The limiting partial molar volume and apparent molar volume of glycylglycine in aqueous KCl solution at 298.15 and 308.15 K

Apparent molar volumes V-Phi of glycylglycine in aqueous KCl solutions have been obtained from densities at 298.15 and 308.15 K measured with a vibrating-tube densimeter. These data have been used to deduce partial molar volumes of transfer Delta trs V-Phi(0) from water to different KCl-water mixtures. Delta trs V-Phi(0) values are positive. This result arises from the interaction of KCl with the charged centers of glycylglycine. The results show that Delta trs V-Phi(0) depends less on temperature. Hydration numbers are calculated from V-Phi(0) data and Delta trs V-Phi(0) are interpreted in terms of various interactions. (c) 2004 Elsevier B.V. All rights reserved.