CONTROL OF DISPERSION OF AGGLOMERATED PAR TICLES IN WATER BY ELECTROSTATIC REPULSION FORCE

The effect of electrostatic repulsion force arising from the surface p otential phi and the double layer 1/kappa around a particle on dispers ion or de-agglomeration of agglomerated particles in water is discusse d. Several suspensions of PSL (polystyrene latex) particles in an aggl omerated state where and 1/kappa are respectively controlled by the pH and the electrolyte concentration C-e were prepared. They were accele rated in a convergent nozzle to give an external force on particles an d agglomerated particles were dispersed into primary particles. PSL pa rticles thus dispersed were observed with an optical microscope. It wa s found that the dispersion of agglomerated particles was enhanced wit h an increase of phi and C-e under a constant external force qr a cons tant flow rate in the nozzle. It is well understood that the dispersio n of particles with higher surface potential phi is much easier. It is , however, intuitively curious that the dispersion of agglomerated par ticles in higher electrolyte concentration C-e is much easier, since c oagulation is usually enhanced in such a higher C-e suspension. The ex perimental results may be applied to control the dispersion of agglome rated particles in water.