NMR study on the state of zirconium- and hafnium ions in aqueous solutions

The state of zirconium and hafnium ions is studied by the NMR method within the range of zirconium and hafnium oxychloride concentrations of 0.3-2.5 mol/l in an acid medium (pH approximately 0.5). It is shown that under these conditions the zirconium and hafnium ions contain two OH-groups per one metal ion, which is in agreement with the literature formula for the Zr4(OH)8J8+ tetramer. The tetramer is verified by the NMR method to be a basic structural unit while the state of Zr ions does not vary within the 0.01-15 mol/l region and that of Hf ions does not vary within the whole concentration range being studied (0.01-2.5 mol/l) At zirconium and hafnium concentrations exceeding 1.5 or 2.5 mol/l, respectively, the degree of polymerization increases