Fundamental Study of "The Third Phase" formed in Extraction Processes of Nucler Fuel Reprocessing

本文用元素分析方法系统地研究了Zr与TBP的乏辐射产物HDBP、H_2MBP、H_3PO_1体系中沉淀物或“第三相”的形成条件、组成和结构。X射线衍射、红外光谱和1H-NMR。结果表明，锆离子与TBP贫化产物的络合作用是第三相形成的重要原因之一。（1）在低酸条件下，贫化产物共存时，对沉淀的形成有协同作用。(2)锆酸盐的形成取决于HDBP/Zr的摩尔比。沉淀物的量在摩尔比约为2时达到最大值，并随着HDBP浓度的增加而减少，最后在约10时消失。(3)以摩尔比约为2形成的钛酸盐具有化学式Zr（NO_3）_2（HDBP）_2（OH）_2。(4)Zr-H_2 MBP体系的稳定性 ...更多信息 用EXAES（Extended X-ray Absorption Fine Structure）方法研究了Zr（IV）-磷酸一丁酯和Zr（IV）-磷酸二丁酯沉淀物中Zr周围的局域结构，这两种沉淀物是所谓的“第三相”的主要物种之一。凝胶状样品和干燥样品均显示磷酸单丁酯和磷酸二丁酯的相同傅立叶变换光谱。磷酸单丁酯锆中的沉淀物在锆离子之间有磷酸根桥，即磷酸锆-锆。Zr（IV）-磷酸二丁酯中没有磷酸根桥连，而Zr（IV）-磷酸二丁酯中没有磷酸根桥连。这一事实表明，本报告第（I）部分中描述的磷酸单丁酯锆（IV）的层结构具有16埃的层间距。至于Zr（IV）-磷酸二丁酯的再溶解，在部分（I）中观察到随着磷酸三丁酯的增加而沉淀。在磷酸二丁酯锆（IV）中不存在桥连磷酸盐起重要作用。化学结构由元素分析确定。红外光谱根据EXAFS的结果详细地证实了（I）部分中的~ 1H-NMR和X-射线衍射。证实了ZrO 2<2->（锆氧离子）不存在于水溶液中。少

Formation conditions, compositions and structures of precipitates or "the third phase" were systematically examined in the systems of Zr and radiation depleted products of TBP, such as HDBP, H_2MBP, H_3PO_1, by means of elemental analysis. X-ray diffraction, infrared spectra and ^1H-NMR. It was confirmed that one of the most important origins for the third phase is a complexation between Zr ion and the depleted products of TBP. Followings were also elucidated:(1) When the depleted products co-exist with each other, the cooperative effects on the pre- cipitate formation appear in low acid solutions. (2) Precipitate formation depends on the mole ratio of HDBP/Zr. The amount of precipitate reaches the maximum at the mole ratio of approximately 2 and decreases with increasing concentration of HDBP and finally disappeals at approximately 10. (3) Precipitate formed at the mole ratio of approximately 2 has the chemical formula, Zr(NO_3)_2(HDBP)_2(OH)_2. (4) Precipitates of the Zr-H_2MBP syste … More m begin to appear at the concentration of H_2MBP in one order of magnitude smaller than of HDBP in Zr HDBP system.EXAES (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)-monobutyl- phosphate 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 16A^^ﾟ 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 pospuiated 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 ZrO^<2->, zirconyl ion, does not exist in aqueous solutions. Less