Excess Refractive Index Research Articles

Thermophysical properties of binary mixtures of pentyl acetate with butanol at 298.15 K to 318.15 K: PFP theory, FTB model, and Graph theoretical approach

The measured density (ρ) and refractive index (nD) of binary pentyl acetate (1) + isomers of butanol (2) mixtures were reported at T = 298.15 K to 318.15 K and at 0.1 MPa pressure. Using the experimental ρ, u and nD data, excess molar volume (VmE), excess ultrasonic speed (uE), excess isentropic compressibility (κSE), and excess refractive index (nDE) were calculated and correlated with the Redlich–Kister (RK) equation. The findings suggest that the behavior of a mixture is affected by intermolecular interactions (cohesive forces such as dipole–dipole, H–bonding, dispersive force) and structural aspects of the molecules. The Prigogine–Flory–Patterson (PFP) theory, Flory–Treszczanowicz–Benson (FTB) model, and Graph theoretical approach (GTA) accurately analyzed the VmE values. Both the FTB model and PFP theory predicted the VmE curves not only successfully but also accurately represented their shape and magnitude except GTA at a lower mole fraction of pentyl acetate (xA<0.2). The positive values of VmE values were observed for binary mixtures across all temperatures. The intermolecular interactions were also corroborated by uE, κSE and nDE.

قياس ونمذجة الخواص الزائدة للمخاليط الثنائية والثلاثية من سيكلوهكسان و بيوتانول العادي 1-أوكتانول عند درجات حرارة مختلفة

This study aims to correlate the excess thermodynamic properties for new desirable mixtures. The density, refractive index, and viscosity of pure components and mixtures were measured over the entire composition range at atmospheric pressure and different temperatures. The results of measuring the density, viscosity, and refractive index were used to calculate the excess molar volumes, viscosity deviation, excess refractive index, and excess activation energies of viscous flow were reported for binary and ternary mixtures of cyclohexane, n-butanol, and 1-octanol at temperatures 20, 30, 40, and 50oC and over the whole mole fraction range. For all of the binary and ternary mixtures the computed excess molar volumes were correlated by applying the Redlich–Kister equation. and Prigogine–Flory–Patterson (PFP) theory. The correlations of excess molar volume, viscosity deviation, excess refractive index and excess activation energy to understand the effect of polar and nonpolar and temperature increase in the systems. Many works carried out to predict the excess thermodynamic properties, but the mixtures of this work have not been studied so far at such conditions. It is hoped that the present work will help in the availability of experimental data for some unknown mixtures to understand their behavior in the chemical processes, petrochemical industries and design processes. Keywords: Correlations, Excess properties, Density, Viscosity, cyclohexane and Alcohols, Binary and Ternary mixtures

The thermodynamic behavior of binary systems isoamyl acetate and alcohol through experimental measurements and modeling

The thermodynamic and transport properties are experimentally determined for three binary liquid mixtures consisting of isoamyl acetate and different alcohols at ambient pressure and in temperature range. From measured density, viscosity and refractive index are calculated excess molar volume, viscosity and refractive index deviations. Isentropic compressibility and excess molar Gibbs free energies of viscous flow are determined combining density with speed of sound and viscosity data. All mentioned derived properties are used to analyze the changes taking place in investigated binary systems causing deviations from the ideal mixture. Additionally, partial molar volumes and excess partial molar volumes, as well as thermal expansion coefficient, were calculated. The results are discussed in terms of chemical structure of used compounds and the influence of the alcohol present in the mixture on the mixture behavior. The study showed that higher influence has branching of the alcohol molecule and position of the –OH group rather than the length of the primary alcohol chain. Beside the experimental part, the modeling of the excess molar volume and viscosity was also performed, and the percentage deviations are used as the indicator of model performance in terms of model approach, predictive or correlative, and number of model parameters, one to three parameters optimized.

Densities, Excess Molar Volumes and Excess Refractive Indices for Binary Solutions of D2O and H2O

Densities, Excess Molar Volumes and Excess Refractive Indices for Binary Solutions of D2O and H2O

Thermophysical properties of ethyl levulinate and n-alkanol systems

Some thermophysical properties such as densities, speeds of sound, refractive indices, and heat flows of the binary systems ethyl levulinate and n-alkanols (methanol, ethanol, 1-propanol, and 1-butanol) are reported in the temperature range T = (283.15–313.15) K and at p = 100 kPa. From these experimental data, the excess properties were calculated and correlated with the composition using a modified Redlich–Kister equation. The excess molar volumes were negative for short-chain alcohols and positive for 1-propanol and 1-butanol. The excess refractive indices exhibited the opposite behaviour. The excess isentropic compressibilities were negative and the excess molar enthalpies, were positive. The perturbed chain statistical associating fluid theory equation of state (PC-SAFT EoS) was successfully applied to correlate the densities of the mixtures, and good qualitative results in the computation of the excess molar enthalpy were obtained. Furthermore, Schaaff’s collision factor theory (SCFT) and the Laplace mixing rule were coupled with PC-SAFT to predict the speed of sound and the refractive index, respectively.

Exploring molecular interactions in two aqueous alkanolamines mixtures using refractive indices and molecular probes

The optical and solvatochromic properties of aqueous mixtures of two alkanolamines (2-(ethylamino)ethanol and 2-(isopropylamino)ethanol) promising candidates to CO2 capture were investigated to better understand the changes in structural characteristics of the aggregation patterns formed throughout the whole composition range. The maximum absorption wavelengths of four molecular probes at T/K = 298.15, and refractive indices at T/K = (283.15 to 303.15) were measured. Solvent polarity descriptors (ETN30, ETN33, π*, α and β) and the corresponding mixing functions were derived. Molar refractions were calculated, and for the first time, excess molar refractions were estimated based on the recently derived refractive index of the ideal mixture. The correlation between excess refractive indices and excess molar volumes was explored, shedding light on the different ranges where changes in aggregation patterns are operating. Interesting insights on solvent polarity and structural details across the entire composition range were gained.

Thermodynamics of ternary mixtures of oxygenated fuel: Diisopropyl ether + ethanol + n-octane

Depleting conventional fossil fuels and growing greenhouse gases have fascinated the researcher’s heed for the use of green and clean fuels. Thereby, such fuels can be obtained by blending gasoline with the oxygenated fuel additives to reduce the toxic gaseous emissions and enhance the fuel efficiency in the motor engine. In this regard, various thermodynamic properties like densities (ρ), speeds of sound (u) and refractive indices (nD) of the ternary mixture of diisopropyl ether (1) + ethanol (2) + n-octane (3) were experimentally measured at different temperatures (298.15 K to 318.15 K) and at 0.1 MPa. The excess molar volume (VmE), deviation in sound speed (Δu), excess isentropic compressibility (κsE), excess available volume (VaE), excess free length (LfE) and refractive index deviation were evaluated using their corresponding experimental data. Different correlations and analytical rules have been used for conceptual assessment of speed of sound and refractive index of mixtures. The effect of temperature on the above stated thermodynamics properties has also been investigated.

Thermophysical Properties of Biodiesel with Ethyl Levulinate, Ethyl Acetoacetate, and Ethyl Pyruvate + MgO Mixtures from 288.15 to 338.15 K

Thermophysical properties are important to design the fuel system components and to evaluate new alternative fuels in diesel engine tests. Also, experimental properties allow us to understand the type of interactions present in the studied mixtures. Densities, viscosities, and refractive indices of biodiesel + ethyl levulinate, + ethyl acetoacetate, and + ethyl pyruvate with MgO mixtures have been measured from 288.15 to 338.15 K at 0.1 MPa over the whole composition range and at a constant concentration of 5 × 10–6 in mass fraction for MgO. Our experimental properties for the pure ketoesters agree with data reported in the literature within an average absolute percentage deviation of 0.056, 3.140, and 0.027 % for density, viscosity, and refractive index, respectively. Vibrating tube densimeter, glass capillary viscosimeter, and Abbemat refractometer have been used to measure the properties. Densities and viscosities of the biodiesel mixtures have been compared with the biodiesel fuel standard EN 14214. Flash point, cetane index, and calorific value of the biodiesel mixtures that meet the EN 14214 norm have been measured. Excess molar volume, viscosity deviation, and refractive index deviation are obtained from experimental data and correlated using the Redlich–Kister equation. Equations reported in the literature are used to correlate the thermophysical properties of the investigated mixtures.

Density, viscosity, refractive index and molecular interaction of polyethylene glycol 400 + 1,3-propanediamine deep eutectic solvent for CO2 capture

A new deep eutectic solvent (DES) was obtained using polyethylene glycol 400 (PEG400) as the H bond donor (HBD) and 1,3-propanediamine (PDA) as the H bond acceptor (HBA). Meanwhile, density(ρ), viscosity (η) and refractive index (nD) of (PEG400 + PDA) DES at T = (293.15 to 318.15) K with the step size of 5 K were measured under atmospheric pressure. Through the measured base data, excess molar volume (VmE), excess refractive index (nDE), viscosity deviation (Δη), deviation in molar refraction (ΔRM), refractive index deviation(ΔnD), excess Gibbs energy of activation of viscous flow (ΔG∗E), partial molar volume (V1¯ and V2¯), apparent molar volume (Vφ,1 and Vφ,2), molar isobaric thermal expansion (Ep,m) and thermal expansion coefficient (αρ), were systematically calculated and analyzed, and the Redlich-Kister (R-K) equation was used for fitting VmE, nDE, ΔRM, Δη, ΔnD, and ΔG∗E. In addition, several theoretical mixing rules related to refractive index were evaluated and compared with the experimental data. The results showed that there was a specific intermolecular hydrogen bonding interaction in (PEG400 + PDA) DES, which was systemically discussed on the basis of UV–vis, FLS, FTIR and Raman spectral technologies. At the molar fraction with the strongest intermolecular force, the maximum solubility of CO2 per 1 mol PDA was 0.99 mol CO2 at 150 mL/min CO2 flow rate.

Density, Viscosity, and Refractive Index of a Choline Chloride + d-(−)-Fructose Deep Eutectic Solvent + Water Mixture at Different Temperatures: An Experimental Study and Thermodynamic Modeling

In the present study, first, the deep eutectic solvent (DES) of choline chloride + d-(−)-fructose was prepared using the heating method. Then, its physical properties including density, viscosity, and refractive index were experimentally measured at temperatures in the range of 283.15–343.15 K and a full composition range of DES at atmospheric pressure (83.09 kPa). The values of these three properties decrease with an increase in temperature, while the mole fraction has a nonlinear effect on these properties. For the density and refractive index, an increase in the mole fraction of DES to 0.3 causes a sharp increase in these physical properties, while from 0.3 to 1, this increase occurs slowly. For viscosity, increasing the mole fraction of DES has little effect at first, but at high mole fractions of DES, a sharp increase in viscosity occurs. In addition, the sharp change in the viscosity of DES depends on the temperature so that at low temperatures, this phenomenon occurs faster. So, adding water to DES will tailor the viscosity of the mixture to facilitate its applications. A polynomial equation was used to describe the density and refractive index as a function of temperature and mole fraction. Experimental viscosity was fitted to the Vogel–Tammann–Fulcher (VTF) equation. Using the measured data, in sequence, the values of excess molar volume (VmEx), viscosity deviation (Δη), and refractive index deviation (ΔnD) were calculated. The Redlich–Kister polynomial equation, finally, was used to correlate the values of VmEx, Δη, and ΔnD.

Performance evaluation and prediction of activated carbon for VOCs via experiments and LFER methods

Due to the diversity and fluidity of volatile organic compounds (VOCs), it is difficult to conduct experimental studies on activated carbon (AC) used to capture VOCs in industry. Therefore, predicting the adsorption capacity of AC for VOCs is of great significance for evaluating the adsorption performance of AC and developing its promising applications. Herein, based on the experimental data of dynamic adsorption, the poly parameter linear free energy relationship (pp-LFER) model was developed to quantify the interactions between VOCs and AC. Through the dynamic adsorption curves of 25 VOCs on a fixed bed packed with the AC, the partition coefficient (PC) and adsorption capacity (q) of AC for VOCs were calculated, and the pp-LFER equations used to predict them were established. For the PC values, the pp-LFER model consists of the excess molar refractive index (E), molar polarizability (S), hydrogen-bond acidity (A), and logarithmic hexadecane-air partition coefficient (L), and the R2 of it was 0.86. For the ln q values, the developed model can predict it in R2 of 0.83, and the increased adsorption capacity was predominantly attributed to the dispersive interaction (lL). Finally, the internal and external validation results confirmed that the developed models have reliability, robustness, and predictability.

Static Dielectric Constants, Densities, Refractive Indices and Related Properties of Binary Mixtures at Various Temperatures Under Atmospheric Pressure

Experimental dielectric constants at (293.15, 298.15, 303.15) K, densities and refractive indices at 293.15 K are reported for water- ethanol and water- n-butanol binary mixture systems over the entire volume fraction range and atmospheric pressure. From the experimental dielectric data, the excess dielectric constant, effective Kirkwood correlation factor, Bruggeman factor and from density and refractive index data various parameters and their excess properties like excess density, excess refractive index, excess molar polarization, and excess molar volume were estimated and reported in the study. The static dielectric constant of the studied binary mixtures decreases with increase in temperature and volume fraction of the solutes. The density values are decreasing and refractive indices are increasing with increasing volume fraction of ethanol and n-butanol in water. Excess molar volumes values of ethanol and n-butanol are negative over the entire volume fraction range shows the presence of intermolecular interaction and hydrogen bonding in both the binary mixtures.

English

Refractive index is a characteristic parameter of fluids with numerous industrial uses. The values of refractive indices of many pure liquids are known or can be found in the literature. However, when experimental values of the liquid mixtures are not available then refractive indices of binary mixtures and multi-component liquids are frequently assessed from the pure constituents using mixing rules. The refractive indices &nbsp;of binary mixture and pure liquids methyl laurate (M.L) and pentan -2-ol (P) over the entire mole fraction range at five temperatures (298.15, 303.15, 308.15, 313.15, and 318.15K) were measured using an Anton-Paar Abbemat 3200 refractometer and were tested with the traditional equations, viz Gladstone-Dale (G.D), Lorentz-Lorentz (L.L), Weiner-relation (W.R) and Heller-relation (H.R). The excess refractive indices&nbsp;&nbsp;were calculated using measured experimental refractive indices&nbsp;&nbsp;and&nbsp; ideal refractive indices. The values of excess refractive indices were found to be negative at low mole fractions and positive over the high mole fractions. The experimental data for binary mixture involving methyl laurate + Pentan-2-ol authenticate the mixing rules. Key words: Excess refractive index, binary mixture, mixing rules, methyl laurate.

Thermophysical and excess properties of diesel + biodiesel with octanol isomers at different temperatures

Thermophysical properties of biodiesel mixtures are essential to design the injection system components and evaluate the spray characteristic through the combustion chamber as well as understand the type of interactions present in the mixture. In this work, densities, viscosities, and refractive indices of pseudo-ternary mixtures of diesel + biodiesel + 1-octanol, 2-octanol, and 2-ethyl-1-hexanol have been measured from (288.15 to 338.15) K at 0.1 MPa. In addition, properties of the pseudo-binary mixtures of biodiesel + octanol isomers are reported at the same temperature conditions and over the entire range of compositions. The experimental results for the pure components show agreement with data reported in literature within an average absolute percentage deviation of (0.019, 0.742, and 0.155) % for density, viscosity, and refractive index, respectively. Densities and viscosities of the mixtures have been compared with the limits set by the diesel fuel standard (EN 590). This work presents mixtures that meet these limits and can be considered as alternative fuels to conventional diesel. Excess molar volumes, viscosity deviations, and refractive index deviations are calculated from experimental data and represented through the Redlich-Kister equation. The McAllister and Nava-Ríos et al. equations have been used to correlate the kinematic viscosities of the pseudo binary and ternary mixtures as a function of the molar composition.

Excess Molar Volume, Viscosity and Refractive Index for Binary Mixtures of Methyl Laurate with n-Octane, Iso-Octane or Ethyl Cyclohexane

Excess Molar Volume, Viscosity and Refractive Index for Binary Mixtures of Methyl Laurate with n-Octane, Iso-Octane or Ethyl Cyclohexane

Study of short range and long range molecular interactions in binary liquid mixtures of N,N-dimethylformamide (DMF) and 1-propanol

In the present study precisely measured properties; static dielectric constant (ε0), refractive index (n) and density (ρ) of binary liquid mixtures of N,N-dimethylformamide (DMF) and 1-propanol (1-PN) have been used to determine linear correlation parameter (grr), mutual linear correlation parameter (gAB), excess Helmholtz free energy functions (ΔF) and excess molar polarization (ΔP). The dipolar contributions to these functions arising from long range electrostatic interaction, short range interaction between identical molecules and short range interaction between dissimilar molecules have been assessed separately. The excess thermodynamic functions calculated from the experimental data supports the formation of clusters with antiparallel or destructive angular correlation (β-clusters). The variation of excess static dielectric constant, excess refractive index and excess molar volume have been used to discuss the type, the strength and the nature of intermolecular interactions betweenconstituent species. Comparison of the predicted values of static dielectric constant and refractive index of the liquid mixtures using various mixing rules with the experimentally determined values have been assessed in terms of Average Percentage Deviation (APD).

Density, speed of sound, refractive index and relative permittivity of methanol, propan-1-ol or pentan-1-ol + benzylamine liquid mixtures. Application of the Kirkwood-Fröhlich model

Densities (ρ), speeds of sound (c), relative permittivities at 1 MHz (εr) and refractive indices at the sodium D-line (nD) at T = (293.15 K to 303.15 K) and p = 0.1 MPa are reported for binary liquid mixtures alkan-1-ol + benzylamine. Methanol, propan-1-ol and pentan-1-ol are the alkan-1-ols studied in this work. The values of the excess molar volume (VmE), excess isentropic compressibility (κSE), excess speed of sound (cE), excess refractive index (nDE), excess relative permittivity (εrE) and its temperature derivative (∂εrE/∂T)p are calculated, and they are adjusted to Redlich-Kister polynomials. The VmE values are negative, indicating a predominance of the solvation between unlike molecules and structural effects. εrE values indicate a positive contribution from the creation of (alkan-1-ol)-benzylamine interactions, and the positive value for the methanol mixture emphasises the importance of solvation. Calculations on excess molar refractions point out to weaker dispersive interactions than in the ideal mixture, which may be explained by the mentioned solvation effects. The Kirkwood-Fröhlich model has been applied to the mixtures, and the Kirkwood correlation factors suggest an important relative weight, especially in the methanol system, of linear-like molecules in the solutions, which is in accordance with the positive contribution of the formed multimers to εrE due to their good effective response to the electric field.

Probing the ion-dipole interactions between the imidazolium-based ionic liquids and polyethylene glycol 200 using excess thermodynamic and spectroscopy studies

The use of volatile organic compounds in industrial applications has generally been considered as detrimental to the environment and been a contributor to unsustainable activity. Ionic liquids (ILs) are generally considered as “green” and ecologically friendly solvents compared to volatile organic solvents. In the application of ILs in various processes, they are typically mixed with other solvents in order to modify their physicochemical properties. Thus, the focus in the present study on the interactions between ILs and polymer via thermophysical properties together with FT-IR analysis. In this study, density (ρ), viscosity (η), speeds of sound (u), and refractive index (nD) of the binary mixtures of 1-butyl-3-methylimidazolium hexafluorophosphate (BMIM+PF6-), 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIM+BF4-) and 1-butyl-3-methylimidazolium tetrafluoroborate (BMIM+BF4-) with polyethylene glycol 200 (PEG200) were measured at (293.15, 303.15, 313.15, 323.15 and 333.15) K and at p = 0.1 MPa. Excess thermodynamic properties: excess molar volume (VE), excess isentropic compressibility (KsE), excess viscosity (ηE), excess refractive index (nDE) and excess thermal expansion coefficient (αPE) were calculated from the thermophysical properties for the new systems studied. Excess thermodynamic properties were best correlated using the Redlich-Kister polynomial equation. Excess thermodynamic properties such as excess molar volume (VE), excess isentropic compressibility (KsE), and excess thermal expansion coefficient (αPE), displayed negative deviations, while excess viscosity (ηE) and excess refractive index (nDE) exhibited positive deviations throughout the entire composition range for the new systems. In addition, FT-IR spectroscopy was further utilized to confirm the presence of ion–dipole interactions/hydrogen bonding between the molecules of ILs and PEG200. The results from FT-IR spectra support the results obtained from excess thermodynamic properties. The results from both excess thermodynamic properties and FT-IR spectroscopy analysis confirmed the presence of ion–dipole interactions/hydrogen bonding. The strength of the ion–dipole interactions formed between molecules of PEG200 and ions of ILs follows the order: EMIM+BF4- >BMIM+PF6- > BMIM+BF4-. This study of the ILs + PEG200 binary mixtures contributes to the knowledge of physicochemical properties of these mixtures which can be utilized in specific applications such polymeric electrolytes in different electrochemical devices.

Densities, speeds of sound, refractive indices, excess and partial molar properties of polyethylene glycol 200 + benzyl methacrylate binary mixtures at temperatures from 293.15 to 318.15 K

Green and biodegradable solvents are requisite replacements to volatile organic solvents. Polyethylene glycols have been recognized as alternatives to volatile organic solvents in numerous industrial and pharmaceutical applications because of their unique properties. In this work the measurements of physicochemical properties, viz., densities, ρ, speeds of sound, u and refractive indices, nD of the binary mixtures of PEG 200 with benzyl methacrylate, including pure liquids, over the entire mole fraction range at the temperatures, T/K = 293.15 to 318.15 and at atmospheric pressure, p = 101 kPa. The experimental data were used to calculate the excess molar volume, VmE, excess isentropic compressibility, κsE, excess speed of sound, uE, excess acoustic impedance, ZE, excess molar isentropic compressibility, Ks,mE, excess refractive index, nDE and deviation in molar refraction, ΔRM . These excess properties were fitted with the Redlich-Kister polynomial equation. In addition, the partial molar volumes and partial molar compressibilities and excess partial molar volumes and excess partial molar compressibilities over the entire mole fraction range; and at infinite dilution were also calculated. The trends of these parameters with composition and temperature were discoursed from the point of view of intermolecular interactions existed in these mixtures.

Correlation between intermolecular interactions and excess properties of polyethylene glycol 400 + benzyl methacrylate binary mixtures at temperatures from 293.15 to 318.15 K

In the present study, the physicochemical properties such as the excess molar volumes, excess isentropic compressibilities, excess speeds of sound, excess molar compressibilities, excess refractive indices, and partial and excess partial molar volumes/compressibilities have been evaluated from the experimentally measured data of density, speed of sound and refractive index for the binary mixtures of polyethylene glycol 400 (PEG 400) with benzyl methacrylate over entire mole fraction range at the temperatures, T/K = (293.15–318.15) and pressure, p = 101 kPa. The partial molar volume/compressibility and excess partial molar volume/compressibility at infinite dilution have also been calculated. The correlations of the excess properties were made with the Redlich-Kister polynomial equation. The observed excess functions have been used to discuss the intermolecular interactions prevailing between the components in this system. Also, some theoretical mixing rules for correlating the refractive indexes were assessed and the results were compared with experimental data.