Adsorption of cationic polyacrylamide on the surface of mesoporous nanozirconia and its influence on the solid aqueous suspension stability.

The adsorption mechanism of cationic polyacrylamide (PAM) on the mesoporous nanozirconia was studied. The effects of solution pH (in the range 3–10) and cationic groups content (20–80%) in the polymeric chains were examined. The influence of polymer adsorption on both the structure of electrical double layer and stability of aqueous ZrO 2 suspension was determined. It was shown that the porosity of zirconia (mean pore diameter 31 nm) has the greatest impact on the PAM adsorption level at pH 9, at which molecules can penetrate into the pores. As a result, the greatest amount of adsorbed polyacrylamide was obtained. The specific conformation of adsorbed macromolecules (containing positively charged cationic groups) is responsible for the observed decrease of the solid surface charge density and increase of the zeta potential of nanozirconia particles. Polyacrylamide has the greatest impact on the ZrO 2 suspension stability at pH 6 (significant improvement of the system stability due to electrosteric interactions). [ABSTRACT FROM AUTHOR]