Apparent Molar Compressibility Research Articles

Interaction of homologous series of amino acids with sarcosine in presence of denaturant: Volumetric and calorimetric approach

Densities (ρ) and speeds of sound (u) of homologous serious of five amino acids: glycine, l-alanine, dl-α-amino-n-butyric acid, l-valine, and l-leucine were measured in aqueous 1.0mol·dm−3sarcosine and (1.0mol·dm−3sarcosine+1.0mol·dm−3urea) solutions. The values of corresponding apparent molar volume (V2,ϕ), apparent molar compressibility (KS,2,ϕ) were calculated from the density and speed of sound data at T=298.15K. Enthalpies of dilution (q) of amino acids from water to 1.0mol·dm−3sarcosine and (1.0mol·dm−3sarcosine+1.0mol·dm−3urea) solution were also measured. By linear regression fitting, the values of standard partial molar volume (V2,m0) and partial molar compressibility (KS,2,m0) and standard enthalpy of dilution (ΔtrΔdilH0) were determined. The contribution of zwitterionic and hydrophobic groups of amino acids to V2,m0 were also calculated from linear regression fitting of V2,ϕ values. The different cosolvent interactions were interpreted on the basis of cosphere overlap model. The results suggest the dominance of ionic–ionic and hydrophilic–ionic group interactions over hydrophobic–hydrophilic and ionic–hydrophobic interactions.

Studies on ionic solvation behavior of ionic liquid (tetrabutylphosphonium tetrafluoroborate) in some liquid media by volumetric, viscometric, and acoustic measurements

Physicochemical properties such as density (ρ), viscosity (η), ultrasonic speed (u) of ionic liquid tetrabutylphosphonium tetrafluoroborate in acetonitrile, tetrahydrofuran, 1,3-dioxolane, and their binaries have been studied over the entire range of composition at 298.15°K. Apparent molar volumes (ϕ V ) and viscosity B-coefficients supplemented with the data of densities and viscosities, respectively, have been interpreted in terms of ion–solvent interactions. The limiting apparent molar volumes (ϕ V 0 ), experimental slopes (S V ∗ ) derived from the Masson equation, and viscosity A and B-coefficients analyzed by the Jones–Dole equation have also been interpreted. The adiabatic compressibility (β) has been evaluated using the ultrasonic speed (u) values. Thereafter, limiting apparent molar adiabatic compressibilities (ϕ K 0 ) have been evaluated and discussed for the same.

Physico-chemical study of lithium perchlorate in alkanols (C3–C5) with the manifestation of solvation consequences

Electrical conductances of lithium perchlorate have been measured in pure n-Propanol, n-Butanol and n-Pentanol at 298.15K. Association constants (KA), limiting molar conductances (Λ0), and co-sphere diameter (R) for ion-pair formation have been analysed using Fuoss conductance equation (1978). Apparent molar volume (ϕV), viscosity B-coefficient and molar refraction (RM) have been determined from measurement of density (ρ), viscosity (η), refractive index (nD) and speed of sound (u) respectively. The limiting apparent molar volume (ϕV0) and experimental slope (SV⁎) obtained from the Masson equation have been interpreted in terms of ion–solvent and ion–ion interactions respectively. The derived parameters A and B obtained from Jones–Dole equation represent ion–ion and ion–solvent interactions respectively. Molar refraction (RM) has also been calculated using the Lorentz–Lorenz equation. The adiabatic compressibility (βS) and limiting apparent molar adiabatic compressibility (ϕK0) have been evaluated using the u values.

Studies on molecular interactions of some sweeteners in water by volumetric and ultrasonic velocity measurements at T = (20.0–45.0 °C)

Densities and ultrasonic velocity values for aqueous solutions of two sweeteners viz., maltose monohydrate and acesulfame-K have been measured as a function of concentration at 20.0–45.0°C and atmospheric pressure. Solutions of acesulfame-K were treated as electrolyte, while maltose was considered as non-electrolyte. The apparent molar and specific volumes, their isentropic apparent molar and specific compressibilities, as well as their compressibility hydration numbers have been calculated and reported. Negative deviations from Debye–Huckel limiting law of apparent molar volume for acesulfame-K was obtained at given temperatures and can be used as a direct measure of the ion–ion and ion–solvent interactions. Furthermore, apparent specific volumes of the solutes were calculated and it was found that these values of the investigated solutes lie on the borderline between the values reported for sweet substances. The partial molar expansibility, its second derivative values, (∂2V0/∂T2) and thermal expansion coefficient have been estimated.

Physicochemical study of solute–solute and solute–solvent interactions of l-phenylalanine in (water + arabinose/glucose/sucrose) solutions at different temperatures

The values of density, ρ and ultrasonic speed, u of solutions of l-phenylalanine in aqueous-carbohydrate solvents (2.5 and 5% of arabinose/glucose/sucrose, w/w in water) at T=(293.15, 298.15, 303.15, 308.15, 313.15, and 318.15)K; and viscosities, η of these solutions at (298.15, 303.15, 308.15, 313.15, and 318.15)K and at atmospheric pressure were measured. From these experimental results, the apparent molar volume, Vϕ, limiting apparent molar volume, Vϕ° and the slope, Sv, transfer volume, Vϕ,tr°, apparent molar compressibility, Ks,ϕ, limiting apparent molar compressibility, Ks,ϕ° and the slope, Sk, transfer volume, Vϕ,tr°, transfer compressibility, Ks,ϕ,tr°, limiting apparent molar expansivity, Eϕ°, Hepler’s constant, (∂2Vϕ°/dT2), Falkenhagen Coefficient, A, Jones–Dole coefficient, B and hydration number, nH were calculated. The Gibbs free energies of activation of viscous flow per mole of solvent, Δμ1°# and per mole of solute, Δμ2°#, entropies, ΔS° and enthalpies, ΔH° of activation of viscous flow were also calculated and discussed in terms of transition state theory. The structure-making/breaking ability of the amino acid has also been discussed in terms of the sign of (∂2Vϕ°/dT2) and dB/dT. The results have been interpreted in terms of solute–solvent and solute–solute interactions in these systems.

Acoustical and Volumetric Studies of Proline in Ethanolic Solutions of Lecithin at Different Temperatures

In this paper, densities (d), sound velocities (v), and viscosities (� ) of proline in 0.5, 1.0 and 1.5% (w/v) ethanolic solution of lecithin have been measured between 25-40 � C at an interval of 5 � C. The apparent molar volume (� vand apparent molar adiabatic compression (� � � have been calculated using density and velocity of sound data. These parameters were found to be sensitive towards the interactions prevailing in the studied lipid- proline-ethanol systems. The analysis of the data suggests thatv and � � values are positive in all the systems at all temperatures and decrease sharply on addition of proline showing a minimum between 6.5-7.8 mmol · kg −1 thereafter the decrease, is almost linear. These parameters are found to be consistent with temperature as well over the entire concentration range. The viscosity data have been analyzed by using Jones-Dole equation to evaluate viscosity B coefficients, the results of which have been discussed in terms of solute- solvent interactions. FTIR studies further substantiate the fact that proline molecules tend to polymerize showing maximum aggregation in the region between 6.5-7.8 mmol · kg −1 as is evident from N H and C O stretching frequencies.

Micellar interaction study of synthetic antioxidant (BHA) and sodium dodecyl sulfate (SDS) in aqueous solution for potential pharmaceutical/food applications

Butylated hydroxyanisole (BHA) is a potential phenolic antioxidant which has a wide range of pharmacological actions, whereas, sodium dodecyl sulfate (SDS) is well known to form colloidal aggregates which can be employed for biological processes, and as effective vehicles for delivery and transport phenomena. Therefore, it would be interesting to evaluate the interactions between BHA-SDS and impact of BHA-SDS micellar properties. Aggregation in terms of CMCs and thermo-acoustic properties via specific conductivity (κ), viscosity (η), compressibility coefficient (β), apparent molar volume (ϕv) and apparent molar adiabatic compressibility (ϕk) of SDS in aqueous solutions containing BHA at different temperatures (25, 30, 35 and 40°C) have been measured. Proton NMR analysis was performed in the absence and presence of BHA. Interactions were evaluated in terms of chemical shifts and moreover provided perceptivity on the location of BHA within the micelle. The results revealed the significant contribution of BHA to promoting the micelle formation much earlier with regard to increase in concentration and temperature. Convincingly, this study not only casts light on the binding interactions but also provides a hint to utilizing the micellar system in stabilization and maintenance of pharmaceutical and food materials.

Apparent molar volume and ultrasonic studies on some bile salts in water–aprotic solvent mixtures

Apparent molar volume, ultrasonic velocity and absorption studies have been carried out in aqueous solutions of some bile salts namely sodium cholate and sodium deoxycholate containing 10% (v/v) of dioxane, dimethyl sulphoxide, dimethyl formamide, tetrahydrofuran and acetonitrile. These studies are carried out in the bile salt concentration of 1–15mM at a fixed frequency of 2MHz and at a fixed temperature of 303.15K. The variation of apparent molar volume and ultrasonic velocity in aqueous solutions of bile salts containing 10% (v/v) of dioxane, dimethyl sulphoxide, dimethyl formamide, tetrahydrofuran and acetonitrile with bile salt concentration exhibiting break at critical micelle concentration (CMC). The observed absorption increases with increasing bile salt concentration and also exhibiting a break at CMC similar to velocity curve. The results are discussed in terms of formation of bile salt micelles through hydrophobic interaction and hydrogen bonding. The results obtained from apparent molar volume, ultrasonic velocity and apparent molar compressibility studies are confirmed by the equivalent conductance measurements carried out in the solutions of bile salts.

A physicochemical study of SDS in aqueous solution of Furosemide: Effect of DMSO on surfactant-Furosemide interaction

Micellization behaviour of sodium dodecyl sulphate (anionic surfactant) has been studied in the presence of Furosemide (cardiovascular drug) at two concentrations i.e. 0.001 and 0.002M in 8.0mol% aqueous solution of dimethylsulphoxide using conductance (κ), densities (d), velocities of sound (v) and viscosities (η) studies in the temperature range 20–40°C at an interval of 5°C. The critical micelle concentration (cmc) of sodium dodecyl sulphate (SDS) was determined from the plots of specific conductance (κ) of SDS. The results showed that critical micelle concentration (cmc) values of surfactant decrease with increase in [Furosemide] and increase with the rise in temperature. By using cmc data, various thermodynamic parameters like standard enthalpy of micellization (ΔHmo), standard entropy of micellization (ΔSmo) and standard free energy of micellization (ΔGmo), that have direct bearing on the consequences of such interactions at the molecular level have been calculated. The apparent molar volume (ϕv) and apparent molar adiabatic compressibility (ϕκ) have also been computed using densities and velocities of sound data. The above calculated parameters were found to be sensitive towards the interactions prevailing in Furosemide–SDS–DMSO-water systems.

Probing solute–solvent interactions of some bio-active solutes in aqueous barium nitrate solution on the basis of physicochemical contrivances

Apparent molar volume (ϕV), molar refraction (R), viscosity B-coefficient and adiabatic compressibility (ϕK) of some bio-active solutes such as glycine, l-alanine, and l-valine have been measured in 0.01, 0.03, 0.05moldm−3 aqueous barium nitrate solutions at 298.15K. Masson equation was employed for the limiting apparent molar volumes (ϕV0), experimental slopes (SV*) to interprete the solute–solvent and solute–solute interactions respectively. Molar refractions (R) have been calculated using the Lorentz–Lorenz equation. Jones–Dole equation was used to derive parameters A and B to interprete the interactions. Limiting apparent molar adiabatic compressibilities (ϕK0) at infinite dilution were examined from the sound speed values.

Thermodynamics and micellization of cetyltrimethyl ammonium bromide in the presence of lysozyme

To study the structural changes in lysozyme (cationic protein) on the addition of N-cetyl-N,N,N-trimethyl ammonium bromide (CTAB) and to understand the mechanism underlying aggregation of resulting protein–surfactant complex, surface tension, density and sound velocity measurements of lysozyme–CTAB solutions were carried out over a temperature range of 25–40°C. The critical micelle concentration (cmc) of CTAB has been calculated from surface tension measurements and is found to increase with increase in lysozyme concentration as well as with temperature. Surface tension data have been further used to calculate the interfacial parameters; maximum surface excess concentration (Γmax), minimum area per molecule (Amin), standard free energy of adsorption (ΔGoad), surface pressure at cmc (Πcmc) and standard free energy of transfer (ΔGotr), that have direct bearing on the consequences of such interactions at the molecular level. The negative values of standard Gibbs energy changes indicate spontaneity of micellization. Apparent molar volume (ϕv) and apparent molar adiabatic compressibility (ϕκ) have also been calculated using density and velocity of sound. These parameters have been examined as a function of surfactant concentration, lysozyme concentration and temperature to understand the consequences of interactions between these two components. A good qualitative correlation is found to exist with regard to the surfactant–lysozyme interaction obtained from the experimental data from different techniques.

Molecular interactions of α-amino acids insight into aqueous β-cyclodextrin systems

Qualitative and quantitative analysis of molecular interaction prevailing in glycine, L-alanine, L-valine and aqueous solution of β-cyclodextrin (β-CD) have been probed by thermophysical properties. Density (ρ), viscosity (η), and ultrasonic speed (u) measurements have been reported at different temperatures. The extent of interaction (solute-solvent interaction) is expressed in terms of the limiting apparent molar volume ([Formula: see text]), viscosity B-coefficient and limiting apparent molar adiabatic compressibility ([Formula: see text]). The changes on the enthalpy ([Formula: see text]) and entropy ([Formula: see text]) of the encapsulation analysis give information about the driving forces governing the inclusion. The temperature dependence behaviour of partial molar quantities and group contributions to partial molar volumes has been determined for the amino acids. The trends in transfer volumes, [Formula: see text], have been interpreted in terms of solute-cosolute interactions based on a cosphere overlap model. The role of the solvent (aqueous solution of β-CD) and the contribution of solute-solute and solute-solvent interactions to the solution complexes have also been analyzed through the derived properties.

Thermo-acoustic investigation in alcohol–water mixtures: Impact of lipophilic antioxidant on anionic surfactant properties for potential cosmeceutical application

In this present study, the self aggregation and solution properties of sodium dodecyl sulfate (SDS) in presence of lipophilic organic molecule i.e. butylatedhydroxyanisole (BHA) has been assessed by using simple and easily controlled approach to obtain CMC values and thermo-acoustic parameters via specific conductance (κ), viscosity (η), compressibility coefficient (β), apparent molar volume (ϕv) and apparent molar adiabatic compression (ϕk) at three different temperatures (25, 30, and 35°C). Taking into account the advantages of surfactant micelles as carriers, the basic impact and association of BHA on SDS micellar system has been studied in alcohol+water mixtures. It would therefore be interesting to evaluate the type of interaction between the moieties in order to design such surfactant aided immobilized system for better inhibitory action of BHA which could prove valuable to pharmaceutical or cosmeceutical industries.

Volumetric, ultrasonic and viscometric studies of solute–solute and solute–solvent interactions of l-threonine in aqueous-sucrose solutions at different temperatures

Densities, ρ of solutions of l-threonine in aqueous-sucrose solvents 5%, 10%, 15%, and 20% of sucrose, w/w in water at T=(293.15, 298.15, 303.15, 308.15, 313.15, and 318.15)K; and ultrasonic speeds, u and viscosities, η of these solutions at 298.15, 303.15, 308.15, 313.15, and 318.15K were measured at atmospheric pressure. From these experimental results, the apparent molar volume, Vϕ, limiting apparent molar volume, Vϕ∘ and the slope, Sv, apparent molar compressibility, Ks,ϕ, limiting apparent molar compressibility, Ks,ϕ∘ and the slope, Sk, transfer volume, Vϕ,tr∘, transfer compressibility, Ks,ϕ,tr∘, limiting apparent molar expansivity, Eϕ∘, Hepler’s constant, (∂2Vϕ∘/dT2), Falkenhagen coefficient, A, Jones–Dole coefficient, B and hydration number, nH have been calculated. The results have been interpreted in terms of solute–solvent and solute–solute interactions in these systems. The Gibbs energies of activation of viscous flow per mole of solvent, Δμ1∘# and per mole of solute, Δμ2∘# were also calculated and discussed in terms of transition state theory. It has been observed that there exist strong solute–solvent interactions in these systems and these interactions increase with increase in sucrose concentration in solution.

Study of solvation consequences of α-amino acids in aqueous ionic liquid solution probed by physicochemical approach

The apparent molar volume (ϕV), viscosity B-coefficient, molal refraction (R) and adiabatic compressibility (ϕK) of glycine, l-alanine, and l-valine have been studied in 0.001, 0.003, 0.005moldm−3 aqueous tetrabutylphosphonium Tetrafluoroborate (Bu4PBF4) solutions at 298.15K from the values of density (ρ), viscosity (η), refractive index (nD) and speed of sound (u) respectively. The limiting apparent molar volumes (ϕV0), experimental slopes (SV*) are obtained from the Masson equation and have been interpreted in terms of solute–solvent and solute–solute interactions respectively. Jones–Dole equation were employed to analyze the viscosity data and the interpretation of the derived parameters A and B have also been carried out in terms of solute-solute and solute–solvent interactions in the solutions respectively. Molal refractions (R) have been determined with the help of Lorentz–Lorenz equation. Limiting apparent molar adiabatic compressibilities (ϕK0) of three amino acids at infinite dilution were evaluated and discussed.

Thermodynamic properties of aqueous solutions with citrate ions. Compressibility studies in aqueous solutions of citric acid

Sound velocities in aqueous solutions of citric acid were measured from 15°C to 50°C in 5°C intervals, within the 0.1mol·kg−1 to 5.0mol·kg−1 concentration range. These sound velocities served to evaluate the isentropic and isothermal compressibilities, the apparent molar compressibilities, the isochoric thermal pressure coefficients, changes of the cubic expansion coefficients with pressure at constant temperature, the changes of heat capacities with volume and hydration numbers of citric acid in aqueous solutions.

Micellization behavior of dodecylethyldimethylammonium bromide as a function of temperature and concentration

Micellization behavior of aqueous solutions of dodecylethyldimethylammonium bromide has been studied as a function of concentration and temperature employing densiometry, viscometry, ultrasound velocity measurements and conductometry. Density data has been used to evaluate apparent molar volumes and apparent molar expansion of surfactant monomers and micelles. Isoentropic compressibility, apparent molar isoentropic compressibility and apparent molar compression values and various acoustic interaction parameters like molar sound velocity, acoustic impedance and Wada's constant, have also been calculated using ultrasound velocity data. Conductivity measurements have been used to evaluate the degree of counterion binding. All methods yielded almost similar critical micellar concentration values. The data was used to discuss thermodynamics of micellization based on phase separation and mass action models. Micellization process of the surfactant was found to be spontaneous.

Thermodynamics of Micellization of Triton X-100 in Aqueous Glycine: Tensiometric and Ultrasonic Studies

Abstract Surface tension and compressibility behavior of p-(1,1,3,3-tetramethylbutyl) phenoxypoly(oxyethylene glycol) (Triton X-100, TX-100) in aqueous mixture of glycine (Gly) have been studied at 298.15, 303.15, 308.15, and 313.15 K below and above the micellar composition range. Critical micelle concentration, cmc, of the surfactant TX-100 was obtained by surface tension, γ, density, ρ, and ultrasonic velocity, u, measurements at different temperatures. From the surface tension data, the surface excess concentration, Γ max σ , minimum area per molecule, A min , Gibbs free energy, ΔG mic 0, enthalpy, ΔH mic 0, and entropy, ΔS mic 0 of micelle formation have been evaluated. Apparent molar adiabatic compressibility, κ ϕ , was calculated from density and ultrasonic velocity data. The values of κ ϕ and apparent molar adiabatic compressibility at infinite dilution, κ ϕ 0, in the pre-micellar region and apparent molar compressibility upon micellization, Δκ ϕ m , were obtained. The observed cmc of TX-100 in aqueous glycine is found to be smaller than its value in pure water. A comparison of Γ max σ in aqueous glycine with that in pure water suggests higher adsorption of TX-100 molecules at the air–liquid interface in the former solvent than in the latter one. This was attributed to the highly hydrophilic nature of glycine molecules, causing dehydration of the surfactant molecules, thereby, facilitating the adsorption of TX-100 molecules at the air–liquid interface in the presence of glycine than in its absence. The calculated values of the Gordon parameter, G parameter, suggest that aqueous glycine acts as a good solvent for the micellization of TX-100 amphiphiles. Negative values of ΔG mic 0 and ΔH mic 0 indicate that the process of micellization of the surfactant is spontaneous and exothermic. Moreover, higher values of − TΔS mic 0 than those of ΔH mic 0 truly endorse the view that micellization of TX-100 in aqueous glycine is primarily governed by the entropy gain due to the transfer of hydrophobic groups of the surfactant from the solvent environment to the interior of the micelle. The trends in the behavior of the compressibility parameters also endorse the micellization of TX-100 in aqueous glycine.

Study of Solvation Behavior of Some Biologically Active Compounds in Aqueous Barium Chloride Solution

The density (ρ), viscosity (η), refractive index (nD), and speed of sound (u) of glycine, l-alanine, and l-valine have been determined in different mass fractions (w1 = 0.01, 0.03, 0.05) aqueous barium chloride solutions at 298.15 K. The limiting apparent molar volumes (ϕV0), experimental slopes (SV*) have been found out from the Masson equation. A and B coefficients have been obtained from the Jones–Dole equation. The Lorentz–Lorenz equation has been employed to measure molar refractions (R). Limiting apparent molar adiabatic compressibilities (ϕK0) of the studied amino acids at infinite dilution have also been measured. These derived parameters have been used to explore solute–solute and solute–solvent interactions in the solutions.

Volumetric, Compressibility and UV Spectral Studies on Interactions of Amino Acids with Aqueous Solutions of Potassium Dihydrogen Phosphate at Different Temperatures

Densities, ρ, and speeds of sound, u, for glycine, l-alanine and l-valine have been measured in (0.2, 0.4, 0.6 and 0.8) mol · kg−1 aqueous solutions of potassium dihydrogen phosphate at temperatures T = (288.15, 293.15, 298.15, 303.15, and 308.15) K. Values of the apparent molar volumes, limiting apparent molar volumes, and transfer volumes have been calculated from the density data. The experimental speeds of sound were used to estimate apparent molar adiabatic compressibilities. The variation of these parameters with temperature is discussed in terms of the role of amino acid and salt in solute–solvent interactions. The UV–visible spectrum has also been used to analyze the results.