Journal of Chemical Thermodynamics, Vol.77, 116-122, 2014
Densities, viscosities, refractive indices, and electrical conductivities of aqueous alkali salts of alpha-alanine
In this work, physicochemical properties such as density, viscosity, refractive index, and electrical conductivity of aqueous alkali (potassium or sodium) salts of the amino acid alpha-alanine (ALA), were measured at temperatures from (303.15 to 343.15) K and concentrations ranging from (0.5 to 3.5) M. Density and viscosity measurements were performed using the vibrating tube and the falling ball techniques, respectively. The refractive index at the sodium D line was measured in an automatic refractometer, while the electrical conductivity was measured using a commercial conductivity meter. An empirical equation was applied to correlate the density, refractive index, and electrical conductivity of the amino acid salt solutions with temperature and amino acid salt concentration, which gave average absolute deviation values of 0.03%, 0.01%, and 0.6%, respectively. The variation of the viscosity as a function of temperature and amino acid salt concentration was accurately represented by a modified Vogel-Tamman-Fulcher equation at an average absolute deviation of 0.5%. (C) 2014 Elsevier Ltd. All rights reserved.