Abstract

The purpose of this work is to investigate the effect of the addition of salts in the form of calcium chloride, sodium chloride and potassium chloride on the rheological and electrokinetic properties of diluted sodium carboxymethylcellulose (Na-CMC) dispersions (0.50%). The rheological data of a water-CMC-salt system were obtained using coaxial cylinder viscometer covering a wide range of shear rate (0 to 600 s^-1).  Ostwald–de Waelepower law was used for fitting flow curves of various samples. The presence of salts in CMC aqueous solutions leads to the reduction of the consistency index and the increase of flow index as salinity increases. When the concentration of salts is greater than 3%, the rheological parameters of CMC solutions in saline medium are quasi stable. The electrokinetic measurements show an increase of the zeta potential of CMC dispersions when the concentration of salts in solution increases. Calcium chloride caused the greatest increase in zeta potential. Excluding the monovalent cations, the divalent cation is able to reverse the sign of the zeta potential from negative to positive.

Key words: Rheology, zeta potential, salt, carboxymethylcellulose sodium (CMC).