Silver colloids and interfacial colloids - Adsorption of alizarin yellow 2G and its effect on colloidal nucleation

Alizarin yellow 2G, 5-((3-nitrophenyl)azo)-2-hydroxybenzoic acid sodium salt (AY), strongly interacts with silver ions and adsorbs on silver metal surfaces. It competes with other anions (anisate anion) over adsorption sites and alters the energetics of formation of the small silver metal cluster intermediates involved in the process of colloid production. The increase in the colloid nucleation rate, compared to the growth, results in a larger number of slightly smaller silver particles than that obtained in the absence AY. The larger number of colloidal particles, that function as interfacial colloidal stabilizers of a water/oil macroemulsion, brings about a decrease in the size of the emulsion droplets. The adsorption of AY on the silver colloid is studied by surface Raman spectroscopy. It is found to adsorb in a flat conformation, forming a surface molecular species resembling the complex of AY and silver ions.