Osmotic Coefficients Research Articles

Relationship of PEG-induced precipitation with protein-protein interactions and aggregation rates of high concentration mAb formulations at 5 °C

Native protein-protein interactions can play an important role in determining the tendency of monoclonal antibodies (mAbs) to aggregate under storage conditions. In this context, phase separation of mAb solutions induced by the addition of neutral polymers such as poly(ethylene glycol) (PEG) represents a simple method to assess the tendency of proteins to self-associate in the native state. Here, we investigated their relationships between PEG-induced phase separation, protein-protein interactions and long-term aggregation rate of several formulations of four mAbs at 100 mg/mL and 5 °C over 12 weeks of storage.We observed that the location of the phase boundary correlated well with the osmotic second virial coefficient B22 determined in absence of the polymer, indicating that for our solutions PEG primarily leads to depletion forces between protein molecules, which are additive to protein-protein interactions.However, limited correlation between aggregation rate at 5 °C and phase behavior was observed across different mAbs, pH values and ionic strengths, indicating that colloidal stability is not the only determinant of aggregation even at such low temperature and high protein concentration. Our results contribute to the growing realization that aggregation propensity in the context of antibody developability is a complex feature, which depends on a variety of biophysical properties rather than one single parameter.

Application of hard-core Exponential-6 intermolecular potential function to determine the second osmotic virial coefficients of polymer solutions

The osmotic pressures of polymer solutions are related to their corresponding osmotic virial coefficients. There are several experimental methods to determine the osmotic virial coefficients. However, these experimental virial coefficients are restricted to the experimental conditions. An alternative way of determining the osmotic virial coefficient is with the help of statistical thermodynamics, and unlike experimental methods, because of its theoretical basis, it is not restricted to limited ranges of experimental conditions. The osmotic virial coefficients can be used to calculate the different properties of polymers and polymer solutions, such as the average molecular weight of the polymer (M) and the theta temperature. In this work, for the first time, the second osmotic virial coefficients of a number of polymeric solutions are calculated using the Kihara and Exponential-6 intermolecular potential functions. Furthermore, the hard-core Exponential-6 model, that we have proposed, is also investigated. Additionally, the molecular weights and theta temperatures of these solutions are determined using the calculated second virial coefficients and are compared to literature data. The results show that the recent hard-core Exponential-6 potential model is more accurate than the Kihara and Exponential-6 models and is applicable for calculating other properties of the polymers and polymer solutions.

Thermodynamics of N-Isopropylacrylamide in Water: Insight from Experiments, Simulations, and Kirkwood–Buff Analysis Teamwork

The behavior of thermoresponsive polymer poly(N-isopropylacrylamide) (PNiPAM), an essential building block in the design of smart soft materials, in aqueous solutions has attracted much interest, which contrasts with our knowledge of N-isopropylacrylamide (NiPAM) monomer. Strikingly, the physicochemical properties of aqueous NiPAM are similarly rich, and their understanding is far from being complete. This stems from the lack of accurate thermodynamic data and quantitative model for atomistic simulations. In this joint study, we have probed the thermodynamic behavior of aqueous NiPAM by experimental methods, molecular dynamics (MD) simulations, and Kirkwood-Buff (KB) analysis at ambient conditions. From the partial molar volumes and simultaneously correlated osmotic coefficients, with excess partial molar enthalpies of NiPAM in water, the concentration and temperature dependence of KB integrals was determined. For the purpose of this work, we have developed and employed a novel NiPAM force field, which not only reproduces KB integrals (Gij) and adequately captures macroscopic thermodynamic quantities but also provides more accurate structural insight than the original force fields. We revealed in the vicinity of NiPAM the competing effect of amide hydration with interaction between nonpolar regions. This microscopic picture is reflected in the experimentally observed NiPAM-NiPAM association, which is present from highly dilute conditions up to the solubility limit and is evidenced by G22. From intermediate concentrations, it is accompanied by the existence of apparent dense-water regions, as indicated by positive G11 values. The here-employed KB-based framework provided a mutually consistent thermodynamic and microscopic insight into the NiPAM solution and may be further extended for ion-specific effects. Moreover, our findings contribute to the understanding of thermodynamic grounds behind PNiPAM collapse transition.

Model of Forward Osmosis through composite/asymmetric membranes: Effects of support inhomogeneity and solution non-ideality

The processes of Forward Osmosis and Pressure-Retarded Osmosis are strongly influenced by Internal Concentration Polarization occurring within their porous supports. Models of this important phenomenon usually assume that the support layer can be described by using a single space-independent value of effective diffusion coefficient of solute (or S-parameter). At the same time, FO/PRO supports are known to be not macroscopically homogeneous. Via a simple transformation of a modified convection-diffusion equation we show that the simple model with a constant effective diffusion coefficient is applicable to macroscopically inhomogeneous supports provided that this coefficient is understood as the harmonic average of the space-dependent one. Using the arithmetic average porosity leads to an overestimation of draw solute diffusivity within the support layer. The effects of draw solute non-ideality were explicitly and rigorously accounted for. We also demonstrate theoretically that the same harmonic average diffusive hindrance factor can be estimated from direct measurements of diffusion across the membrane supports if those are separately available. The effects of non-ideality are strongly dependent on draw solute choice. It is shown that, in the case of NaCl and KCl, draw solute non-ideality has fairly limited implications for FO and PRO flux prediction. In the case of MgSO4, non-ideality significantly influences expected fluxes: ignoring non-ideality leads to an overestimation of fluxes by a factor of two. In the case of MgCl2, despite strong solute non-ideality, the error is relatively limited, due to an increase of the osmotic coefficient offsetting a decrease of diffusivity as a function of MgCl2 concentration.

Benefits of the Electronic Continuum Correction in Bio-Force Fields

The interplay between charged groups in biosystems is ubiquitous. They are crucial when considering ions, but also for many other biomolecules. Interestingly, the amount of evidence suggesting an overestimation of the interaction between charged groups in classical molecular dynamics (MD) simulations for biosystems keeps increasing. Notorious examples are lipid membranes, proteins rich in charged amino acids, and even charged sugar biopolymers when interacting with other charged species. Furthermore, the overestimation is especially dramatic when interacting with divalent ions like Ca2+. MD force fields have started to introduce empirical corrections (NBFIX). These corrections artificially increase the interatomic distance between charged atoms, effectively reducing overbinding. There is, however, a reason behind the overbinding. MD simulations can correctly capture the nuclear part of the molecular polarization, which wants to orient any molecule to the local electric field. However, they miss the electronic polarizability, which ultimately shields interacting charges. The electronic continuum correction (ECC) can recover this missing contribution. This mean-field approach provides a cheap while physically sound fix that mostly consists of scaling down the partial charges within a charged group. In this work, we present the ECC correction for the widely used CHARMM36 force field. We provide five lipid families (PI, PC, PE, PS, and PG), charged amino acids, and few sugar moieties (Glucuronic, iduronic and sialic acids). We show that the ECC correction dramatically improves their interaction with other charged groups when comparing to osmotic coefficients or NMR data. We also show that the resulting molecular structure is not worsened as compared to the original force field. Occasionally, the structure is even improved when benchmarked against experimental Raman/NMR spectra of the moieties in solution. Overall, our results show how CHARMM36 can benefit from the adoption of the ECC approach for future improvements.

Effect of molecular shape of suspended colloids on an osmotic flow across a fibrous membrane

Effects of colloid molecular shape on osmotic reflection coefficients (σv) in a liquid-filled hexagonal array of cylinders are investigated by employing lubrication theory. Results demonstrate that, for spheroids with equal Stokes-Einstein radius (aSE), an increase in the deviation from unity of the axial ratio (γ) corresponds to an increased σv. If the fiber matrix geometry is that of the quasiperiodic substructure of the glycocalyx layer adjacent to endothelial surfaces, believed to be the primary barrier for serum albumins, σv of a spheroid with aSE close to that of serum albumins is larger than σv of a sphere, and close to experimentally obtained σv of serum albumins even when the electrostatic interaction is not included, suggesting that serum albumin molecular shape contributes to its ability to prevent intravascular fluid extravasation, and, given the close correspondence between osmotic and filtration reflection coefficients, helps minimize albumin loss from microcirculation.

Standard Gibbs energy of metabolic reactions: V. Enolase reaction

The glycolytic pathway is one of the most important pathways for living organisms, due to its role in energy production and as supplier of precursors for biosynthesis in living cells. This work focuses on determination of the standard Gibbs energy of reaction ΔRg′0 of the enolase reaction, the ninth reaction in the glycolysis pathway. Exact ΔRg′0 values are required to predict the thermodynamic feasibility of single metabolic reactions or even of metabolic reaction sequences under cytosolic conditions. So-called “apparent” standard data from literature are only valid at specific conditions. Nevertheless, such data are often used in pathway analyses, which might lead to misinterpretation of the results. In this work, equilibrium measurements were combined with activity coefficients in order to obtain new standard values ΔRg′0 for the enolase reaction that are independent of the cytosolic conditions. Reaction equilibria were measured at different initial substrate concentrations and temperatures of 298.15 K, 305.15 K and 310.15 K at pH 7. The activity coefficients were predicted using the equation of state electrolyte Perturbed-Chain Statistical Associating Fluid Theory (ePC-SAFT). The ePC-SAFT parameters were taken from literature or fitted to new experimentally determined osmotic coefficients and densities. At 298.15 K and pH 7, a ΔRg′0(298.15 K, pH 7) value of −2.8 ± 0.2 kJ mol−1 was obtained. This value differs by up to 5 kJ mol−1 from literature data. Reasons are the poorly defined “standard” conditions and partly undefined reaction conditions of literature works. Finally, using temperature-dependent equilibrium constants and the van ‘t Hoff equation, the standard enthalpy of reaction of ΔRh′0(298.15 K, pH 7) = 27 ± 10 kJ mol−1 was determined, and a similar value was found by quantum-chemistry calculations.

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.

Determination and application of osmotic suction of saline solution in clay

Osmotic suction affects the mechanical properties of the clay and exists as long as the solute is present in pore water of soil. Determination of osmotic suction of pore solution is significant for quantitatively explaining the mechanical behaviors of clay in saline solution. This paper aims to introduce a calculation method to determine the osmotic suction of saline solutions and the application of the osmotic suction to quantify the mechanical behaviors of clay in saline solutions. Osmotic coefficient as the bridge connecting ion concentration and osmotic suction was calculated by a simplified half-empirical equation and verified by published experimental data. Then the osmotic suctions were achieved using the calculated osmotic coefficients, and two filter paper methods were carried out to verify the calculated results. The consistency between the experimental results and the calculated ones proved the correctness of the proposed method for calculating the osmotic suction. A step further, the mechanical behaviors of clay in saline solutions were explained and quantified from the microscopic with the concept of microstructural effective stress and the macroscopic with the concept of modified effective stress, both related to the osmotic suctions.

Theory of Multicomponent Phenomena in Cation-Exchange Membranes: Part I. Thermodynamic Model and Validation

We present and validate a mathematical model for multicomponent thermodynamic activity in phase-separated cation-exchange membranes (e.g., perfluorinated sulfonic-acid ionomers). The model consists of an expression for the free energy of the membrane and of the surrounding electrolyte solution. A modified Stokes-Robinson ionic solvation framework treats the solution-like non-idealities resulting from hydration, electrostatics, ion association, and physical interactions in bulk solution and in ionomer hydrophilic domains. Inside the membrane, a mechanics-based composite approach accounts for the swelling of the hydrophobic matrix. Treating the membrane microstructure as a disordered system of domains calculates steric exclusion of ions. Electroneutrality guarantees that the charge of mobile ions in the membrane is equal to the charge on polymer groups. Osmotic coefficients for electrolytes from literature parameterize solution-like interactions while mechanical and X-ray scattering characterization gives most membrane-specific parameters. Model predictions compare favorably to measured membrane thermodynamics (i.e., water and ion uptake) in dilute and concentrated binary and ternary salt electrolytes and in water vapor. Interactions between ions in the membrane are similar to those present in bulk electrolytes. Our results reveal that water and ion uptake is dictated by a balance between solution-like energetics and membrane swelling.

Prediction of activity and osmotic coefficients of fission product systems CsOH + CsX (X = Cl, Br, I) at 298.15 K

The activity and osmotic coefficients of fission product systems CsOH + CsCl, CsOH + CsBr and CsOH + CsI are of importance for studying the removal of cesium ions from radioactive wastewater and the hygroscopic growth of its aerosols. Various mixtures of alkali metal hydroxides and their halides are selected as the verification systems. Results indicate that the prediction effects of electrolyte MIVM (eMIVM) are better than that of Pitzer’s equation. Then, the activity coefficient, osmotic coefficient and excess Gibbs energy of the above mentioned systems are further predicted by both models. It is found that the predicted values of eMIVM are more reliable and reasonable.

Mean Activity Coefficients of KCl in KCl + SrCl2 + H2O Ternary System at 288.15 K Determined by EMF Method.

In this work, the studies of thermodynamic mean activity coefficients of KCl in the KCl-SrCl2-H2O ternary system have been made. A cell without liquid junction battery cell, K-ISE|KCl(mA), SrCl2(mB)|Cl-ISE, was used to study the activity coefficients in this mixed system KCl-SrCl2-H2O at 288.15 K by the electromotive force method. The total ionic strengths ranges are 0.0100-1.0000 mol·kg-1 with different ionic strength fractions yb of SrCl2, that is, yb = (0, 0.2, 0.4, 0.6, and 0.8). The results show that the K-ISE and Cl-ISE have a good Nernst response. Accordingly, the electromotive forces of the mixed system were measured by using the ion selective electrode listed above, and the mean activity coefficients are also determined with Nernst equation. Using the activity coefficient data, the mixed ion interaction parameters θK,Sr and ψK,Sr,Cl of Pitzer equations at 288.15 K were fitted by Matlab with linear regression method, respectively. Furthermore, those parameters were applied to calculate the values of the mean activity coefficients of SrCl2. Finally, the osmotic coefficients, water activity, and the excess Gibbs free energy of this system were evaluated by Pitzer's equations.

Thermodynamic equilibrium of solid – liquid and solutions of system [formula omitted] at various temperatures

The thermodynamic equilibrium of solid–liquid and solutions of the mixed system of sodium and hydrogen fluorides were investigated at various temperatures. The chemical speciation of the NaF-HF in aqueous solutions was described; which the considered equilibrium is dissociating into the species Na+(aq), H+(aq), HF(aq), F-(aq), HF2-(aq) and H2F3-(aq). The species molalities are strongly dependent on the concentration in the solution, therefore directly influence the thermodynamic properties. Neglecting this concentration dependence leads to erroneous osmotic coefficients for weak electrolyte solutions. Then, the water activity measurements of the mixed system yHF+1-yNaFaq were performed at various temperatures from 298.15 K to 353.15 K using the hygrometric method. These measurements were made as a function of total molality ranging from dilution to saturation for different ionic-strength fractions y with respect to the support solute HF with y = 0.20, 0.50, and 0.80. The mixed aqueous electrolytes were considered as a polyelectrolyte system [Na+-HF0-H+-F--HF2--H2F3--H2O]. Based on the ion interaction model, the thermodynamic model was developed to describe the behavior of sodium and hydrogen fluorides in aqueous solutions at different temperatures. The species molalities of the HF(aq), Na+(aq), H+(aq), F-(aq), HF2-(aq) and H2F3-(aq) of the system were evaluated. The new ion interaction parameters ΦH+, Na+ and ΨH+, Na+,F- were determined at various temperatures and used to calculate the species activity coefficients as a function of total molality for different ionic-strength fractions (y). The developed model exhibits a high consistency for the treatment of polyelectrolyte system. The results allow describing the behavior of the mixed NaF-HF in aqueous solutions. The solubility of the sodium fluoride in hydrofluoric acid aqueous solutions were also performed, and the formed solid phases were characterized by X-ray diffraction analysis. The obtained crystal forms were identified to NaF (s) and NaHF2(s) for y = 0.20 and y= (0.50 and 0.80) respectively.

Thermodynamic modeling of gas solubility in aqueous solutions of quaternary ammonium salts with the e-CPA equation of state

The study of gas solubility in aqueous electrolyte solutions is important, e.g. for hydrate applications, and it is also a challenging task, as metal halide salts show salting-out effects on gas in water, while some quaternary ammonium salts (QAS) show salting-in effects. This work presents a modeling study of gas solubility in aqueous solutions of several QAS (tetra-n-methyl-ammonium bromide, tetra-n-ethyl-ammonium bromide, tetra-n-propyl-ammonium bromide and tetra-n-butyl ammonium bromide) with the electrolyte Cubic-Plus-Association Equation of State (e-CPA). The ion size and ion-water interaction parameters are obtained by fitting the experimental data of mean ionic activity coefficients and osmotic coefficients of corresponding binary mixtures. The results show that e-CPA can reasonably correlate the mean ionic activity coefficients of QAS in aqueous solutions. The ion-gas interaction parameters are obtained by fitting the experimental data of gas solubility and the results show that e-CPA can correlate the gas solubilities (for nitrogen, carbon dioxide, methane and ethane) reasonably well from a quantitative point of view. For example, e-CPA gives deviations of 9.2% and 5.7% for the solubilities of carbon dioxide and methane in TBAB, respectively. The salting-in and salting-out effects and the influencing factors are also studied.

Identifying Key Residues That Drive Strong Electrostatic Attractions between Therapeutic Antibodies.

Attractive electrostatic protein-protein interactions (PPI) necessarily involve identifying oppositely charged regions of the protein surface that interact favorably. This cannot be done reliably if one only considers a single protein in isolation unless there are obvious charge "patches" that result in extreme molecular dipoles. Prior work [ J. Pharm. Sci. 2019 , 108 , 120 - 132 ] identified three monoclonal antibodies (MAbs) that displayed experimental behavior ranging from net repulsive to strongly attractive electrostatic interactions. The present work provides a systematic computational approach for identifying the origin of diverse PPI, in terms of which sets of amino acids or individual amino acids are most influential, and determining if there are different patterns of pairwise amino acid interaction "maps" that result in different behaviors. The charge was eliminated computationally, one by one, for each charged residue in the wild-type sequences, which resulted in predicted changes in the second osmotic virial coefficient. The results highlight interaction "maps" that correspond to cases with qualitatively different net electrostatic PPI for the different MAbs and solution conditions, as well as key sets of residues that contribute to strongly attractive PPI. A more computationally efficient method is also proposed to identify key amino acids based on Mayer-weighted interaction energies.

Thermodynamic properties of MCl (M = Na, K, Rb, Cs) + tetramethylurea + water ternary system at 298.2 K

For this article, a number of thermodynamic properties for MCl (M = Na, K, Rb, Cs) in tetramethylurea (TMU)-water ternary systems were investigated through potentiometric method at the temperature of 298.2 K. To fit experiment data, the Pitzer equation and the extended Debye-Hückel equation were used. The mean activity coefficients, together with excess Gibbs free energy, osmotic coefficients and standard solubility product of ternary systems are calculated. The variation of these properties in this εr-decreasing co-solvent (TMU-H2O) is discussed from the aspect of ion radius, relative permittivity, ion-ion interactions and ion-solvent in the solution.

New thermodynamic data for KNO3-sucrose-water ternary system: Water activity, osmotic coefficient, activity coefficient, excess Gibbs energy, solubility and transfer Gibbs energy at 298.15 K

On the basis of the measurement of relative humidity, the hygrometric method is used to determine the new thermodynamic data of water activity and osmotic coefficient of water-sucrose-potassium nitrate system in the wide range of KNO3 molality, varying from 0.10 to 3.00 mol kg−1 and for various contents of sucrose (0.10, 0.30, 0.5, 1.00, 2.00, 4.00, and 6.00 mol kg−1). The experimental results are compared with the predictions of the extended composed additivity (ECA) rule, the Lin et al. equation, and Lietzke and Stoughton (LS II) models. The Pitzer-Simonson-Clegg model is employed to correlate these data and calculate the other thermodynamic properties such as, the stoichiometric ionic mean activity coefficient of KNO3, the excess Gibbs energy, the solubility in aqueous solution of the studied system and the transfer Gibbs energy of KNO3 from water (W) to sucrose-water (W + S) mixtures. The different interactions that occur in the ternary solution between water, sucrose and KNO3 are discussed.

Predicting protein-protein interactions using the ePC-SAFT equation-of-state

Within the last decade, thermodynamic models have increasingly grown into the pharmaceutical industry, becoming an essential part in both, process development, as well as formulation development of small-molecule drugs. They are to an increasing degree accepted as a valuable building block to evaluate e.g. small-molecule formulation conditions. In contrast, modeling of highly complex (bio)-molecules (e.g. monoclonal antibodies) remains a challenging task and thermodynamic modeling is only rarely applied for e.g. protein formulations in the biopharmaceutical industry.Within this work, we developed a thermodynamic modeling approach to access protein-protein and protein-excipient interactions (via second osmotic virial coefficients B22 and cross viral coefficients B23) for immunoglobulin G (IgG) and bovine serum albumin (BSA) in the presence of different excipients (NaCl, sucrose, L-histidine, L-arginine) at defined buffer conditions using the ePC-SAFT equation-of-state. The pure component parameters of IgG were determined based on the amino acid sequence and further fitted to experimentally determined static light scattering signals of IgG at buffer conditions. This approach allows to predict protein-protein and protein-excipient interactions of BSA and IgG in the presence of different excipient types and thus give access to protein phase behavior in these complex solutions. Applying this approach further allows to gain a mechanistic understanding on the complex interactions in solution that govern the phase behavior, and thus can aid an optimized formulation development.

Heat capacity of Rb2SO4(aq) and Cs2SO4(aq) solutions and thermodynamic modelling of (Rb2SO4 + H2O) and (Cs2SO4 + H2O) systems

Specific heat capacity of Rb2SO4(aq) and Cs2SO4(aq) solutions was determined using a Calvet-type calorimeter from 288.15 K to 338.15 K and from about 0.25 mol·kg−1 to concentration near room temperature solubility limits. For both Rb2SO4(aq) and Cs2SO4(aq) solutions, the specific heat capacity decreases with the increase of molality at constant temperature. Combining the heat capacity data determined in this study and other thermodynamic properties (i.e. water activity, osmotic coefficient, mean ionic activity coefficient, enthalpy of dilution and solubility) reported in literature, thermodynamic and phase equilibria properties of the binary Rb2SO4 + H2O and Cs2SO4 + H2O systems were modelled using a comprehensive thermodynamic framework, in which a Pitzer-Simonson-Clegg model was applied to represent the non-ideality of aqueous phases. The models can represent all the properties over wide temperature and concentration ranges. This study forms a basis for solubility prediction in multi-component systems containing Rb and Cs sulfates.

Experimental studies and thermodynamic modeling on vapor-liquid equilibrium of aqueous solutions containing 1-butyl-1-methylpyrrolidinium trifluoromethanesulfonate ionic liquid, (d+)-Galactose, (d-)-Fructose, (d+)-Lactose and sucrose at 298.15 K

Vapor-liquid equilibrium for aqueous solutions of 1-butyl-1-methylpyrrolidinium trifluoromethanesulfonate ([bmpl][otf]) + (d+)-galactose, [bmpl][otf] + (d-)-fructose, [bmpl][otf] + (d+)-lactose and [bmpl][otf] + sucrose was investigates at 298.15 K. For this purpose, water activity in these systems was measured using an improved isopiestic method at T = 298.15 K. Osmotic coefficient of ionic liquid and vapor pressure of solutions were calculated from measured water activity data. NRTL, NRF-NRTL, mNRTL, Wilson and TNRF-mNRTL local composition based models were used to correlate the water activity data for binary and ternary aqueous solutions containing ionic liquid and saccharides considered in this work. All of these models predicted satisfactorily water activity data for the systems investigated. Water activity data and vapor pressure decreasing were utilized to highlight the solute-solvent interactions.