改性类水滑石的制备及其去除溶液中Eu(Ⅲ)和U(Ⅵ)

Preparation of Modified Hydrotalcite and Adsorption of Eu(Ⅲ)and U(Ⅵ)in Aqueous Solution

通过水热合成法成功地制备了丙三醇改性Ni/Al型水滑石(GMH),并通过批量处理法和静态吸附法考察了在固体投加量、溶液pH、离子强度、腐殖酸、接触时间和温度等因素影响下,溶液中Eu(Ⅲ)和U(Ⅵ)在GMH上的吸附行为。采用扫描电镜(SEM)、红外光谱(FTIR)、X射线衍射(XRD)等表征手段对材料吸附前后进行分析,结合吸附动力学和热力学模型对吸附机理进行探讨。结果表明,溶液pH值对Eu(Ⅲ)和U(Ⅵ)在GMH上的吸附行为影响显著,在pH=7.0左右时吸附率达到最大;准二级动力学模型和Langmuir等温线模型可以很好地描述Eu(Ⅲ)和U(Ⅵ)在GMH上的吸附过程,且此过程是自发的、吸热的过程;实验条件下,GMH对溶液中的Eu(Ⅲ)和U(Ⅵ)的最大理论吸附量分别为511mg/g和441mg/g;GMH对溶液中Eu(Ⅲ)的吸附主要是通过静电相互作用、内层表面络合以及离子交换相互作用实现;而对U(Ⅵ)的吸附主要是通过静电相互作用和内层表面络合作用实现的。实验表明,合成材料在含低放废水的有效净化和修复方面具有很大的应用前景。

In this work,glycerol-modified Ni/Al hydrotalcite(GMH)was successfully prepared by hydrothermal synthesis method,and the batch technique and static adsorption method were used to study the adsorption behavior as a function of solid-to-liquid ratio,pH value,ionic strength,humic acid,contact time and temperature.The characterizations of SEM,FTIR and XRD were used to analyze the materials before and after adsorption,and the adsorption mechanism was discussed by adsorption kinetics and thermodynamic model.The results show that the pH value of the solution has a significant effect on the adsorption behavior of Eu(Ⅲ)and U(Ⅵ)on GMH,and the adsorption percentages reaches the maximum at pH=7.0.The pseudo-second-order kinetic model and the Langmuir isotherm model can well describe the adsorption process of Eu(Ⅲ)and U(Ⅵ)on GMH,and the adsorption process is spontaneous and endothermic.Under the experimental conditions,the maximum theoretical adsorption capacities for Eu(Ⅲ)and U(Ⅵ)onto GMH are 511 mg/g and 441mg/g in solution,respectively.The adsorption of Eu(Ⅲ)by GMH in solution is mainly dominated by electrostatic interaction,inner-sphere surface complexation and ion exchange,while the adsorption of U(Ⅵ)is mainly achieved by electrostatic interaction and inner-sphere surface complexation.Experiment results show that the synthetic material has a great application prospect in the effective purification and repair of low-level radioactive wastewater.