EXAFS Study of Zirconium Monobutylphosphate and Zirconium Dibutylphosphate

EXAFS (Extended X-ray Absorption Fine Structure) measurement was carried out for the study of the local structure around Zr in precipitates of Zr (IV) -monobutylphosphate and Zr (IV)-dibutylphosphate, which are one of the main species of so-called “The Third Phase”. Both gelatinous and dried samples show the same Fourier transform spectra for Zr(IV)-monobutylphosphate and Zr (IV)-dibutylphosphate. The precipitates in Zr (IV)-monobutylphosphate have the bridging phosphate between Zr ions, Zr-phosphate-Zr, as well as the bridging hydroxyl between Zr ions, Zr-OH-Zr, while no bridging phosphate in Zr(IV)-dibutylphosphate. This fact indicates the layer structure with 16Å distance for Zr(IV)-monobutylphosphate described in Part (I)of the present reports. As for the re-dissolution of Zr(IV)-dibutylphosphate precipitates with increasing tributylphosphate observed in Part (I), the absence of the bridging phosphate in Zr(IV)-dibutylphosphate plays an important role. The chemical structures postulated by elemental analysis, infrared spectra, 1H-NMR and X-ray diffraction in Part (I) were confirmed in detail from the present results of EXAFS. It was confirmed ZrO2+, zirconyl ion, does not exist in aqueous solutions.