Dispersion of barium titanate with polyaspartic acid in aqueous media

The colloidal stability of barium titanate (BT) aqueous suspensions with the sodium salt of polyaspartic acid (PApA-Na) at different pH values has been investigated by means of adsorption isotherm, zeta potential, sedimentation density and rheology characterization. The adsorption of PApA-Na onto BT surfaces is found to be pH dependent. Results show that PApA adsorption follows Langmuir monolayer adsorption isotherms and the amount of PApA-Na required to stabilize aqueous BT suspensions decreased as pH increased. The mechanism of stabilization of BT is shown to be a combination of electrostatic repulsion and steric hindrance under the experiment conditions used. As for the passivating power of PApA-Na, about 7-times reduction in Ba2+ ion leaching in 24 h is observed.