Abstract
The correlation between electrokinetic behavior and rheological phenomena of a highly concentrated coal water mixture (CWM) in the presence of a polyelectrolyte (sodium polystyrene sulfonate; PSS-Na) was studied by usual electrophoretic method and colloid vibration potential (CVP) technique. ζ-Potential determined by usual electrophoretic method was found not to be closely correlated to the viscosity of the CWM slurry. The structure of the electrical double layer around coal particles changes by dilution due to variation in the concentration of free polymer and eluted ions from the coal is the reason for this.
ζ-potential determined by the colloid vibration potential technique was shown to have goodcorrelation with the viscosity of the slurry over a wide range of volume fraction of coal particles, when the conductivity of dispersed medium was maintained constant after dilution. At a constant volume fraction (φ=0.24), a certain value of PSS-Na additive maximized the ζ-potential of each sample. This was because the additive functioned as a counter ion for the surface charge of particles following saturated adsorption and thereby reducing the ζ-potential of the particles.
