Electrostatic Effect on the Hydration Layer of Colloidal Silica Particles

✍ Scribed by Shigeo Sasaki; Hiroshi Maeda

• Publisher: Elsevier Science
• Year: 1994
• Tongue: English
• Weight: 192 KB
• Volume: 167
• Category: Article
• ISSN: 0021-9797
• DOI: 10.1006/jcis.1994.1342

✦ Synopsis

The hydrodynamic radii of colloidal silica particles in the aqueous solutions were measured under various conditions of (\mathrm{pH}) and salt concentration by means of the dynamic light scattering technique. In the salt free solutions the observed hydrodynamic radius increased by (1 \mathrm{~nm}) from (13 \mathrm{~nm}) at (\mathrm{pH}) below 8 to (14 \mathrm{~nm}) at (\mathrm{pH}) above 9 according to the ionization of silanol groups. At pH above 9 , the radius decreased from (14 \mathrm{~nm}) in salt free solutions to (13 \mathrm{~nm}) at the salt concentration of (10^{-2} M). These results suggest that the strong electrostatic electric field makes the hydration layer on the surface of a silica particle thicker. 1994 Academic Press, Inc.