Measurements started with the potentiometric titration of the supporting electrolyte. Then, the Cr2O3 suspension in the absence and presence of LSZ was titrated. The LSZ concentration was 10, 50, 100, 300 or 500 ppm. The thermostated vessel was filled with 50 cm3 of the appropriate solution and then 1.5 g of the solid was added. The systems were titrated with 0.1 M NaOH. The measurements started at the J 113397 value approximately equal to 3.5.
2.2.2. Electrokinetic potential measurements
The experiments were performed using a zetameter Zetasizer 3000 (Malvern Instruments). The apparatus determines the electrokinetic potential of colloids moving in the electric field on the steady level of the electrophoretic cell. The potential reading is appendicular skeleton made automatically when the particle movement is compensated for by the applied voltage. According to Smoluchowski, the speed (u) of the colloidal particles moving in the electric field is associated to the zeta potential (ζ) by the equation:equation(2)?=αuDFηwhere α – the factor depending on the particle shape (for spherical particles α = 6π, for cylindrical α = 4π), D – the dielectric constant, F – the electric field strength, η – the viscosity.