Aggregation in dispersions of hematite and of hematite-akageneite composite containing anionic surfactants

ABSTRACT

The aggregation in dispersions of iron oxides was studied by dynamic light scattering and by TEM. In spite of high absolute value of zeta potential induced by specific adsorption of alkyl (C12–C16) sulfates, the particles showed substantial degree of aggregation. The particle size distributions observed in SDS-stabilized dispersions by dynamic light scattering were sensitive to the impurities contained in reagent-grade SDS. Namely, different specimens of reagent-grade SDS produced very different particle size distributions at otherwise identical experimental conditions.

GRAPHICAL ABSTRACT

KEYWORDS:

• Aggregation
• ionic surfactant
• specific adsorption
• TEM

Acknowledgments

A grant from Alexander von Humboldt Foundation is gratefully acknowledged. Sabine Siegmund and Olaf Niemeyer are acknowledged for their assistance in the experiments.