从模拟放射废液中去除Ce(Ⅳ)的吸附剂筛选和性能研究

Screen Experiments and Adsorption Performance Study of Adsorbents for Removing Ce(Ⅳ)from Simulated Radioactive Waste Liquid

研究了多种MOF材料对溶液中铈离子的吸附性能,经过对比得出,铜基MOF材料Cu-BTC对Ce(Ⅳ)的吸附效果最佳。采用SEM,BET,XRD,FT-IR等方法对其结构和形貌进行表征,并考察平衡时间、温度、初始浓度、pH、离子强度等参数对吸附行为的影响;对吸附前后的Cu-BTC进行XPS分析,考察其对Ce(Ⅳ)的吸附机制;另以实际放射性废水作为研究对象,探究Cu-BTC对真实放射性废液中α核素的吸附性能。结果表明:Cu-BTC对Ce(Ⅳ)离子的吸附在2 h内达到吸附平衡,吸附剂投加量一定时,平衡吸附量随溶液中铈离子初始浓度的增大而增大,平衡吸附率反之;溶液pH的增大与离子强度的减小可促进Cu-BTC对Ce(Ⅳ)的吸附;吸附等温线的研究表明Cu-BTC的吸附行为符合Langmuir等温吸附模型,以化学吸附为主,吸附过程为自发的吸热反应,低温有利反应的进行。此外,Cu-BTC对实际放射性废水中的α核素有较好的处理效果,平衡吸附比为52.51%。

The adsorption performance of a variety of MOF materials to cerium ions in the solution was studied.After comparison,it is concluded that the copper-based MOF material Cu-BTC has the best adsorption effect on Ce(IV).The structure and morphology were characterized by SEM,BET,XRD,FT-IR and other methods,and the effects of equilibrium time,temperature,initial concentration,pH,ionic strength and other parameters on the adsorption behavior were investigated.XPS analysis was carried out on Cu-BTC before and after adsorption to analyze its adsorption mechanism to Ce(Ⅳ).In addition,actual radioactive wastewater was used as the research object to explore the adsorption performance of Cu-BTC on low-and medium-level radioactive wastewater,aiming to provide a theoretical data basis for the radioactive wastewater treatment process.The results show that the adsorption of Ce(Ⅳ)ions by Cu-BTC can reach more than 99%within 2 h.When the adsorbent dosage is constant,the equilibrium adsorption capacity increases with the increase of the initial concentration of cerium ions in the solution.The adsorption rate is vice versa.The increase of solution pH and decrease of ionic strength can promote the adsorption of Ce(IV)on Cu-BTC.The study of adsorption isotherms shows that the adsorption behavior of Cu-BTC conforms to the Freundlich adsorption isotherm model,that is,it is mainly physical adsorption.The adsorption process is a spontaneous endothermic reaction,and low temperature is favorable for the reaction to proceed.