Electrokinetic and rheological properties of Na-bentonite in some electrolyte solutions

Electrokinetic and rheological properties of Na-bentonite suspensions were investigated in the presence of various electrolyte solutions including LiCl, NaCl, KCl, NH4Cl, NaClO4, CH3COONa, NaNO3, Na2SO4, Na3PO4, CuCl2, MnCl2, CaCl2, BaCl2, NiCl2 and AlCl3. It was found that divalent cations (Cu2+, Mn2+, Ca2+, Ba2+ and Ni2+) and trivalent cation (Al3+) were potential determining cations for the Na-bentonite suspensions. Trivalent cation, Al3+, changed the surface charge of Na-bentonite from negative to positive. The zeta potential measurements showed that monovalent counter-cations and mono-, di- and tri-valent anions were indifferent ions for the Na-bentonite suspensions. The plastic viscosity and the Bingham yield stress values of the Na-bentonite suspensions were also determined in the presence of electrolyte solutions.