai river sand is already reported in the literature, but the present paper attempts to identify and explain the failure modes of the cyclic triaxial test as well as to numerically calibrate the experimental data(s) for relative density of 40% and 60%. For numerical validation and calibration, a bounding surface plasticity model is used. The calibrated parameters obtained from the element tests are used for validation of 1-g shake table test of piled raft resting on saturated sand. The numerical predictions are in good agreement with the experimental observations (in terms of acceleration, pore pressure). In addition, the effect of superstructure loading on piled raft is investigated in terms of variation of pore pressure (or effective stress) near and away from the structure and mechanism for vertical settlement of piled raft is identified. The relevant parameters related to seismic design of piled raft are identified and design guidelines in terms of strength and serviceability has been proposed.

Thermodynamic and spectroscopic properties of binary {1-Ethyl-3-methylimidazolium thiocyanate ([EMIM][SCN]) + alcohols} mixtures at T = (298.15 to 308.15) K and p = (0.1 to 40) MPa: Experimental study and modelling

In this study, densities for binary mixtures of {1-Ethyl-3-methylimidazolium thiocyanate ([EMIM][SCN]) + alcohols} have been measured at temperatures from T = (298.15 to 308.15) K and pressures from p = (0.1 to 40) MPa. These results have been used to calculate the excess molar volumes, partial molar volumes, apparent molar volumes and partial molar volumes at infinite dilution. The experimental density data were correlated by using the Tait-Tammann equation to obtain isothermal compressibility and isobaric expansion. Moreover, the values of excess molar volume were used to test the applicability of the Extended Real Associated Solution Model (ERAS Model). In order to elucidate possible structural phenomena, spectroscopic properties (H-NMR, C-NMR and FT-IR) were combined with the thermodynamic results trying to understand the molecular interactions among the unlike components present in the studied systems.

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.

A new approach for correlating of H2S solubility in [emim][Lac], [bmim][ac] and [emim][pro] ionic liquids using two-parts combined models

Two bi-part combined models containing reaction equilibrium thermodynamic model and an equation of state (EoS) including cubic plus association (CPA) or modified Soave-Redlich-Kwong (SRK), were employed to correlate H 2 S solubility in ionic liquids [emim][Lac], [bmim][Ac] and [emim][Pro]. RETM and CPA/mSRK are responsible for chemical and phase equilibria calculations, respectively. The RETM defines a complex formation reaction between an H 2 S and two IL molecules into the liquid phase so that a complex in the form of H 2 S(IL) 2 is probable to produce. On the other side, CPA/mSRK EoSs perform phase equilibria computations to find pressure and vapor phase concentrations. In the case of CPA, both of H 2 S and the ionic liquids were considered as self-associating components which pursue 4C and 2B schemes, respectively. This model computes the pure IL parameters using experimental density data. In this work, critical properties were estimated through the modified Lydersen-Joback-Reid method, Eotvos and Guggenheim relations. Afterward, the binary systems were investigated by applying RETM. CPA presents average absolute deviations (AADs) equal to 2.41%, 13.42% and 3.52% for [emim][Lac], [bmim][Ac], and [emim][Pro], respectively. Moreover, the AADs obtained by mSRK are 3.75%, 5.07%, and 6.06%, respectively. As it is evident from the results, the combination of RETM with both CPA and mSRK EoSs will result in good correlation accuracy.

Thermodynamic, transport, and structural properties of hydrophobic deep eutectic solvents composed of tetraalkylammonium chloride and decanoic acid.

With the emergence of hydrophobic deep eutectic solvents (DESs), the scope of applications of DESs has been expanded to include situations in which miscibility with water is undesirable. Whereas most studies have focused on the applications of hydrophobic DESs from a practical standpoint, few theoretical works exist that investigate the structural and thermodynamic properties at the nanoscale. In this study, Molecular Dynamics (MD) simulations have been performed to model DESs composed of tetraalkylammonium chloride hydrogen bond acceptor and decanoic acid hydrogen bond donor (HBD) at a molar ratio of 1:2, with three different cation chain lengths (4, 7, and 8). After fine-tuning force field parameters, densities, viscosities, self-diffusivities, and ionic conductivities of the DESs were computed over a wide temperature range. The liquid structure was examined using radial distribution functions (RDFs) and hydrogen bond analysis. The MD simulations reproduced the experimental density and viscosity data from the literature reasonably well and were used to predict diffusivities and ionic conductivities, for which experimental data are scarce or unavailable. It was found that although an increase in the cation chain length considerably affected the density and transport properties of the DESs (i.e., yielding smaller densities and slower dynamics), no significant influence was observed on the RDFs and the hydrogen bonds. The self-diffusivities showed the following order for the mobility of the various components: HBD > anion > cation. Strong hydrogen bonds between the hydroxyl and carbonyl groups of decanoic acid and between the hydroxyl group of decanoic acid and chloride were observed to dominate the intermolecular interactions.

Density and Electrical Conductivity for Aqueous Mixtures of Monoethylene Glycol and Sodium Chloride: Experimental Data and Data-Driven Modeling for Composition Determination

Monoethylene glycol (MEG) is a gas hydrate inhibitor widely applied for natural gas flow assurance. A series of density and electrical conductivity measurements of water + MEG + NaCl mixtures are reported, allowing the supervision of the MEG regeneration unit. Density (509 data points) and electrical conductivity (212 data points) measurements were performed in wide ranges of temperature, T = 278.15−363.15 K, and concentration of solvents and NaCl up to almost saturation. The theory of solutions was applied for density description using excess volume, which was correlated with the Redlich−Kister equation. The resulting absolute and relative mean deviations are 0.00127 g·cm−3 and 0.12%, indicating accurate representation. A semi- empirical correlation with 15 adjustable parameters was considered for electrical conductivity of water + MEG + NaCl mixtures. The obtained absolute and relative mean deviations are 1.49 mS·cm−1 and 5.70%. The properties functions presented an approximately orthogonal behavior to each other, allowing the determination of mixture composition from experimental density and electrical conductivity data. The Matlab environment was found to be robust in solving the nonlinear system of two equations with constraints. The proposed methodology was extensively tested, and deviations less than 0.0060 and 0.0011 in solvents and NaCl mass fractions were obtained, respectively, demonstrating the required accuracy for industrial application

Development of a robust soft-SAFT model for protic ionic liquids using new high-pressure density data

New experimental density data in a wide range of temperatures (283–363) K and pressures (0.1–95) MPa is here reported for five protic ILs based on the N,N-diethylethanolammonium ([DEEA]) cation, combined with the following anions: acetate ([Ace]), propanoate ([Prop]), butanoate ([But]), pentanoate ([Pent]) and hexanoate ([Hex]) in a 1:1 acid:base proportion. The molar volumes of the different ILs and derivative properties such as the isothermal compressibility and isobaric thermal expansivity were determined from the experimental density data. Moreover, considering the importance of having a robust and transferable thermodynamic model of these ILs that can be used in further studies including CO2 capture, the new experimental data was used to develop a coarse-grain molecular model of the studied ILs, in the framework of the soft-SAFT EoS, employing a 2/2 association scheme to account for the hydrogen bonding character of the ILs. The proposed model was found to provide an excellent description of the experimental pρT data with average relative deviations lower than 0.11% for all the ILs, while still providing reasonable predictions of the second-order derivative properties. Furthermore, the optimized molecular parameters were found to be correlated with the ILs molecular weight, highlighting the physical meaning and consistency of the parameters obtained.

Sintering of WC-Ni nanocomposite powder: Experimental and artificial neural networks modeling study

The sintering behavior of WC-Ni nanocomposite powder was evaluated through experimental and statistical approaches to study the contribution of involving parameters of chemical composition (Ni wt. %) and sintering temperature on sinterability of system by assessing the resulted densification and microhardness. The experimental process was designed based on factorial experimental design for independent effective parameters of Ni percentage (12, 18 and 23 wt %), and sintering temperature (8 different values within 1350–1485 °C). The resulted products of experimental testing after compaction and sintering were analyzed by FESEM and EDX to image the microstructure and evaluate the chemical composition and elemental distribution. The density and microhardness were measured as well. An artificial neural network (ANN) was applied to describe the corresponding individual and mutual impacts on sintering. The ANN model was developed by feed-forward back propagation network including topology 2:5:2 and trainlm algorithm to model and predict density and microhardness. A great agreement was observed between the predicted values by the ANN model and the experimental data for density and microhardness (regression coefficients (R2) of 0.9983 and 0.9924 for target functions of relative density and microhardness, respectively). Results showed that the relative importance of operating parameters on target functions (relative density and microhardness) was found to be 62% and 38% for sintering temperature and Ni percentage, respectively. Also, ANN model exhibited relatively high predictive ability and accuracy in describing nonlinear behavior of the sintering of WC-Ni nanocomposite powder. The experimental results confirmed that the appropriate sintering temperature was influenced by Ni content. The optimum parameters were found to be 12 wt % Ni sintered at 1460 °C with the highest microhardness and relative density.

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.

Volumetric and acoustic investigation of l-leucine and N-acetyl l-leucine in the aqueous solution of 1-hexyl-3-methylimidazolium bromide [HMIm] [br] at different temperatures

Present study reports density (ρ) and ultrasonic velocity (c) for l-leucine and N-acetyl l-leucine in (0.00, 0.005, 0.01, 0.03 and 0.05) mol.kg−1 aqueous solutions of 1-hexyl-3-methylimidazolium bromide [HMIm] [Br] at T = (288.15, 298.15, 308.15 and 318.15) K. Experimental data for density and ultrasonic velocity were used to calculate the apparent molar volumes (Vϕ), the apparent molar volumes at infinite dilution (Vϕ0), partial molar isentropic compression (Kϕ,s) and partial molar isentropic compression at infinite dilution (Kϕ,s0). Further pair and triplet interaction coefficients have been calculated from volumetric and acoustic studies. These Thermodynamic parameters are useful to study the solvation behaviour, structure making and different types of interactions present in the ternary solutions of (amino acids + water + [HMIm] [Br]).

Density and Viscosity of Aqueous (Ammonia + Carbon Dioxide) Solutions at Atmospheric Pressure and Temperatures between 278.15 and 318.15 K

The density and the viscosity of aqueous (NH3 + CO2) solutions have been measured at atmospheric pressure over a temperature range of 278 to 318 K and apparent concentrations of solute between 4 and 10 molNH3 kgH2O–1 for NH3 and between 1 and 5.2 molCO2 kgH2O–1 for CO2. Solute loss from the aqueous solution associated with the high equilibrium partial pressure of NH3 and of CO2 has been limited by devices and protocols developed ad-hoc for sample preparation and density and viscosity measurement. Solid or vapor formation out of the initial liquid mixture has been avoided by means of a thermodynamic model-driven design of experiments. The experimental values gathered in this work have been used to obtain empirical models of density and viscosity, as a function of the apparent concentration of solutes, that is, NH3 and CO2, and temperature, that are able to reproduce the experimental values in all cases with deviations below 1.1% for density and below 9.4% for viscosity. While it is the first time that, to our knowledge, experimental viscosity data of aqueous ammonia solutions loaded with CO2 are added to the literature, the density model developed in this work is also able to reproduce experimental density data from literature with deviations below 1.5%, even outside the boundaries of the experimental conditions considered in this work.

Effect of Selected Anionic and Cationic Drugs Affecting the Central Nervous System on Electrical Properties of Phosphatidylcholine Liposomes: Experiment and Theory.

Interactions between phospholipid membranes and selected drugs affecting the central nervous system (CNS) were investigated. Small, unilamellar liposomes were used as biomimetic cell membrane models. Microelectrophoretic experiments on two-component liposomes were performed using the electrophoretic light scattering technique (ELS). The effect of both positively (perphenazine, PF) and negatively (barbituric acid, BA) charged drugs on zwitterionic L-α-phosphatidylcholine (PC) membranes were analyzed. Experimental membrane surface charge density (δ) data were determined as a function of pH. Quantitative descriptions of the adsorption equilibria formed due to the binding of solution ions to analyzed two-component membranes are presented. Binding constants of the solution ions with perphenazine and barbituric acid-modified membranes were determined. The results of our research show that both charged drugs change surface charge density values of phosphatidylcholine membranes. It can be concluded that perphenazine and barbituric acid are located near the membrane surface, interacting electrostatically with phosphatidylcholine polar heads.