Aggregation and Colloidal Stability of Commercially Available Al₂O₃ Nanoparticles in Aqueous Environments.

ABSTRACT: The aggregation and colloidal stability of three, commercially-available, gamma-aluminum oxide nanoparticles (γ-Al₂O₃ NPs) (nominally 5, 10, and 20-30 nm) were systematically examined as a function of pH, ionic strength, humic acid (HA) or clay minerals (e.g., montmorillonite) concentration using dynamic light scattering and transmission electron microscopy techniques. NPs possess pH-dependent surface charges, with a point of zero charge (PZC) of pH 7.5 to 8. When pH < PZC, γ-Al₂O₃ NPs are colloidally stable up to 100 mM NaCl and 30 mM CaCl₂. However, significant aggregation of NPs is pronounced in both electrolytes at high ionic strength. In mixed systems, both HA and montmorillonite enhance NP colloidal stability through electrostatic interactions and steric hindrance when pH ≤ PZC, wher

SUBMITTER: Mui J 

PROVIDER: S-EPMC5302499 | biostudies-literature | 2016 May

REPOSITORIES: biostudies-literature