Aggregation stability of gold citrate hydrosol: Effect of ozone

Optical spectroscopy, dynamic light scattering, electrophoresis, and transmission electron microscopy are used to study the action of ozone on the stability of a gold hydrosol produced by the citrate method. It is shown that gold nanoparticles are not oxidized, even upon long-term ozonation. At short times of ozonation, changes that occur in the state of the sol are reversible. Nevertheless, even at this stage, organic ligands, which stabilize the hydrosol, are oxidized, while adsorbed ozone molecules can play the role of a stabilizer. At long ozonation times, when the oxidation of organic substances present in the system is actually completed, the colloidal solution loses its aggregation stability.