Synthesis and Characterization of Stable Aqueous Ceria Sols

Stable colloidal aqueous dispersions (sols) of cerium (IV) oxide of uniform size distribution were obtained by forced hydrolysis of cerium (IV) ions in the presence of diluted sulfuric or nitric acids. Synthesis of ceria sols was carried out using two commercially available precursors: Ce(SO4)(2) center dot 4H(2)O salt and 0.25 mol/L Ce(NO3)(4) aqueous solution. The precursors were dissolved in different concentrations of diluted sulfuric or nitric acid. After aging for various periods of time (2-24 h), the sols were cooled at room temperature. Sulfate and nitrate ions were removed from the sols particles by ultrafiltration. Characterization of the synthesized ceria sols has been made by X-ray diffraction, nitrogen adsorption/desorption, and DSC-TGA thermal analysis, as well as IR spectroscopy. Particle sizes, measured using a Zetasizer Nano equipped with a MPT-2 Autotitrator, range from 20 to 600 nm.