Effect of sodium acetate on the volumetric behaviour of some mono-, di-, and tri-saccharides in aqueous solutions over temperature range (288.15 to 318.15) K

Abstract

The standard partial molar volumes, V 2 ∘ at infinite dilution of eight monosaccharides [ d(+)-xylose, d(−)-arabinose, d(−)-ribose, l(−)-sorbose, d(−)-fructose, d(+)-galactose, d(+)-glucose, and d(+)-mannose], six disaccharides [ d(+)-cellobiose, sucrose, d(+)-melibiose, d(+)-lactose monohydrate, d(+)-trehalose dihydrate, and d(+)-maltose monohydrate] and two trisaccharides [ d(+)-melizitose and d(+)-raffinose pentahydrate] (molalities of saccharides range from (0.03 to 0.12) mol · kg −1) have been determined in water and in (0.5, 1.0, 2.0, and 3.0) mol · kg −1 aqueous sodium acetate solutions at temperatures, T = (288.15, 298.15, 308.15, and 318.15) K from density measurements using a vibrating-tube digital densimeter. From these results, corresponding standard partial molar volumes of transfer, Δ t V 2 ∘ have been determined for the transfer of various saccharides from water to aqueous solutions of sodium acetate. Positive values of Δ t V 2 ∘ were obtained for most of the saccharides, whose magnitude increase with the concentration of sodium acetate as well as temperature. However, negative Δ t V 2 ∘ values were observed for l(−)-sorbose, d(−)-fructose and d(+)-xylose at lower concentrations of co-solute. The negative magnitude of Δ t V 2 ∘ values decrease with rise of temperature from (288.15 to 318.15) K. Pair and higher order volumetric interaction coefficients have been determined by using McMillan–Mayer theory. Partial molar expansion coefficients, ( ∂ V 2 ∘ / ∂ T ) p and the second derivatives ( ∂ 2 V 2 ∘ / ∂ T 2 ) p have also been estimated. These parameters have been utilized to understand various mixing effects in aqueous solutions due to the interactions between solute (saccharide) and co-solute (sodium acetate).