Interpreting titration data of aqueous latices by coupling ionization and ion-exchange equilibria

✍ Scribed by Marc Hlavacek; Pascal Chenevière; Michel Sardin; John Dodds

• Book ID: 103967070
• Publisher: Elsevier Science
• Year: 1995
• Tongue: English
• Weight: 724 KB
• Volume: 95
• Category: Article
• ISSN: 0927-7757
• DOI: 10.1016/0927-7757(94)03027-w

✦ Synopsis

Suspensions of colloidal latex particles with weak acid (carboxylic) and/or weak basic (amine) groups on their surface have been titrated with HC1. Analysis of the ionic composition of the liquid phase shows variations in the Na ÷ and C1-concentrations associated with variations in the pH of the suspensions. A model reaction scheme is proposed involving ionization of the surface groups and ion-exchange between the solid surface and the surrounding liquid. The numerical solution of this system gives a reasonably good agreement ( _ 5%) with the experimental results. The predictions of the model for the effects of the solids concentration and ionic strength are in agreement with known results concerning the "suspension effect". The surface charge values obtained from the model suggest that care should be taken when extrapolating measurements of the electrophoretic mobility of particles made at low solids concentration to higher solids concentrations.