Osmotic Coefficient Data Research Articles

A conventional, molal-based Pitzer model for the (H+ – Nd3+ – NO3−){aq} system valid to stoichiometric ionic strengths near 40 mol·kg−1 at 298 K and 0.1 MPa

Existing molal-based Pitzer activity coefficient models for (H + Nd + NO3){aq} mixtures are either inaccurate, ill-formed, or do not span the ionic strength (I) range of the solid solubility data for the (H + Nd + ox + NO3){aq} system. As a precedential step in developing a thermodynamic model for aqueous neodymium-oxalate-bearing systems, a speciated, conventional Pitzer model was fitted to the osmotic coefficient and solid solubility data for the (H + Nd + NO3){aq} system at 298 K and 0.1 MPa. The presented HNO3{aq} model spans the range, 0 < I < 30 mol·kg−1, using fewer parameters than previously published molal-based conventional Pitzer models for the speciated system. The Nd(NO3)3{aq} and novel (H + Nd + NO3){aq} models reproduce the fitted isopiestic and solid solubility data within their accuracy between infinite dilution and stoichiometric ionic strengths up to ∼40 mol·kg−1.

Thermodynamic models for solution behavior and solid-liquid equilibrium in acetate binary systems from low to very high concentration at 25oC

In this study we developed new thermodynamic models for solution behavior and solid-liquid equilibrium in eight acetate binary systems from low to very high concentration at 25oC: six systems of the type 1-1 (X(CH3COO)-H2O with X= (Li, Na, K, Rb, Cs, and Tl)) and two systems of the type 2-1 (Y(CH3COO)2-H2O with Y= (Mg, and Ba)). Models were developed on the basis of Pitzer ion interactions approach. To parameterize models for binary systems we used all available experimental osmotic coefficients data (φ) for the whole concentration range of solutions. To develop models, we used different versions of the standard molality-based Pitzer approach. It was established that for all acetate systems under study application of extended approach with 4 parameters (β0 , β1 , β2 and Cφ ) and variation of 1 and 2 terms in fundamental Pitzer equations leads to the lowest values of standard model-experiment deviation. The predictions of new developed here models are in excellent agreement with experimental φ data, and with recommendations on the mean activity coefficients (±) from low to very high concentration: up to 23.8 m in K(CH3COO)-H2O, up to 39.2 m in Rb(CH3COO)-H2O, and up to 52.2 m in Cs(CH3COO)-H2O. On the basis of evaluated binary parameters important thermodynamic characteristics (Deliquescence Relative Humidity DRH, thermodynamic solubility products Ko sp; standard molar Gibbs free energy of formation, fGo m) for 7 acetate solids were determined at 25oC. The calculated DRH and fGo m values were compared with those reported in the literature. The models described in this study are of high importance, especially in development and improvement of technology for production and purification of acetate solutions and solid phases.

Osmotic Coefficients of Gabapentin Drug in Aqueous Solutions of Deep Eutectic Solvents: Experimental Measurements and Thermodynamic Modeling

Most of the applications for aqueous deep eutectic solvent (DES) solutions are directly related to molecular interactions, which can be studied using thermodynamic properties. In this regard, the activity coefficient and osmotic coefficient studies have provided evidence for understanding the depth of ion pair formation, ion solvent, and ion–ion interactions in solutions. In this study, the osmotic coefficients for binary gabapentin (GBP)/water and ternary GBP/DES (ChCl/EG and ChCl/U) aqueous solutions were calculated using vapor pressure osmometry measurements at T = 298.15 K and pressure 872 hPa. Water activities, osmotic coefficients, and vapor pressure depressions were all calculated for binary solutions. The Pitzer equation was used to correlate the osmotic coefficient values. Activity coefficients for GBP in the binary systems were determined by the obtained parameters of this equation. The standard deviation for the osmotic coefficient value in the binary system with the Pitzer equation is 0.0059. In ternary solutions, two different DES concentrations (about molality 1 and 3) were used to investigate the effect of concentration on osmotic coefficients. For ternary solutions, it was also possible to obtain quantities like water activity and osmotic coefficient data. Finally, the predicted values of water activity using the Lin and ECA models were applied to compare the results of water activity in the studied systems. The results showed that the ECA and Lin models have 0.00045 and 0.0011 average standard deviation, respectively.

Vapor-liquid-solid equilibria and thermodynamic study of aluminum chloride aqueous solutions at various temperatures

The vapor-liquid-solid equilibria and thermodynamics data relevant to aluminum chloride in aqueous solutions were investigated at various temperatures. The water activity measurements of AlCl3(aq) were carried out from dilution to saturated solutions at temperatures ranging from 298.15 to 353.15 K using the hygrometric method. From new experimental results, the ion interaction of Pitzer, extended ion interaction (EII) and Clegg–Pitzer–Brimblecombe (CPB) models were developed to allow the parametrization of the binary system. The interaction parameters were evaluated for the Al−Cl−H2O system and used to calculate the solute activity and osmotic coefficients form the three models. The standard approach for a 3–1 electrolyte with the ion parameters in the temperature range shows a very good agreement with osmotic coefficient data for unsaturated solutions. The solubility equilibrium of anhydrous AlCl3 in aqueous solutions was determined experimentally up to mmax=(3.383 to 3.606) mol·kg−1from (298.15 to 353.15) K respectively; then, the solubility products as LnKsp∘ of AlCl3(aq) were also given using the obtained activity coefficients at various temperatures.

Application of the multicomponent Gibbs-Duhem equation for the activity coefficient evaluation of a ternary aqueous solution with an electrolyte and a molecular solute from osmotic coefficient data

Starting from the solution of the Gibbs-Duhem equation for multicomponent systems on terms of the osmotic coefficient, a method was developed to evaluate the activity coefficients of the electrolytic and molecular solutes of a ternary aqueous solution. An analytical expression of the osmotic coefficient was proposed for the accurate description of experimental data, which is in agreement with the behaviour of the binary systems at the corresponding limiting concentrations. Then the expressions of the activity coefficients of the two solutes were derived, which satisfy the condition of state function through the equality of the cross partial derivatives. Finally, such expressions were applied to the systems water(1)-NaCl(2)-sucrose(3) and water(1)-tetrabutylammonium bromide(2)-urea(3), verifying the accuracy of the proposed method.

Experiment and Correlation of the Osmotic Coefficient for the Aqueous Solution of Weak Acids Using the NRTL-NRF Model

In this paper, experimental data of osmotic coefficients of water-weak acid binary solution were obtained via the isopiestic method at 298.15 K for six applicable weak acids including ascorbic, lactic, gallic, glycolic, isovaleric, and salicylic acids. The NRTL-NRF model of Haghtalab and Vera was developed to include water-weak acid systems. The model developed for the aqueous solution of these six acids had four parameters. Applying a numerical version of Marquardt–Levenberg’s optimization, the parameters of interaction energy of the NRTL-NRF model were estimated by minimizing the root mean square deviation between the calculated and experimental osmotic coefficient. The results revealed that the osmotic coefficient values calculated by the model were in excellent agreement with the obtained experimental values. In addition, the molality of the undissociated electrolyte (mE) was simultaneously calculated during the optimization of the parameters. Also, the activity coefficient of the undissociated part of the acid (γU) was presented.

Determination of osmotic coefficients and activity coefficients of calcium d-pantothenate, cefazolin sodium, and ceftriaxone sodium drugs in aqueous solutions of amino acids by using vapor pressure osmometry at 310.15 K

Fundamental and serious efforts have been made over the past years to improve the drug acts, which leads to the discovery of novel drug preparations and delivery systems. The optimal design of such processes requires a molecular-level understanding of the interactions between drug molecules and biomolecules such as proteins. The thermodynamic investigation provides deep insight and knowledge of solute-solvent interactions and selection of appropriate production compounds in pharmaceutical fields. Particularly, the study of drug + biomolecule in aqueous media is the central issue in many types of research. The osmotic coefficient data for aqueous solutions containing the drugs (calcium d-pantothenate (CDP), cefazolin sodium (CFZ.Na), ceftriaxone sodium (CFT.Na)) with simple amino acid, l-alanine, glycine and l-leucine are obtained at 310.15 K using vapor pressure osmometry. Activity coefficients of both components in mixture were estimated using experimental osmotic coefficients. According to the results, the values of osmotic coefficients for the ternary system (drug + water + l-leucine) with a concentration of 0.04 mol∙kg−1 are higher than those values in other systems. The concentration dependence of osmotic coefficients indicates ion-pair formation between the ions of the drugs. Finally, Lin et al. and ECA models were used to correlate the water activity data in the presence of the amino acids obtained for the aqueous solution (drug + water + amino acid).

An extended solvation theory for electrolyte osmotic and activity coefficients. Application to 1:1, 1:2, 1:3, 1:4, 2:1, 2:2, 3:1, 3:2 and 4:1 aqueous electrolyte solutions

In this work, we have used two models (DH-MS and PDH-MS) based upon the extended solvation theory to correlate osmotic and activity coefficients of electrolyte aqueous solutions. These models contain the long-range term of the Debye-Hückel (DH) theory or the Pitzer-Debye-Hückel (PDH) modification and a short-range term based upon a modified solvation (MS) theory. We have used literature experimental data of mean ionic activity and osmotic coefficients of 338 aqueous solutions. The electrolytes included in this work are type 1:1, 1:2, 1:3, 1:4, 2:1, 2:2, 3:1, 3:2, and 4:1 at 298.15 K. The results show that the DH-MS and PDH-MS models effectively correlate the experimental data within an average absolute percentage deviation of 0.588% and 0.688%, respectively. We have compared our results with those obtained from the Archer model. This model agrees within 0.769% with the literature data.

Counterion condensation theory for finite polyelectrolyte and salt concentrations

In the present work we analyze the physical fundamentals of Manning’s counterion condensation using his charged line model in a simple salt solution. We extend the theory for the cases of finite saline concentration and polymeric concentration tending to zero and the case of both finite concentrations. To find the equilibrium between the phases of free and condensed counterions, besides minimizing the free energy, we deduce an auxiliary equation to determine the two characteristic parameters of the theory, the fraction of condensed counterions and the volume of condensation. We compare the obtained results in the present work for only one infinite charged line with the ones of counterion condensation theory by Schurr and Fujimoto. We find that the linear density of critical charge depends on the concentration of added salt and takes values higher than one, instead of the unitary value predicted by Manning. We obtain the equations by the activity and osmotic coefficients in function of the critical charge density. We compare them with the corresponding equations by Manning for these parameters. We extend the counterion condensation theory to solutions of linear polyelectrolytes for finite saline and polymeric concentrations using a cell model. We modify the electrostatic contribution to the Gibbs energy adding, to the traditional one calculated by Manning, the energy excess due to the macroion present in a cylindrical cell. We apply the theory to obtain the osmotic coefficient and we compare our results with experimental data of DNA osmotic coefficient and with theoretical adjustment using the Poisson–Boltzmann equation.

Development of accurate chemical thermodynamic database for geochemical storage of nuclear waste. Part II: Models for predicting solution properties and solid-liquid equilibrium in binary nitrate systems

The main purpose of this study is to develop new thermodynamic models for solution behavior and solid-liquid equilibrium in 10 nitrate binary systems of the type 2–1 (Mg(NO3)2-H2O, Ca(NO3)2-H2O, Ba(NO3)2-H2O, Sr(NO3)2-H2O, and UO2(NO3)2-H2O), 3–1 (Cr(NO3)3-H2O, Al(NO3)3-H2O, La(NO3)3-H2O, Lu(NO3)3-H2O), and 4–1 (Th(NO3)4-H2O) from low to very high concentration at 25 °C. To construct models, we used different versions of standard molality-based Pitzer approach. To parameterize models, we used all available raw experimental osmotic coefficients data (φ) for whole concentration range of solutions, and up to supersaturation zone. The predictions of developed models are in excellent agreement with φ-data, and with recommendations on activity coefficients (γ±) in binary solutions from low to very high concentration. The Deliquescence Relative Humidity (DRH), and thermodynamic solubility product (as ln K°sp) of 12 nitrate solid phases, precipitating from saturated binary solutions have been calculated. The concentration-independent models for nitrate systems described in this study are of high importance for development of strategies and programs for nuclear waste geochemical storage.

Development of accurate chemical thermodynamic database for geochemical storage of nuclear waste. Part III: Models for predicting solution properties and solid-liquid equilibrium in cesium binary and mixed systems

The models described in this study are of high importance in the development of thermodynamic database needed for nuclear waste geochemical storage as well as for technology for extracting cesium resources from saline waters. In this study we developed new not concentration restricted thermodynamic models for solution behavior and solid-liquid equilibrium in CsF-H2O CsOH-H2O and Cs2SO4-H2O systems at 25 °C. To parameterize models we used all available experimental osmotic coefficients data for whole concentration range of solutions and up to saturation point. The new models are developed on the basis of Pitzer ion interactions approach. The predictions of new developed here models are in excellent agreement with experimental osmotic coefficients data (ϕ) in binary solutions from low to extremely high concentration (up to 21.8 mol.kg-1 for CsOH-H2O and up to 35.6 mol.kg-1 for CsF-H2O). The previously developed by Christov by Christov and co-authors and by other authors Pitzer approach based thermodynamic models for five (5) cesium binary systems (CsCl-H2O CsBr- H2O CsI-H2O CsNO3-H2O and Cs2SeO4- H2O) are tested by comparison with experimental osmotic coefficients data and with recommendations on activity coefficients (γ±) in binary solutions. The models which give the best agreement with (ϕ)- and (γ±) -data from low to high concentration up to m(sat) are accepted as correct models which can be used for solubility calculations in binary and mixed systems and determination of thermodynamic properties of precipitating cesium solid phases. The thermodynamic solubility products (ln Kosp) and the Deliquescence Relative Humidity (DRH) of solid phases precipitating from saturated cesium binary solutions (CsF(cr) CsCl(cr) CsBr(cr) CsI(cr) CsOH(cr) CsNO3(cr) Cs2SO4(cr) and Cs2SeO4(cr)) have been determined on the basis of evaluated and accepted binary parameters and using experimental solubility data. The reported mixing parameters [θ(Cs M2+) and ψ(Cs M2+ X)] evaluated by solubility approach for 15 cesium mixed ternary systems (CsCl-MgCl2-H2O CsBr-MgBr2-H2O CsCl-NiCl2-H2O CsBr-NiBr2-H2O CsCl-MnCl2-H2O CsCl-CoCl2-H2O CsCl-CuCl2-H2O CsCl-CsBr-H2O CsCl-RbCl-H2O Cs2SO4-CoSO4-H2O Cs2SeO4-CoSeO4-H2O Cs2SO4-NiSO4-H2O Cs2SeO4-NiSeO4-H2O Cs2SO4-ZnSO4-H2O and Cs2SeO4-ZnSeO4-H2O) are tabulated.

Evaluation of the activity coefficients of ternary molecular solutions from osmotic coefficient data

A method is proposed for the evaluation of the activity coefficients of a solution constituted by a solvent (1) and two non-volatile molecular solutes (2,3) from the experimental dependence of the osmotic coefficient of the ternary solution (1,2,3) on composition. A generalized analytical expression is derived to describe such dependence, based on the sum of the weighted contributions of both binary systems and the contribution due to the mixing effect. With the resulting expression and using the solution of the Gibbs-Duhem differential equation for ternary systems, the equations that allows the evaluation of the corresponding experimental activity coefficients of both solutes in ideal dilute solution reference state (molality scale) are derived. From the comparative analysis and discussion of the results obtained for three ternary systems, it was possible to verify that the proposed methodology provides a rigorous alternative to evaluate suitable values ​​of activity coefficients from experimental data of osmotic coefficients. Finally, in order to facilitate the correlation of these values with equations originated in molecular solution modelling (NRTL, UNIQUAC, etc.), the relationships between the corresponding reference states and concentration scales were established.

Thermodynamics of solvent-driven water extraction from hypersaline brines using dimethyl ether

Solvent-driven water extraction (SDWE) has promising applications in hypersaline brine desalination, including zero-liquid discharge processing for industrial wastewaters, and resource recovery, such as the extraction of lithium and rare earth elements from solution mining leachates. In this study, we develop a computational thermodynamic framework to analyze the liquid–liquid extraction of water from hypersaline brines using dimethyl ether (DME), an aprotic solvent that is partially miscible with water. The high volatility of DME enables its rapid separation from water–DME mixtures after water absorption, while its low polarity minimizes the organic-phase solubility of electrolytes, such as sodium chloride (NaCl). We first build a thermodynamic model based on the LIQUAC excess Gibbs free energy model for water–DME–NaCl mixtures. Maximum likelihood estimators for water–DME–NaCl interaction parameters are calculated through the nonlinear regression of fluid phase equilibrium and osmotic coefficient data using metaheuristic global optimization techniques. A multistage counter-current liquid–liquid separator (LLS) model is then developed to explore the water recovery and brine concentration ratios achievable as a function of feed molality and DME to feed water flow rate ratio. For a saline feed with a molality of 2.0molkg−1 (over three times the salinity of seawater) our analysis demonstrates that a one-stage LLS can achieve a water recovery ratio of 0.51 with an initial DME to saline feed molar flow rate ratio of 4.0, rising to 0.63 with a second equilibrium stage. We conclude by quantifying the amount of DME required to reach zero-liquid discharge brine salinities and analyzing the impact of staging and temperature on separation performance. Our thermodynamic model enables the rapid evaluation of SDWE systems for emerging hypersaline brine desalination and valorization applications.

Studies of thermodynamics of micellization and pattern of self-association of decyltrimethylammonium bromide in aqueous solutions at 298.15 K

Using recently reported density, thermal coefficient of expansion and internal pressure data along with the literature osmotic coefficient and enthalpy data and adopting Mass–action model, the properties of decyltrimethylammonium bromide (C10TAB) in water are studied at 298.15 K. The number density, aggregation number, equilibrium constant, standard free energy changes due to micellization, standard entropy changes due to micellization and mean ionic activity coefficient are calculated in pre–micellar and post–micellar regions of concentration assuming that the cationic surfactant C10TAB is fully dissociated in water. Characteristic pattern of association are examined through the models/concepts developed by Tanford, Mukerjee as well as by O. P. Ts’o and noted that hydrophobic interactions between the non–polar chains and water structural effects (in the form of ion–solvent and ion–ion interactions) govern the equilibrium properties of such solutions. The critical micelle concentration (cmc) value and aggregation number value agree with the literature data. It has been observed that aggregation number value decreases slightly, equilibrium constant value goes through a minimum, standard free energy changes due to micellization parameter go through a maximum while positive magnitude of entropy changes due to micellization are observed as a function of concentration of C10TAB. The variation of mean ionic activity coefficient of the salt ions with concentration indicates deviation from ideal–associative solution behaviour. All these results are interpreted on the basis of monomer–micelle equilibria existing in solution phase, affecting the solution properties through electrostatic, hydrophobic solvation and hydrophobic interaction effects.

Alternative formalism for the evaluation of the activity coefficients on ternary electrolyte solutions from osmotic coefficient data

An alternative method is presented, which is independent of any physicochemical model of the electrolyte solution, for the evaluation of the mean ionic activity coefficient in molal scale, γ±i (i: 2,3), of the solutes of a ternary solution (1–2–3), starting from experimental data of the osmotic coefficient on composition ϕexp(m,xi). It is based on the dependence of ln γ±i on ϕ originally derived by H.A.C. McKay and confirmed by S.G. Canagaratna and M. Maheswaran as a particular solution of Gibbs-Duhem equation for multicomponent systems. Its application involves the integration of both ϕ and its derivative ∂ϕ/∂mi, so that it requires a very precise correlation of the dependence ϕexp(m,xi). Therefore, in order to achieve the required precision, the theoretical expression ϕ(m,xi) is developed as the sum of three contributions, (i) ϕDH: the limiting behaviour given by the Debye-Hückel equation for multicomponent systems, (ii) ΔϕDDH: the sum of the deviations to the Debye-Hückel behaviour of the corresponding binary solutions (1–2 and 1–3) and (iii) ΔϕM: a contribution of mixing effect. Finally, introducing the resulting ϕ(m,xi) into the Gibbs-Duhem equation and operating, the corresponding expression of ln γ±i (m,xi) is derived. The capacity of the ϕ(m,xi) equation to correlate the dependence ϕexp(m,xi), the methodology employed to obtain the parameters values, as well as the ln γ±i (m,xi) resulting dependence are illustrated through its application to the analysis of two ternary systems.

Chemical and geochemical modeling. Thermodynamic models for binary fluoride systems from low to very high concentration (&gt; 35 m) at 298.15 K

Abstract In this study we developed well validated thermodynamic models for solution behavior and solid-liquid equilibrium for all fluoride binary systems, for which activity data are available. The subject of modeling study are 5 fluoride systems of the type 1-1 (HF-H2O, NaF-H2O, KF-H2O, RbF-H2O, and CsF-H2O) and one of 1-2 type (H2SiF6-H2O) from low to very high concentration at 298.15 K. Models are developed on the basis of Pitzer ion interactions approach. The recommendations on mean activity coefficients (γ±) have been used to construct the model for HF-H2O system. To parameterize models for all other 5 binary systems we used all available raw experimental osmotic coefficients data (φ) for whole concentration range of solutions, and up to saturation point. The predictions of new developed here models are in excellent agreement with experimental osmotic coefficients data, and with recommendations on activity coefficients in binary solutions from low to very high concentration: up to 20 mol. kg−1 in HF-H2O, and up to 35.6 mol.kg−1 in CsF-H2O. The Deliquescence Relative Humidity (DRH (%)) and thermodynamic solubility products (as ln Ko sp) of 4 solid phases [NaF(s), KF.2H2O(s), RbF(s), and CsF(s)] have been determined on the basis of evaluated model parameters and using experimental m(sat) solubility data.

A new NRTL-based local composition model for thermodynamic modeling of electrolyte solutions

A new local composition model for the expression of excess Gibbs energies and activity coefficients in binary and multicomponent electrolyte solutions is presented in this work. The model is based on the nonrandom two-liquid (NRTL) theory and is developed assuming the random contribution of ions and molecules around central species at reference state. The new model provides a completely new formulation for the expression of short-range interactions in electrolyte solutions. The accuracy of developed equations is examined using the available experimental data for several aqueous electrolyte systems at vast ranges of concentration and temperature. The results are compared with those obtained from eNRTL model. Two binary interaction parameters of the model are adjusted for numerous binary salt-water systems through the accurate correlation of the mean ionic activity coefficient data. Adjusted parameters are then successfully used for the prediction of osmotic coefficients in binary systems. When compared to the eNRTL model, the new model is more accurate. That superiority is very significant for the systems which are highly non-ideal. To examine the adequacy of the model for multicomponent systems, available experimental solubility and osmotic coefficient data of different ternary aqueous electrolyte systems are compared to the values predicted by the model. Using only the previously adjusted binary interaction parameters, the predicted values are in very good agreement with the experimental data.

An extensive thermodynamic study on amino acids aqueous solutions and their CO2 solubility by taking into account dipolar and quadrupolar contributions

Amino acids are significant biological components that in water form predominant species named zwitterions. They are highly dipolar molecules with negative and positive charges. Aqueous solutions of amino acids have numerous practical applications where knowing their thermodynamic behavior is essential to model, design, and optimize processes concerned with them. Although, dipole-dipole interactions play important roles in aqueous solution of amino acids, dipole-quadrupole and quadrupole-quadrupole ones make significant contributions when considering the solubility a highly quadrupolar component such as carbon dioxide in aqueous solution of amino acids, i.e., CO2 capture by an amino acid aqueous solution. According to the literature, there is still room to apply a more simple and effective thermodynamic model considering dipole-dipole interactions for water + amino acid systems where this work did so by applying Cubic-Plus-Polar (CPP) Equation of State (EoS). Moreover, water + amino acid + carbon dioxide systems were thermodynamically modeled by taking into account dipole-dipole, dipole-quadrupole, and quadrupole-quadrupole contributions which such investigation has not yet been carried out in the literature. The predictive capability of the proposed model were extensively examined by evaluating the model-calculated data of activity coefficient, osmotic coefficient, density, and water activity of numerous aqueous solutions of amino acids including glycine, alanine, α-aminobutyric acid, valine, serine, proline, threonine, leucine, cysteine, methionine, glutamic acid, histidine, and arginine at various temperatures. The osmotic coefficient of water + valine + alanine and water + valine + glycine systems were also predicted by CPP EoS. The solubility of CO2 in aqueous solution of methionine was finally calculated by the proposed model over a wide range of pressure. The quantitative and qualitative results provided by CPP EoS verified its reliability in all studied situations.

Effect of deep eutectic solvents based on choline chloride on the thermodynamic and transport properties of D-fructose in aqueous solution

In this work, the effect of some deep eutectic solvents (DESs) based on choline chloride on the thermodynamic and transport properties of D-fructose in aqueous solutions was investigated. Using the vapor-liquid equilibrium (VLE) data, water activity (aw), osmotic coefficient and vapor pressure data were obtained. The performance of different local composition models such as Wilson, e-NRTL, and UNIQUAC for correlating of these data have been examined. The calculated negative values of Gibbs free energies of transfer (ΔGtri) indicate favorable interaction of DESs with D-fructose. Further, the standard partial molar volumes Vφ0, partial molar isentropic compressibility Kφ0, viscosity B-coefficient and molar refractions RD for the solutions have been calculated from the measured density and speed of sound, viscosity and refractive index data at T = (288.15 to 318.15) K. Interaction volume Vint and cavity volume Vcav have been computed from scaled particle theory (SPT) to probe solute-solvent interactions. The viscosity B-coefficients was used to discuss structure-making tendency of the solutions studied.

Molecular simulation of osmometry in aqueous solutions of the BMIMCl ionic liquid: a potential route to force field parameterization of liquid mixtures.

Despite widespread development and use of ionic liquids (ILs) in both academic and industrial research, computational force fields (FFs) for most of those are not available for a precise description of inter-species interactions in aqueous environments. In the scope of this study, by means of molecular simulations, the osmotic coefficient of an aqueous solution of an IL is calculated and used as a basis to reparameterize popular IL-FFs existing in the literature. We first calculate the osmotic coefficients (at 298.15 K and 1 atm pressure) of aqueous solutions of 1-butyl-3-methylimidazolium chloride (BMIMCl), a generic IL, popularly used in biomass processing and the subsequent conversion to value-added intermediates. The performance of two popular atomic, nonpolarizable FFs developed for BMIMCl, one by Lopes, Pádua, and coworkers (FF-LP) and the other by Sambasivarao, Acevedo, and coworkers (FF-SA), when mixed with the SPC/E water model, is tested with respect to their ability to reproduce the experimental osmotic coefficient data. Interestingly, the osmotic coefficient is found to be increasing with a gradual increase in IL molality within the concentration range of our investigation, which is contrary to the experimental trend reported in the literature for the same IL-water mixture. Henceforth, necessary corrections to the nonbonded ion-ion and ion-water interactions are made to match the experimental osmotic coefficient. To further assess the reliability of the new FF, we extensively explore the thermodynamic (density, isothermal compressibility, and thermal expansion coefficient), dynamic (diffusivity and viscosity), and association/dissociation properties (rationalized with the help of radial distribution functions) with both the original and reparameterized FF for a wider range of concentrations up to a molality of 18.50 mol kg-1. The calculated quantities are compared against experimental data wherever available. The modified FF parameters exhibit significant improvements in terms of its ability to match experimental solution properties, such as density, viscosity, association/dissociation, etc. We report that excessive dissociation of BMIMCl in water is responsible for the shortcomings observed in the original FFs and improved prediction of physicochemical properties could be achieved using the modified FFs.