Effect of KCl and KNO3 on Partial Molal Volumes and Partial Molal Compressibilities of Some Amino Acids at Different Temperatures

Abstract

Density (ρ) and ultrasonic velocity (u) values of amino acids l-alanine, l-proline, l-valine, and l-leucine in 2 M aqueous KCl and 2 M aqueous KNO 3 solutions have been measured as a function of amino acid concentration at different temperatures (298.15 K, 303.15 K, 308.15 K, 313.15 K, 318.15 K, and 323.15 K). Using the ρ and u data, partial molal volume (φ o v ) and partial molal isentropic compressibility (φ o k ) values have been computed. The increase in partial molal volume with temperature has been attributed to the volume expansion of hydrated zwitterions. The φ o v and φ o k values of l-alanine, l-proline, l-valine, and l-leucine in 2 M aqueous KCl and KNO 3 solutions have been found to be larger than the corresponding values in water. The larger partial molal volumes of l-alanine, l-proline, l-valine, and l-leucine in 2 M aqueous KCl and KNO 3 solutions have been ascribed to the formation of 'zwitterion-K + /Cl − /NO 3 − ' and 'K + /Cl − /NO 3 − -water dipole' aggregates in solutions. The formation of these entities in solutions causes the release of water associated with zwitterions to the bulk water. The larger partial molal compressibilities of l-alanine-/l-proline-/l-valine-/l-leucine-2 M aqueous KCl/KNO 3 solutions than the corresponding values in water have been attributed to the formation of 'zwitterion-ion' and 'ion-water dipole' incompressible entities in solutions.

Experimental and Theoretical Exploration of Volumetric Properties of Aminobutyric Acid and l-Valine in the Electrolytic Environment at T = 283.15 to 318.15 K and Pressure P = 0.1 MPa

“…Therefore, as the amino acids are present in the zwitterionic forms (neutral pH), the solute–solvent interactions are favored by the electrostriction of water occurring at the end of zwitterion groups, originating a local increase in the density of the solvent with more molecules packed around each ion. Therefore, Na + –S 2 O 3 2– and −COO – –NH 3 + interactions affect the hydration spheres of the charged end groups of zwitterions, causing an overlap of hydration co-spheres and the resulting volume changes in aqueous salt solutions. , …”

Viscosity studies of (l-alanine-, l-proline, l-valine, l-leucine+aqueous KCl/KNO3) solutions at different temperatures

“…The viscosity values of water at different temperatures were taken from the literature for calibration purpose [26]. The densities required for the calculation of viscosity values of the solutions were taken from our earlier studies [23,24]. A thermostatted paraffin bath used for measurements of viscosity values was maintained at a desired temperature (±0.01 K) for about 30 min prior to recording of readings at each temperature of study.…”

“…The present study is a continuation of our research program on the thermodynamic studies of amino acid-aqueous salt solution systems [21][22][23][24][25]. This investigation focuses on the measurements of viscosity coefficients of (L-alanine-, L-proline, L-valine, L-leucine + 2.0 M aqueous KCl/KNO 3 ) solutions as functions of amino acid concentration and temperature at (298.…”

A Review on General Properties and Applications of Ionic Liquids

“…Each element of material to go back to its original position after movement an expandable substance which as restoring force that tends to restore. To study the physicochemical properties of the liquid mixtures, liquids, polymeric and electrolytic solutions is the main significant and generally accepted technique [34][35][36][37][38][39] .…”