Density, Viscosity, and Refractive Index of Aqueous Solutions of Sodium Lactobionate

Abstract

The density, viscosity, and refractive index of aqueous solutions of sodium lactobionate were measured as a function of molality m = 0.0251, 0.0502, 0.0753, 0.100, 0.126, 0.151, 0.176, and 0.201 mol·kg –1 and temperature T = 288.15, 293.15, 298.15, 303.15, 308.15, 313.15, 318.15, and 323.15 K. They all increase with decreasing temperature and with increasing concentration of sodium lactobionate. The Vogel–Tamman–Fulcher equation was used to correlate the dependence of density and viscosity on molality and temperature, and the refractive index was fitted by a polynomial model. The parameters were acquired by least-squares regression method for these models, and the calculated values showed good agreement with the experimental data for density, viscosity, and refractive index. The volumetric properties, including apparent molar volume, excess molar volume, and partial molar volume, among others, were determined according to the experimental values for sodium lactobionate mixtures. Furthermore, the relative viscosity and viscosity B coefficients were calculated. The molecule interactions and solution properties were studied on the basis of the evaluated thermodynamic property data. In the studied system, sodium lactobionate behaves as structure maker.