Tantalum sorption from chloride-fluoride solutions by anionites

The calculated and experimental data on sorption of tantalum ions from chloride-fluoride solutions by anionites of various classes and structures are considered and discussed. Based on the calculations carried out, it is shown that, in chloride-fluoride solutions, tantalum forms a whole series of complex ions, namely, chloride, fluoride, hydroxy, and mixed chloride-fluoride and hydroxychloride complex ions. The equilibrium of tantalum ions during their sorption from chloride solutions is investigated. The behavior of the tantalum ions during the sorption from hydrochloric acid solutions over a wide range of its concentration is interpreted from the viewpoint of the ionic state of the metal in the solution as well as the structure and functional features of ion exchangers. The conclusions made on the sorption chemistry are confirmed by the data of the IR spectroscopy investigations.