Shilpa A. Mirikar; Pravina P. Pawar; Govind K. Bichile

Abstract

"Ultrasonic Velocity, Density and Viscosity Measurement of Amino Acid in Aqueous Electrolytic Solutions at 308.15K"

Objective: The objective of the study was molecular interactions in the liquid mixtures is very much important to study the structural properties of molecules and great deal of interest in investigating the solute-solute, solute-solvent and solvent-solvent interaction.
Methods: With a view to understand the molecular interaction in electrolyte with amino acid based liquid system There are many approaches and spectroscopic techniques used to determine the structure-function relationship of bio-molecules. The methods are often interconnected and therefore providing a complementary information about the studied biomolecular structure. Among the techniques used, the measurement of ultrasonic velocity has been adequately employed in understanding the nature of molecular systems and physico–chemical behavior in liquid mixtures. The ultrasonic velocity (U) in liquid and liquids mixtures have been measured using an ultrasonic interferometer (Mittal type, Model F-81) working at 2 MHz frequency with an accuracy of ± 0.1 ms^-1. The density of pure liquids and liquid mixtures was determined using specific gravity bottle by relative measurement method with accuracy of ±0.1Kgm^-3 .An Ostwald’s viscometer was used for the viscosity measurement of pure liquids and liquid mixtures with an accuracy of ±0.0001NSm^-2. The temperature around the viscometer and specific gravity bottle was maintained within ±0.1K in an electronically operated constant temperature water bath. Results: Density and ultrasonic velocity provide interesting information regarding the ion-ion ion-solvent and solvent-solvent interactions and also on structural effects of solute and solvent in solutions. A systematic study using ultrasonic velocity (u), density (ρ) and viscosity (η) measurements as a function of mole fraction has been carried out. The temperature dependence of these quantities has also been investigated at 308.15K using this experimental data, thermodynamic parameters such as the adiabatic compressibility (βa), intermolecular free length (L_f), acoustic impedance (z) and relative association (RA) of amino acids in aqueous solution of electrolyte at 308.15K temperature and at different concentrations of solutes have been studied and have been estimated using the standard relations. The results have been analyzed on the basis of variations of thermodynamic parameters. The presence of strong interactions is noticed in the ternary system.
Conclusion: At various concentrations and temperature in valine-based system, shows the nonlinear increase or decrease behavior. The non linearity confirms the presence of solute-solvent, ion-ion, dipole-dipole, ion-solvent interactions. The observed molecular interaction, complex formation, hydrogen bond formation are responsible for the heteromolecular interaction in the liquid mixture. This provides useful information about inter and intra molecular interactions of liquid systems.