EFFECT OF INTERCALATION OF METAL-IONS ON THE COLLOIDAL AND SOLID PROPERTIES OF VANADIUM PENTAOXIDE HYDRATE, V2O5NH2O

The colloidal stability of V2O5nH2O was studied on the basis of the measurements of critical flocculation concentration (CFC) by metal ions, amount of ions exchanged (or intercalated), and zeta-potential. In total, the CFC values obeyed the Schulze Hardy law and strong Hofmeister's series was found in the systems including alkaline ions. The sequence of colloidal stability of V2O5nH2O in the electrolyte solutions was related to the intercalation of metal ions in the interlayer spaces of the solid. The largest CFC value for Li+ (87 mmol dm-3) was explained by smaller affinity of Li+ to be intercalated in V2O5nH2O as well as smaller Hamaker constant of the intercalated solid compared to the other systems. Effect of intercalation of metal ions on the crystalline properties of the materials was measured by use of XRD and electron microscope. Under highly dehydrated condition the ions whose radii are smaller than 0.1 nm are captured in the structure of V2O5nH2O without changing interlayer distances, while those larger than 0.1 nm increase the interlayer distance. In a saturated H2O vapor interlayer distances increased with increasing charge of intercalated ions. However, when intercalated with ions carrying the same valency the interlayer distances of the sample decreased with decrease in the hydration property of ions. Hydrolyzable Cr3+ gave exceptionally larger interlayer distances, both in a vacuum and in H2O vapor.