Effect of sodium sulphate on the volumetric, rheological and refractometric properties of some disaccharides in aqueous solutions at different temperatures

Density, rho, viscosity, eta, and refractive index, n, of some disaccharides [D(+)-cellobiose, D(+)-lactose monohydrate, D(+)-maltose nionohydrate and sucrose] in water and in 0.49850 and 0.99705 mol kg(-1) aqueous solutions of sodium sulphate [Na2SO4] have been measured at four temperatures [288.15, 298.15, 308.15 and 318.15 K]. From these data, the apparent molar volumes, V,,, and viscosity-B-coefficients using Jones-Dole equation have been determined at different temperatures. The partial molar volumes of transfer, Delta V-t(2)0 at infinite dilution and B-coefficients of transfer, A,B, have been estimated for transfer of disaccharides from water to aqueous sodium sulphate solutions. Partial molar expansion coefficients, (partial derivative V-2(0)/partial derivative T)(P) and dB/dT coefficients have also been calculated. Gibbs free energy of activation of viscous flow has been calculated by using Feakin's transition-state theory for the studied systems. D(+)-Cellobiose has shown characteristically different hydration behaviour among the studied disaccharides. The signs and magnitude of Delta V-t(2)0 and Delta B-t parameters have been discussed in terms of various interactions occurring in these solutions.