氟磷灰石对酸性水溶液中铀(VI)的去除研究

随着全球核能的开发利用, 铀已成为土壤、地表水和地下水的常见污染物, 从含铀废水中去除铀(VI)已成为迫切需要。本工作以氟化钙、焦磷酸钙、氢氧化钙为反应原料合成氟磷灰石, 系统研究了其对铀(VI)的去除性能并采用不同测试手段对吸附铀(VI)前后的氟磷灰石进行表征, 揭示了其相关去除机理。结果表明: 在温度为308 K, pH=3, 固液比为0.12 g/L, 平衡时间为120 min, 初始铀浓度为100 mg/L的条件下, 氟磷灰石对铀(VI)的吸附容量可达655.17 mg/g, 其吸附过程符合准二级动力学和Langmuir等温吸附模型, 且为自发和吸热过程。氟磷灰石对铀(VI)的去除机理为表面矿化, 吸附铀(VI)的氟磷灰石表面产生了新相准钙铀云母Ca(UO₂)₂(PO₄)₂·6H₂O], 准钙铀云母在pH≥3水溶液中能保持较高稳定性。因此, 氟磷灰石可以作为一种有前景的矿化剂, 用于含铀废水的净化和固体化处理。

Removal of Uranium (VI) from Acidic Aqueous Solution by Fluorapatite

Removal of uranium (VI) from uranium (VI) containing waste water is urgently needed with the global nuclear energy exploitation. The present work completed synthesis of fluorapatite and removal of uranium (VI). Fluorapatite was synthesized using calcium fluoride, calcium pyrophosphate and calcium hydroxide as the raw materials. The fluorapatite before and after adsorption of uranium (VI) was characterized. The experimental results show that, at condition of 308 K, pH=3, solid-liquid ratio of 0.12 g/L, equilibrium time of 120 min and initial uranyl ion concentration of 100 mg/L, the adsorption capacity of uranium (VI) by fluorapatite reaches 655.17 mg/g. Adsorption process of uranium (VI) by fluorapatite is in accordance with the pseudo-second-order kinetics and Langmuir isotherm adsorption model. Adsorption of uranium (VI) by fluorapatite is a spontaneous and endothermic reaction. The removal of uranium (VI) by fluorapatite is ascribed to surface mineralization. After uranium (VI) is absorbed, a new phase of meta-autunite Ca(UO₂)₂(PO₄)₂·6H₂O] is generated on the surface of fluorapatite. The meta-autunite can maintain high stability in the pH≥3 aqueous solution. Above results indicate that fluorapatite can be used as a promising mineralizer for purification and solidification of uranium (VI) containing waste water.