Dispersion of H-magadiite and H-kenyaite particles by ion exchange of H+ with alkali ions

Synthetic magadiite and kenyaite and their silicic acids were obtained as spherical and loosely packed aggregates composed of platelike crystals. Particle dispersion of the silicic acids was investigated by scanning electron microscope (SEM) observation, electrokinetic characterization, and particle size distribution analysis. SEM. observation indicated that the particles of these compounds were dispersed into individual platelets by treatment with KOH, LiOH, and NH4OH solutions, but this phenomenon did not occur in NaOH solution. The effectiveness of alkaline solutions for dispersion followed the order LiOH > KOH > NH4OH. H-kenyaite particles were also found to be more easily delaminated than H-magadiite particles. Measurement of relative acoustophoretic mobility of the particles and solution specific conductivity indicates that the dispersion is due to the increase in electrical double-layer repulsion between particles surrounded by OH- anions in solution.