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基于曼尼希反应原理,采用化学接枝法合成了氨基膦酸衍生硅胶吸附剂,考察了其对溶液中铂、钯和铀的吸附分离性能。测试了溶液pH、吸附时间、初始金属离子浓度、离子强度和固液比对吸附的影响,吸附选择性及吸附剂的重复使用性能,分析了吸附机理,并用动态柱法对模拟高放废液中三种金属离子进行了回收。衍生硅胶对铂、钯和铀的吸附与溶液pH值关系密切,离子强度、固液比对吸附的影响不大;吸附过程符合准二级吸附动力学模型和Langmuir等温吸附模型。在pH2时,吸附剂3h内对铂、钯的平衡吸附容量分别为18.5mg·g-1和19.9mg·g-1,pH6时3h内的铀平衡吸附容量为62.1mg·g-1,利用不同pH条件下的吸附差异可分离回收溶液中的铂、钯和铀。受金属离子溶液化学形态控制,吸附剂对铂、钯有较好的吸附选择性。用5mL5%硫脲可完全解吸吸附于衍生硅胶上的铂和钯,5mL0.1mol·L-1HNO3可定量解吸铀。衍生硅胶吸附材料可回收重复使用,采用双柱联合可定量回收模拟废液中的三种金属元素。
Based on the Mannich reaction principle, aminophosphonic acid derivatized silica gel adsorbent was synthesized by chemical grafting method. The adsorption and separation performance of platinum, palladium and uranium in solution was investigated. The effects of solution pH, adsorption time, initial metal ion concentration, ionic strength and solid-liquid ratio on adsorption, adsorption selectivity and adsorbent reusability were tested. The adsorption mechanism was analyzed. Three kinds of metal ions were recovered. The adsorption of platinum, palladium and uranium on the derivatized silica gel is closely related to the pH value of the solution. The ionic strength and the solid-liquid ratio have little effect on the adsorption. The adsorption process accords with the quasi-second-order adsorption kinetics model and the Langmuir isothermal adsorption model. At pH2, the equilibrium adsorption capacities of platinum and palladium for 3h were 18.5mg · g-1 and 19.9mg · g-1, respectively, and the equilibrium adsorption capacity of uranium was 62.1mg · g-1 within 3h at pH6 The adsorption difference under different pH conditions can be separated and recovered platinum, palladium and uranium in solution. Controlled by the chemical form of the metal ion solution, the adsorbent has good adsorption selectivity to platinum and palladium. With 5mL5% thiourea can be completely desorbed on the derivatized silica gel platinum and palladium, 5mL0.1mol · L-1HNO3 quantitative desorption of uranium. The derivatized silica gel adsorbent can be recycled and reused. The double column combination can quantitatively recover the three metal elements in the simulated waste liquid.