THE APPARENT AND PARTIAL MOLAR VOLUMES OF SODIUM CARBOXYMETHYLCELLULOSE IN ACETONITRILE-WATER MIXED SOLVENT MEDIA

摘要

The volumetric properties of Sodium Carboxymethylcellulose (NaCMC) in acetonitrile-water mixed solvent media containing (0.10, 0.20, and 0.40) volume fractions of acetonitrile were studied by measuring the density of solutions at temperatures (298.15, 308.15, 313.15, and 318.15) K. Besides studying the solvation behavior of the counterions, the study was focused on investigating the interactions between the counterion and the polyion. In the specified temperature range, a linear increase for apparent molar volume (φ v ) with increasing polyelectrolyte concentration was observed in a medium with fixed volume fractions of acetonitrile. However, at a given temperature as the medium became richer in acetonitrile the limiting partial molar volumes ( 0 2 ? V ) registered a decrease. But, when a polyelectrolyte solution in a fixed medium underwent a step-wise increase in temperature then 0 2 ? V values increased thereby leading to the inference that a temperature-induced desolvation of the counterions results in more counterion binding at higher temperatures.