Chemical Characterization of Transition Metal (V, Zr, Nb) Impurities in Rutile

The dissolution and chemical properties of vanadium, zirconium, and niobium in rutile lattice are analyzed by comparing the octahedral site preference energies, with respect to Ti4+ ion in solvent phase. The oxides are often present in rutile lattice and interfere in achieving the quality of pigment grade TiO2 due to favourable Gibbs energy for dissolution in the solvent rutile matrix. Binary mixtures of V2O5 – TiO2; Nb2O5 – TiO2 and ZrO2 – TiO2 with compositions of 80, 85, 90, 95 and 97 wt% TiO2 were made, pelletized and sintered at 1100 oC for 24 hours. The solid-solution mixtures were then cooled and leached in 2M NaOH for 3 hours at 60 oC. Phase and lattice parameter characterizations, and microstructural and compositional analyses were then carried out using X-ray diffraction and SEM/EDX, respectively. The leachates were analysed by Atomic Absorption Spectroscopy, using which the solute dissolution model for oxides were investigated.