Mole Of Solvent Research Articles

Optimization of White Tea Flavanol Extraction Process by the Ultrasonic‐Assisted Deep Eutectic Solvent Method and Determination of the Antioxidant and Antibacterial Activity

ABSTRACTFlavanols have a variety of health benefits and biological activities and become the hotspot of the food development and research. In this research, flavanols were extracted from white tea by ultrasonic‐assisted deep eutectic solvent (DES) method. High‐performance liquid chromatography was used to determine the content of flavanols. The influence of four factors on the flavanol extraction yield was analyzed by single factor experiments, including deep eutectic solvent mole ratio (the mole of hydrogen bond acceptors: the mole of hydrogen bond donors), solid–liquid ratio (white tea sample weight/g: the volume of DES/mL), extraction time and extraction temperature. On the basis of single factor experiments, the factors which had significant effects on the flavanol extraction yield were further optimized by the response surface test. The results showed that the optimized extraction conditions were as follows: the mole ratio of DES 1: 4 (choline chloride: 1,2‐propanediol), the solid–liquid ratio 1:30, the extraction temperature 56°C, the extraction time 53 min, and the ultrasonic power 341 W. Under the above parameters, the extraction yield of white tea flavanols was 9.63 mg/g. After purification with macroporous resin, antioxidation and antibacterial experiments were carried out. The results showed that the antioxidant and antibacterial effects of white tea flavanols were remarkable. The antibacterial effects performed best on Escherichia coli, followed by Bacillus subtilis and Staphylococcus aureus. The maximum diameter of the antibacterial zone on Escherichia coli was 0.95 ± 0.11 mm. The best radical scavenging rates of OH, ABTS+ and DPPH were 97.1%, 97.5%, and 88.4%, respectively, when the flavanol concentration was 9.5 mg/mL. The conclusions of this research can provide theoretical foundation for the further study of white tea flavanols.

A thermodynamic approach to analyzing relative permittivity and solvent mole fraction models, and application to SN1 reactions.

The standard methods for analyzing solvent effects on chemical reactions largely include linear free energy relations that relate kinetic and spectroscopic terms to solvent interactive parameters. The number of these parameters has grown over the years in order to make linear free energy techniques more accurate and cover a wider range of reaction systems. However, even with the myriad of parameters, the details of specific reaction systems make the application of these techniques sometimes unreliable. On the other hand, a thermodynamic approach provides a more precise analysis, and has proven particularly useful for reactions in multi-component solvent systems. In this article we present the mathematical formalism for relating the activation free energy to the bulk thermodynamic properties for a binary (cosolvent) system. We then use this thermodynamic approach, coupled with selected solvent models, to analyze the hydrolysis rates of tert-butyl chloride in the acetonitrile/water solvent system under iso-mole fraction, isodielectric, and isothermal conditions. These analyses allow us to differentiate and quantify bulk electrostatic effects and the effects of close-range solute-solvent interactions.

Investigation of intermolecular interactions of l-Valine and l-Phenylalanine with muscle relaxant drug mephenesin molecule prevalent in aqueous solution by various physico-chemical methods at T=298.15K–313.15K

A complete chemical analysis of significant intermolecular interactions of l-Valine (L-Val) and l-Phenylalanine (L-Phe) with Mephenesin (MEPN) molecules in aqueous solution has been studied by different physicochemical methodologies at various temperatures (T = 298.15 K–313.15 K at an interval of 5 K) and concentrations (0.001 mol kg−1, 0.003 mol kg−1, 0.005 mol kg−1) of aqueous MEPN solution. The limiting apparent molar volume (φV0) and experimental slope (SV*) values are found from the equation of Masson, viscosity A and B-coefficient determined using the equation of Jones-Doles, molar refraction (RM) and limiting molar refraction (RM0) derived by the Lorentz-Lorenz equation, express that in our experimental solution of amino acids (AAs) in aqueous MEPN, the solute-solvent interaction predominates over the solute-solute and solvent-solvent interactions for these ternary solutions. These are also justified by the measurement of various thermodynamic parameters, free energy of activation of viscous flow per mole of solvent(Δμ1°#) and solute (Δμ2°#), activation of viscous flow of enthalpies (ΔH°#) and entropies (ΔS°#). The characteristics of structure-breaking of solutes in the aqueous drug solution have been identified by Hepler's method and dB/dT value. The spectroscopic methods like UV–visible and proton-NMR studies help to explicate the strong AA-MEPN interactions in the solution phase and obtain a good correlation with theoretical studies. Theoretical investigations are checked to authenticate the experimental observations and according to both studies, L-Phe-MEPN interaction is greater than L-Val-MEPN interaction. The experimental and correlated research data are useful for the development of model combinations of AAs with drug molecules in pharmaceutical and medicinal chemistry.

Synthesis of silver nanoparticles for use in conductive inks by chemical reduction method

In this study, the chemical reduction method was applied to synthesize silver nanoparticles used to prepare conductive inks. The two variables of polyvinylpyrrolidone (PVP)-stabilized mole in the 0.01–0.03 mol range and hydrazine reducing mole in the 0.1–0.5 mol range, along with constants such as precursor mole (silver nitrate), complexing mole (ethylene diamine) and solvent mole (water), were used. Nine random samples proposed by the Design Expert software were examined and studied. X-ray diffraction (XRD) patterns, field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM) and dynamic light scattering (DLS) were then used to characterize and evaluate the synthesized nanoparticles. According to the results obtained by XRD, FE-SEM and TEM analyses, the sample with 0.025 mol and 0.3 mol PVP had the minimum size of silver nanoparticles, which was around 20 nm, so it was chosen as the optimal sample for further research. The conductive ink was also prepared with the optimal sample of silver nanoparticles in 40% by weight and then characterized and evaluated by applying ultraviolet–visible (UV–Vis), simultaneous thermal analysis (STA), FE-SEM and electrical conductivity analysis. Finally, conductive ink was applied to polyethylene terephthalate (PET) and acrylonitrile butadiene styrene (ABS) substrates. The surface electrical resistance of conductive ink on PET and ABS substrates was then measured at about 6.4 Ω and 2.2 Ω, respectively.

Volumetric and transport properties of switchable-hydrophilicity solvent systems: N,N-Dimethylbutylamine, water and carbon dioxide

Switchable-hydrophilicity solvents (SHSs) are an emerging class of solvents with switchable phase behavior. They can be used as a substitute for volatile solvents and can be removed from organic products without distillation. However, the detailed physical properties data of SHSs are still very scarce in the literature. In this work, the experimental values densities, dynamic viscosities, refractive indices as well as conductivities of switchable hydrophilicity solvent (SHS)systems (N,N-Dimethylbutylamine (DMBA), water, and carbon dioxide) are investigated at temperatures (283.15, 288.15, 293.15, 298.15, 303.15 and 308.15) K and at atmospheric pressure. VLE of the CO2 loaded DMBA solutions are measured at 298.15 K over the partial pressure range of carbon dioxide from 17.0 to 98.0 kPa. Density data have been used to calculate the apparent molar volumes (Vϕ), limiting apparent molar volumes (Vϕ0) and limiting partial molar expansivity of solute (Eϕ0). The Jones-Dole coefficients B, the Gibbs free energies of activation of viscous flow per mole of solvent (Δμ10≠) and per mole of solute (Δμ20≠), entropies (ΔS20≠) and enthalpies (ΔH20≠) of activation of viscous flow were calculated from experimental viscosity data and discussed in terms of transition state theory. The Walden's product was calculated from the conductance and dynamic viscosity data. The results are valuable sources of information on the design and development of SHSs for novel industrial applications.

Transport behaviour and FT-IR study of some protein model compounds + 1-butyl-3-methylimidazolium bromide mixtures at different temperatures

Low volatility, low flammability, thermal stability, and biocompatibility contributed to ILs' popularity as eco-friendly media. Therefore, ILs can provide some insights regarding the ability of proteins towards stability. The objective of these studies was to gain new insights into the ability of biomolecules to interact with one another, which is essential for comprehending the behaviour of proteins in solution. Several other properties, including viscosity B-coefficients, temperature coefficient (dB/dT), activation free energy of viscous flow per mole of solvent (Δμ1o#) and solute (Δμ2o#), thermodynamic activation parameter, ΔG2o1→1′, viscometric pair (ηAB) and triplet (ηABB) interaction coefficients along with activation free energy of enthalpy (ΔH2o#) and entropy (ΔS2o#) were obtained by the use of appropriate models. Solvation number (Sn) and hydration number (Nh) were also calculated along with group conributions. Fourier transform infrared spectroscopy (FTIR) has been recorded to perceive interactions among these ternary systems. The current study contributes to understanding the structure and molecular interactions between ILs, amino acids/proteins, and industrial processes.

Performance of Some Novel Mixed Solvents as Entrainers for Separation of Water and Acetonitrile

Performance of some novel mixed solvents as entrainers was tested for acetonitrile dehydration by extractive distillation. The mixed solvents are composed of ethylene glycol (EG) and choline chloride (ChCl) (EG + ChCl 8:1, EG + ChCl 4:1, EG + ChCl 2:1, and EG + ChCl 4:3), ethylene glycol (EG) and glycerol (EG + glycerol 1:1, EG + glycerol 1:2, EG + glycerol 1:4, and EG + glycerol 1:6), and dimethyl sulfoxide (DMSO) and ChCl (DMSO + ChCl 14:1). Isobaric vapor–liquid equilibrium (VLE) data were measured at 101.3 kPa and at a solvent-free acetonitrile mole fraction of 0.95 for the quaternary systems of water + acetonitrile + EG + ChCl, water + acetonitrile + EG + glycerol, and water + acetonitrile + DMSO + ChCl and for the ternary system of water + acetonitrile + DMSO. The NRTL equation was used for the correlation of the experimental VLE data. For all the three quaternary systems and one ternary system, the mean absolute deviations of equilibrium temperature were no more than 0.33 K, and the mean absolute deviations of water and acetonitrile vapor phase mole fractions were no more than 0.0026 and 0.0047, respectively. The mixed solvent EG + ChCl 4:3, which is also a deep eutectic solvent, showed favorable solvent performance. The azeotrope of water + acetonitrile can be removed at a solvent mass fraction of 0.212 or a solvent mole fraction of 0.104. This amount is less than that of EG (0.367 in mass fraction and 0.227 in mole fraction), EG + glycerol 1:6 (0.341 in mass fraction and 0.195 in mole fraction), and DMSO + ChCl 14:1 (0.266 in mass fraction and 0.153 in mole fraction).

Direct Correlation of the Salt-Reduced Diffusivities of Organic Solvents with the Solvent's Mole Fraction.

Lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) in organic solvents (especially propylene carbonate) has demonstrated extraordinary pseudocapacitive performance as an electrolyte in the supercapacitor configuration ( Nat. Energy 2019, 4, 241-248). However, the influence of the solvated ions on the diffusivity of the solvent molecules is yet to be understood. We examine the impact of LiTFSI on the diffusivity in five organic solvents: acetonitrile (ACN), tetrahydrofuran (THF), methanol (MeOH), dimethyl sulfoxide (DMSO), and propylene carbonate (PC) using a combination of neutron scattering, conductivity measurements, and molecular dynamics simulations. The extent of the diffusivity reduction in the concentration regime of ≤1 M directly correlates with the solvent mole fraction at which the solvation shells around Li+ ions are of similar size in all the solvents, resulting in a universal ∼50% reduction in the solvent diffusivity. These results provide guidance for formulation of the new electrolytes to enhance the performance of energy storage devices.

The Influence of Electrolyte Type on Kinetics of Redox Processes in the Polymer Films of Ni(II) Salen-Type Complexes.

Electrodes modified with polymers derived from the complexes [Ni(salcn)], [Ni(salcn(Me))] and [Ni(salcn(Bu))] were obtained in order to study the kinetics of electrode processes occurring in polymer films, depending on the thickness of the films, the type of electrolyte and the solvent. FTIR and EQCM methods were used to determine the type of mass transported into polymer films during anode processes and the number of moles of ions and solvent. The rate of charge transport through films was determined by the cyclic voltammetry method, by the quantity cD1/2. It was shown that the charge transport was determined by the transport of anions. The kinetics were most efficient for poly[Ni(salcn(Bu))] modified electrodes, obtained from TBAPF6 and working in TBAClO4 and TBABF4. It was also shown that a solvent with a higher DN value and lower viscosity (MeCN) facilitated the transport of the charge through polymer films.

Synthesis and Characterization of La-Doped Hafnium Oxide Thin Films by Sol–Gel Method

In this article, the effect of lanthanum-doped HfO2 structure is investigated in order to verify the ferroelectric property as a candidate for the next generation of FeRAM. The xLa-doped HfO2 thin films with x equals to 0.0, 0.2, 0.4, 0.5, 0.6, and 0.8 were prepared by sol–gel method. Hafnium chloride and lanthanum chloride were employed as starting materials which were initially dissolved in ethanol and ethylene glycol, respectively. Diethanolamine was applied as a stabilizer. The ratio between moles of metals, solvent, and stabilizer was initially varied to obtain gel and it was found that 1:80:4 is the most suitable ratio. After spin coated on a substrate (Si), the gel of La-doped HfO2 was annealed to make thin films at 300–1000 °C under atmosphere. Phase formation and microstructure were characterized using Grazing Incidence X-ray diffraction and Field Emission Scanning Electron Microscope (FE-SEM). XRD results showed that a monoclinic phase of HfO2 was found when the films were annealed at 600 °C for 3 and 5 h. Homogenous surfaces were observed in SEM images. Distribution of Hf and La existed on the surface of all samples were also revealed by EDS. The experimental results showed that La-doped HfO2 thin films were successfully synthesized using the sol–gel method. Mole ratios and annealing temperature played a significant role in phase formation and homogeneity of La-doped HfO2 thin films.

Ultrasonic characterisation of the binary mixture of 2,3-dichloroaniline with methanol and ethanol

ABSTRACT The present work focuses on the ultrasonic characterisation of the binary mixture having constituent liquids, 2,3-dichloroaniline and methanol/ethanol, by measuring their density, viscosity, ultrasonic velocity and estimating thermo-physical parameters at 25°C. The density, viscosity, ultrasonic velocity, acoustic impedance and relative association decay, while compressibility and free length increase with the increase in mole fraction of solvent in the present binary mixture. An anomalous change is received in excess molar volume, free volume, thermal relaxation time, Gibbs free energy and ultrasonic absorption up to 80% solvent mole fraction. The analysis reveals that the binary mixture 2,3-DCA+ methanol has a good intermolecular interaction strength, and is more structural and less corrosive than 2,3-DCA+ ethanol due to the formation of excess hydrogen bonding at 70% solvent mole fraction.

The significance of operating parameters on electromagnetic-solvent bitumen recovery process

Current thermal bitumen recovery processes are highly vulnerable to the low oil price environments. Solvents-aided processes could be a promising option over Steam Assisted Gravity Drainage (SAGD), with the potential for lowered initial capital investment and reduced operating costs. Enhanced Solvent Extraction Incorporating Electromagnetic Heating (ESEIEH®) technology is a novel process where electromagnetic waves and hydrocarbon solvents are employed for bitumen recovery.This study examines the significance of operating parameters on the electromagnetic-solvent process when the injected solvent is either pure propane or pure butane. The effect of several parameters, including operating pressure and applied power on various response surface models, were examined using Design of Experiment and multivariate regression analysis. Results show that the operating pressure is the main governing factor for the selection of the solvent type, while other parameters such as applied power are less significant. Generally, it is recommended to operate the process at native reservoir pressure to minimize the risk of loss of expensive solvents into the thief zones.Lack of reservoir containment (leakiness) is another important factor in the process design, especially when prescribing an operating pressure regime considerably different than that of the surrounding impairments. Due to a wide variation of the in-situ bitumen viscosity in different oil sands reservoirs, each bitumen type requires a different solvent mole fraction to mobilize the bitumen. For the type of bitumen used in this study, the optimum pressure range for butane was found to be around 800–1000 kPa, and for propane injection, around 2400–2600 kPa.

Probing interactions and hydration behaviour of drug sodium salicylate in aqueous solutions of D-xylose/L-arabinose: Volumetric, acoustic and viscometric approaches

The solute–solute and solute–solvent interactions of drug sodium salicylate in aqueous-carbohydrate solutions are investigated using experimentally measured densities, ρ, ultrasonic speeds, u and viscosities, η of the drug sodium salicylate in water and in aqueous−D-xylose/L-arabinose (5% and 10% D-xylose/L-arabinose in water, w/w) solvents at temperatures (293.15, 298.15, 303.15, 308.15, 313.15 and 318.15) K and at atmospheric pressure. The ρ, u and η data were used to calculate the apparent molar volumes, Vϕ, limiting apparent molar volumes, Vϕ°, limiting apparent molar expansibilities, Eϕ°, apparent molar compressibilities, Ks,ϕ, limiting apparent molar compressibilities, Ks,ϕ° along with the transfer volumes, Vϕ,tr° and transfer compressibilities, Ks,ϕ,tr°. Furthermore, Falkenhagen coefficient A, Jones-Dole coefficient B, free energy of activation of viscous flow per mole of solvent, Δμ1°# and per mole of solute, Δμ2°#, enthalpies, ΔH°# and entropies, ΔS°#of activation of viscous flow were obtained from the viscosity data. The observed trends in these properties as function of temperature and composition were analysed in terms of molecular interactions amongst the solute and solvent molecules. The results are discussed in terms of hydrophilic-hydrophilic and hydrophilic-hydrophobic interactions in these systems along with the structure breaking/making ability of the drug.

Molecular interactions studies of doxycycline hyclate in water, aqueous L-phenylalanine and glycyl glycine at different temperatures by using volumetric, ultrasonic and viscometric parameters

The density, sound velocity and viscosity of doxycycline hyclate in water, aqueous solution of L-phenylalanine and aqueous solution of glycyl glycine have been determined at different temperatures (305.15, 310.15, 315.15 and 320.15) K. The calculated values of partial molar volume (V_ϕ^o), standard partial molar volume of transfer (〖Δ_tr V〗_ϕ^o), partial molar adiabatic compressibility (κ_(ϕ,s)^o) and partial molar adiabatic compressibility of transfer (〖Δ_tr κ〗_(ϕ,s)^o) for doxycycline hyclate in water, aqueous solution of L-phenylalanine and aqueous solution of glycyl glycine infer the dominance of ion-hydrophilic interactions over hydrophobic-hydrophobic interactions. The Jones-Dole viscosity B-coefficient, viscosity B-coefficient of transfer (ΔtrB), free energy of activation of viscous flow per mole of pure solvent (〖Δμ〗_1^(o*)) and solute (〖Δμ〗_2^(o*) ), respectively, activation entropy (〖ΔS〗_2^(o*)) and activation enthalpy (〖ΔH〗_2^(o*)) of doxycycline hyclate in water, aqueous solution of L-phenylalanine and aqueous solution of glycyl glycine also have been calculated using viscosity data. The structure making and breaking behaviour of doxycycline hyclate in water, aqueous solution of L-phenylalanine and aqueous solution of glycyl glycine are obtained from the values of Hepler’s constant i.e.((δ^2 V_ϕ^o)/(δT^2 )) and (dB/dT). The presence and absence of caging effect has been studied with the help of partial molar adiabatic expansibility (E_ϕ^o). The isobaric thermal expansion coefficient (α^o= (E_ϕ^o)/(V_ϕ^o )), intermolecular free length and acoustic impedance for doxycycline hyclate in water, aqueous solution of L-phenylalanine and aqueous solution of glycyl glycine also have been determined.

Volumetric and transport properties of ternary solutions of l-serine and l-valine in aqueous NaCl solutions in the temperature range (293.15–323.15) K

In this paper we report new density and viscosity data of l-serine and l-valine in aqueous NaCl solutions as a function of amino acids molality at fixed salt concentration (0.1, 0.2, 0.5, 0.7 and 1.0 mol·kg−1) and temperature T = (293.15, 298.15, 303.15, 308.15, 313.15, 318.15 and 323.15) K at atmospheric pressure of p = 0.1 MPa. From density, some derived properties such as the apparent molar volume, Vϕ, limiting partial molar volume, Vϕ0, and expansibility, Eϕ0, standard molar volume of transfer, ΔVϕ0, and hydration number, nH, were calculated and discussed in terms of solute–solvent interactions and structural effects. The Jones–Dole equation and transition state treatment were used to obtain the viscosity B coefficient, free energy of activation of viscous flow per mole of solvent, Δμ10#, and per mole of solute, Δμ20#, entropies, ΔS20#, and enthalpies, ΔH20#, of activation of viscous flow for amino acids. All the activation parameters were discussed in terms of transition state theory. The co-sphere overlap model was used to interpret the results. The structure making/breaking ability of the amino acids in solutions was also discussed.

Insight into solute-solute and solute-solvent interactions of l-proline in aqueous-D-xylose/L-arabinose solutions by using physicochemical methods at temperatures from 293.15 to 318.15 K

The interactions of l-proline with carbohydrates are investigated by using volumetric, viscometric and acoustic properties. The measurements of the densities, ρ, ultrasonic speeds, u and viscosities, η of the l-proline in water and in aqueous-D-xylose/L-arabinose (2.5% and 5% D-xylose/L-arabinose in water) solvents were carried out at temperatures (293.15–318.15) K and at atmospheric pressure of 101 kPa by using digital vibrating tube density and sound analyzer and microviscometer. The experimental data have been used to evaluate the apparent molar volumes, Vϕ, limiting apparent molar volumes, Vϕ°, apparent molar compressibilities, Ks, ϕ, limiting apparent molar compressibilities, Ks,ϕ°, transfer volumes, Vϕ,tr° and transfer compressibilities, Ks,ϕ,tr°. The viscosity A and B coefficients, Gibbs free energies of activation of viscous flow per mole of solvent, Δμ1°# and of solute, Δμ2°#, enthalpies, ΔH∘# and entropies, ΔS∘# of viscous flow, were obtained using the viscosity data. The effect of concentration, temperature and solute structure were discussed in terms of solute-solvent and solute-solute interactions prevailing in these systems. The structure making/breaking ability of l-proline is examined in from the sign of temperature derivative of B-coefficient, dB/dT. The thermodynamic parameters of viscous flow for the solutions are also calculated and discussed using transition state theory.

Studies on Volumetric and Viscometric Properties of L-Glutamic Acid in Aqueous Solution of Glucose over a Range of Temperatures (298K to 323K)

In this work, volumetric and viscometric properties of L-glutamic acid in water and aqueous glucose solutions (5%, 10%, 15%, and 20% of glucose, w/w in water) have been measured as a function of molal concentration (0.02 mol.kg-1 to 0.16 mol.kg-1) of L-glutamic acid at different temperatures T= (293.15, 303.15, 308.15, 313.15 and 323.15) K. By using experimental densities (ρ) and viscosities (η) data, apparent molar volume (φv), experimental slope (Sv), limiting apparent molar volume (φv0), limiting apparent molar volume transfer (Δφv0)tra, limiting apparent molar expansibilities (Eφ0), Hepler’s constant (δEφ0/δT)p, Falkenhagen coefficient A, and Jones-Dole coefficient B have been computed. Gibbs free energies of activation of viscous flow per mole of solvent (μ_1^(0#)) and per mole of solute 〖(μ〗_2^(0#)), hydration number (Hn) is also calculated. The results are discussed based on solute-solute and solute-solvent interactions in these systems. From the results, it is observed that there exists a structure making propensity of L-glutamic acid in water and in the different mass fraction of aqueous glucose solutions, which increases with the increase of glucose concentrations.

Volumetric and viscometric properties of ternary solution of (piperazine +2-Amino-2-methyl-1-propanol + H2O) at T = (303.15–343.15) K

The densities and viscosities of ternary solution of piperazine (PZ) + 2-Amino-2-methyl-1-propanol (AMP) + H2O were measured at P = 101 kPa and T = (303.15–343.15) K. The effects of temperature and concentration on the density and viscosity of ternary solution were investigated. The apparent molar volume (Vφ), the limiting partial molar volume (Vφ0), viscosity B-coefficient, Helper's constant and the free energies of activation per mole of solvent (Δμ10≠) and solute (Δμ20≠) were calculated from the density and viscosity, respectively. The solute-solute and solvent-solute interactions were analyzed from the volumetric and viscometric properties. The results show that the PZ has a destructive effect on the structure of mixed solvent.

Molecular Interactions of Non-Steroid Anti-Inflammatory Drug Dolonex in Aqueous Solutions of L-Alanine/L-Valine at Different Temperatures: Viscometric Approach

The viscosities of aqueous solutions of L-alanine and L-valine with non-steroid anti-inflammatory drug dolonex (0.020, 0.040, 0.060 mol kg–1) have been measured at different temperatures (293.15–313.15 K) and at atmospheric pressure. On the basis of experimental results Jones–Dole coefficient-B, viscosity B-coefficient of transfer, activation parameters i.e., free energy of activation of viscous flow per mole of solvent $$\Delta \mu _{2}^{{^\circ \# }}$$ and per mole of solute $$\Delta \mu _{1}^{{^\circ \# }}$$ were determined. The obtained results were discussed in terms of solute–solvent interactions in these solutions. Moreover, structure breaker tendency of solute molecules were obtained by measuring temperature derivative of viscosity B-coefficient.

Viscometric and spectroscopic studies on interactions of glycine with aqueous buffer solutions

Abstract To study the solvation and hydration behavior of glycine, viscosity measurements have been carried out for glycine in water of pH = (1.00, 7.40 and 14.00) and in different concentrations (0.1, 0.5 and 1.0) M of aqueous potassium/sodium phosphate buffer (KPB/NaPB) solutions of pH = (1.00, 7.40 and 14.00) at different temperatures, T = (298.15, 308.15, 310.15 and 318.15) K. Viscosity B-coefficients for glycine in water and in aqueous buffer solutions have been obtained at different temperatures using Jones-Dole equation. Viscosity B-coefficients of transfer (∆trB) values have been calculated from viscosity B-coefficient data. Both positive and negative viscosity B-coefficients of transfer have been observed in the studied system. The Gibbs energies of activation for viscous flow per mole of solvent (∆μ1o) and per mole of solute (∆μ2o) have been calculated and discussed in terms of transition state theory. Solvation (Sn) and hydration (nH) numbers have also been calculated from these data. The results have been discussed in terms of solute-solvent and solute-solute interactions in these systems. The structure-making/breaking ability of glycine has been discussed in terms of the sign of dB/dT. UV absorption spectra for glycine in aqueous KPB solutions has been recorded. All the viscometric and spectroscopic parameters have been used to explore various interactions that may arise in presently investigated ternary solutions.