Effect of Formation Temperature of Zirconium Dioxide on its Phase Composition and the Efficiency of Adsorptive Removal of Phosphate Anions from a Water Solution

Zirconium dioxide samples with different crystallinity and phase compositions have been obtained by calcination of a mixture of zirconium oxychloride and sodium bicarbonate at temperatures ranging from 150 to 800°C. It is established that amorphous ZrO₂ with an zirconium oxycarbonate admixture is formed at 150-200°C. A sample obtained at 400°C contains 50% of the tetragonal phase and 50% of the amorphous ZrO₂ phase, while a mixture of tetragonal and monoclinic phases is formed at 600°C and 800°C (83% of t-ZrO₂/17% m-ZrO₂ and 27% of t-ZrO₂/73% m-ZrO₂, respectively). It is shown that zirconium dioxide obtained at 150°C has the highest efficiency of adsorptive removal of phosphate anions from an water solution as compared with other studied samples.