The structures of the products of hydrothermal crystallisation of zirconium tungstate and molybdate gel-generators previously refluxed in water solution of concentrated hydrochloric acid are closely related to the structures of initial amorphous precursors. The coordination polyhedra of Zr atoms in both crystalline and amorphous zirconium tungstate and molybdate are pentagonal bipyramids built up from oxygen atoms surrounding the central atom in a regular manner. The distances and dihedral and torsion angles are close to the values for ideal polyhedra. The central Zr atoms are located in gravity center of oxygen polyhedra. The activity of the extracted indium is measured by Liquid Scintillation Counting.
Nuclear industry produces and stores large volumes of radioactive waste solutions.
Since the radioactive elements in most waste solutions are in trace concentrations and the waste solutions contain large excesses of inactive metal ions, highly selective separation methods are needed for the removal of radionuclides. A number of inorganic ion exchange materials are very selective to key radionuclides and they can play an important role in solving these problems. Therefore, several inorganic ions exchangers are needed for the removal of most harmful radionuclides from a variety of solutions. This paper discusses the use and requirements of inorganic ion exchange materials in nuclear waste management. Special attention is paid to the novel ion exchange materials developed in the Laboratory of Radiochemistry, University of Helsinki.