THE ANALYSIS OF DIELECTRIC ABSORPTION DISPERSION OF GLYCINE WATER SOLUTION (original) (raw)
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DIELECTRIC DISPERSION OF GLYCINE WATER SOLUTION ABSORPTION
The dielectric coefficients of one-molar water solution of water and glycine at temperature from 20°С up to50°С in five frequencies in centimetric range are measured. The dielectric spectra taking under consideration other frequencies given in reference are studied. It is shown that Kirkwood model in which the continuous structures of water-soluble amino-acids are accepted in the capacity of medium consisting of water and bipolar molecules (zwitter-ion) of monomer acid should be revised again.
Study of Dielectric and Thermodynamic properties of Aqueous Glycine
2022
Dielectric and thermodynamic properties of aqueous glycine having molecular weight 75.07 g/mol have been studied at different concentrations in the range 0.459 to 1.480 mol/kg in the temperature range of 298.15-278.15 K. Time Domain Reflectometery technique was used in the frequency range of 10 MHz to 30 GHz. Havriliak-Nigami equation was used to analyze the frequency dependence of the complex permittivity spectra. Two relaxation processes have been detected for studied system which requires two Debye relaxation model to describe the complex permittivity spectra * (v). The low frequency relaxation process is associated with glycine molecules called β-relaxation while the high frequency relaxation process is associated with water molecules called γ-relaxation. For β-process, relaxation time was observed to be increasing towards lower temperature and higher concentration, which is associated with the rotational motion of glycine molecules in the surrounding of water. Relaxation strength was also observed to be increasing towards low temperature and high concentration, relaxation time and relaxation strength for γprocess was found almost independent of temperature. The study also covers solvation dynamics of glycine through the observed hydration number (Nhyd) and the effective hydration number (Zib). The effective dipole moment has been obtained using Cavell equation in order to see the effect of temperature and concentrations on the dipole moment and ultimately the dielectric constant of the solute molecules. The nature of the molecular interactions in pure liquid and liquid mixtures can be well understood in terms of thermodynamic functions. Thermo dynamical parameters such as molal entropy (∆S), molal enthalpy (∆H) and molal free energy (∆F) in addition to activation entropy, enthalpy and free energies have also been calculated in order to support the obtained dielectric parameters.
A study on the dielectric properties of glycine in aqueous solution medium in the microwave frequency region (130 MHz-20 GHz) is carried out using the open-ended coaxial probe technique. Dielectric parameters such as dielectric constant, dielectric loss of various weight percentage levels of glycine in double distilled aqueous medium such as water are determined. It is observed that the real part of dielectric permittivity decreases and imaginary part of the dielectric permittivity increases with increase in the weight percentage level of glycine in water. From these parameters we calculated the relaxation time and its behaviour is analysed. Dipole moment value is calculated from the optimized geometrical structure of the glycine molecule from the AM 1 , PM 3 , and MNDO ab initio quantum mechanical calculations using the Argus Lab chemical modeling Software 2004.
Dielectric Studies of Glycine–Ethylene Glycol–Water Solutions Using Time Domain Reflectometry
Journal of Solution Chemistry, 2000
Time domain reflectometry (TDR) has been used for dielectric relaxation measurements on the glycine-ethylene glycol-water ternary system (TDR) at 25, 30, 35, and 40 • C in the frequency range from 10 MHz to 10 GHz. Glycine-ethylene glycol-water solutions are prepared with different concentrations of ethylene glycol (0, 5, 10, 15, 20, and 30%) and also for different glycine molar concentrations (0, 0.2, 0.4, 0.6, 0.8, and 1 M). The dielectric relaxation parameters are measured for aqueous glycine solutions also to compare the results with those for the glycine-ethylene glycol-water ternary system. For all the solutions considered, only one relaxation peak was observed in this frequency range. The complex permittivity spectra for the aqueous glycine solutions can be well described by the Cole-Davidson expression, whereas that for the ternary system can be well described by the Havriliak-Negami expression. The logarithm of the relaxation time log(τ ) shows a nonlinear relation with the glycine molar concentration that implies a change in the relaxation mechanism with glycine concentration. The dielectric strength ε increases with an increase in glycine molar concentration, whereas it decreases with an increase in ethylene glycol concentration.
Journal of Solution Chemistry, 2000
Dielectric relaxation measurements on water-ethanol-glycine ternary system were carried out using time domain reflectometry (TDR) at 25, 30, 35, and 40 • C in the frequency range from 10 MHz to 10 GHz. Glycine-ethanol-water solutions are prepared with different concentrations of ethanol (0, 5, 10, 15, 20, and 30%) and also for different glycine molar concentrations (0, 0.2, 0.4, 0.6, 0.8, and 1 M). The dielectric relaxation parameters are measured for aqueous glycine solutions also to compare the results with those for the glycine-ethanol-water ternary system. For all the mixtures considered, only one relaxation peak was observed in this frequency range. All the mixtures display a Cole-Davidson dispersion. The relaxation peaks shift to lower frequency with an increase in glycine concentration and also with ethanol concentration. The logarithm of the relaxation time log(τ ) shows a nonlinear relation with glycine concentration which implies a change of relaxation mechanism with glycine concentration. The dielectric strength ε for these mixtures shows a nearly linear relation with glycine molar concentration.
Dielectric Study of Aqueous Solutions of Alanine and Phenylalanine
Journal- Chinese Chemical Society Taipei
Dielectric relaxation measurements on aqueous solutions of alanine and phenylalanine were carried out using time domain reflectometry (TDR) at 25, 30, 35, and 40 °C in the frequency range from 10 MHz to 20 GHz. Aqueous solutions of alanine and phenylalanine are prepared for five different molar concentrations of the respective amino acid. For all the solutions considered, only one relaxation peak was observed in this frequency range. The relaxation peaks shift to lower frequency with an increase in alanine and phenylalanine molar concentration. The molar enthalpy of activation and molar entropy of activation show endothermic interactions.
Nano Biomedicine and Engineering, 2020
Complex permittivity in terms of dielectric constant (ε') and dielectric loss (ε") of medicinal compound paracetamol in dimethyl sulfoxide (DMSO) solvent was determined with different weight fractions at microwave frequency 9.85 GHz at constant temperature 27 °C. The information on dielectric properties is related to the properties of the substance for preparation of granules while making dosage forms like tablets and capsules. Refractive index (nD), dielectricconstant (ε') and dielectric loss (ε") were used for the measurement of relaxation time (τ). The viscosity (η) and density of paracetamol in DMSO were determined using a conventional Ostwald’s viscometer and specific gravity bottle respectively. The aim of the present work was to study the dielectric properties of the drugs and attempted to determine their correlations with density and viscosity to understand the behavior of the dielectric properties under different conditions like a concentration in solution...
The complex spectra of glycolic acid (GA) and water mixture have been measured by time domain reflectometry (TDR) in the frequency range 10 MHz to 30 GHz at various temperatures for entire concentration. Dielectric relaxation time (τ), static dielectric constant (ɛ 0) and dielectric permittivity at low frequency (ɛʹ) and at optical frequency (ɛʺ) have been determined from measured complex spectra (ɛ*) using non-linear square fit method. Conductivity, Kirkwood and effective Kirkwood correlation factor of mixture calculated from the determined dielectric parameters have been used to find the alignment of dipoles between molecules. Thermodynamic parameters enthalpy, entropy and Gibb's free energy have been determined which enable the direction of reaction. Excess permittivity of glycolic acid-water mixture has also been determined which confirms the molecular interaction. Macroscopic parameters such as density and viscosity of mixture have been determined at room temperature. FTIR ...
Dielectric properties of glycerol/water mixtures at temperatures between 10 and 50°C
The Journal of Chemical Physics, 2006
At six temperatures T between 10 and 50°C and at mole fractions xg of glycerol (0<xg⩽0.9) the complex (electric) permittivity ϵ(ν) of glycerol/water mixtures has been measured as a function of frequency ν between 1MHz and 40GHz. The spectra of the glycerol/water mixtures can be well represented by a Davidson-Cole [J. Chem. Phys. 18, 1417 (1950)] relaxation function that reveals an unsymmetric relaxation time distribution. The effective dipole orientation correlation factor derived from the static permittivity displays an unspectacular behavior upon mixture composition. The dielectric relaxation time reveals a simple relation to the shear viscosity of the mixtures, but both quantities are not proportional to one another. The relaxation times at high temperatures nicely complement previously determined low temperature data, following a Vogel-Fulcher-Tammann-Hesse [Z. Phys. 22, 645 (1925); J. Am. Chem. Ceram. Soc. 8, 339 (1923); Z. Anorg. Allg. Chem. 156, 245 (1926)] (VFTH) temperat...
2022
Dielectric relaxation measurements of amino acid (L-alanine) in water solution were carried out using time domain reflectometry at 25C to -5C in the frequency range between 10 MHz to 30 GHz. The dielectric parameters i.e. static dielectric constant and relaxation time, were obtained from the complex permittivity spectra using a nonlinear least square fit method. From the values of the relaxation time, the thermodynamic parameters are determined. The Kirkwood correlation factor was calculated from the static permittivity. The dielectric relaxation parameters increase with an increase in concentration (mM) of amino acid (L-alanine) due to the structure of hydrogen bond groups by the amino acid (L-alanine) molecules in the aqueous solution. The relaxation peak shifted to lower frequency with an increase in molar concentration of amino acid.