Precipitation from solutions niobium peroxide

A method of separation which avoids the preparation of the double fluorides consists in fusing the mixed niobic and t an tali c acids with sodium carbonate and nitrate, the product is digested with warm water and a current of carbon dioxide is passed through the solution. It is claimed that only tantalic acid is precipitated.5 This process has, however, been the subject of adverse criticism.6 Partial separation of niobium from tantalum can be effected by warming the mixed, freshly precipitated, hydrated oxides with a mixture of hydrogen peroxide and hydrochloric acid the niobium dissolves readily, while the tantalum dissolves only sparingly.7... 

Addition of LiOFI H2O (or Na2C03) solntion to the niobium peroxo solution prodnces a clear colorless solntion with lots of effervescence. The solution remains clear when it is allowed to stand at room temperature for several hours. However, when the solntion is warmed on a water bath at 80 to 90°C for 10 min, the reaction becomes exothermic with further evolution of gas. After a few seconds, some white compound precipitates out. The FT IR for this compound is shown in Fignre 6.6b. The infrared (IR) features obtained for the white powder were completely different from those of the peroxide precursor, with a broad band being observed between 7(X) cm and 400 cm in the case of lithium salt (Figure 6.6b) and a wide band at 540 cm with a shoulder at 770 cm in the case of sodium, with additional bands at about 3400 cm and 1600 cm due to coordinated water. The FTIR spectra for the lithium and sodium powders heated at 400°C showed IR features that are characteristic of LiNbOj and NaNbOj. Thus... 

The Pu(rV) oxalate process achieves decontamination factors of about 3 to 6 for zirconium-niobium, 12 for ruthenium, 60 for uranium, and 100 for aluminum-chromium-nickel. As compared with peroxide precipitation, the oxalate process achieves less decontamination from impurities, but the solutions and solids are more stable and safer to handle. It is more suitable for processing solutions containing high concentrations of impurities that would catalyze peroxide decomposition. 

---