Zirconium Molybdate Research Articles

The preparation and crystal structure of a basic zirconium molybdate and its relationship to ion exchange gels

ZrMo 2O 7(OH) 2(H 2O) 2 was prepared in microcrystalline form by refluxing precipitated zirconium molybdate gels in 1–4M HCl. Macroscopic single crystals have been grown under hydrothermal conditions. In their amorphous, precipitated-gel form the gels are known to function as cation-exchangers. The crystal structure of zirconium molybdate was determined from integrated precession photographs using MoKα radiation. Crystal data: tetragonal space group 14 1 cd (No. 110); a = 11·45±0·01 A ̊ c = 12·49±0·01 Å (25°C); ϱ obs = 4·0±0·1, ϱ calc = 3·774 g. cm −3. The structure, refined by block diagonal least squares to (conventional) R = 0·037, is a three-dimensional network of cross-linked chains built-up of quite regular [ZrO 3 eq (OH 2 eq O 2 ax ]-pentagonal bipyramids and distorted cis-MoO 4(OH)(H 2O-octahedra. The structure is held together primarily by [Zr-O (and OH)-Mo]-bridges; chains of hydrogen bonds involving the oxo-, hydroxo-, and aquo- groups play a secondary role. Intermatomic distances and angles are normal, however, one oxygen atom has unusual coordination geometry; it forms a three-way bridge in a (symmetry-required) planar [ZrOMo 2]-moiety. The structure provides a rationale for the thus far observed physical and chemical properties.

Adsorption of the Elements on Inorganic Ion Exchangers from Nitrate Media.

The distribution coefficients of 60 metal ions were measured for four inorganic ion exchangers from nitrate media over the pH range of 1 to 5. The exchangers are hydrous zirconium oxide, zirconium phosphate, zirconium tungstate, and zirconium molybdate. The data are presented as plots of log distribution coefficient vs pH in a series of four periodic charts. Separations of analytical interest are presented. (auth) hydroxide (in both hydrated and anhydrous forms) and hyperol dissolved in absolute ethyl alcohol as a source of hydrogen peroxide. (P.C.H.)