焙烧态镁铝水滑石对I^-的吸附行为研究

Adsorption of I^- on Calcined Mg-Al Hydrotalcite

采用共沉淀法制备了镁铝水滑石,并利用XRD、FT-IR和SEM对材料进行了表征。在此基础上,系统研究了不同焙烧温度、初始pH值、振荡时间、初始I^-浓度等对焙烧态镁铝水滑石吸附I^-性能的影响。结果表明:500℃焙烧条件下所制备的镁铝水滑石CLDH-500对I^-的吸附性能最优。在初始I^-浓度为500mg/L、初始pH=6.0的条件下,8h达到吸附平衡,最大吸附容量为217.22mg/g。对吸附过程用准一级、准二级动力学模型和粒内扩散模型模拟。结果显示,其吸附过程符合准一级动力学模型和粒内扩散模型(R^2>0.96);Langmuir模型拟合结果(R^2>0.99)显示,I^-在CLDH-500上为单分子层吸附。该研究结果可为放射性废液中I^-的去除提供技术和理论支持。

The layered double hydroxides （LDH） containing Mg2＋ and Al3＋ in the brucite-like layers and interlayer carbonate ions were prepared by co-precipkation meth- od and characterized by XRD, FT-IR and SEM. The adsorption behavior of I- on LDH was investigated as a function of calcination temperature, initial pH, contact time and initial I concentration. The results show that the calcined LDH under 500℃ （CLDH- 500） has the highest adsorption capacity for I-. The maximum adsorption capacity of 217.22 mg/g is achieved at pH-6 with 8 h contact time when initial I- concentration is 500 mg/L. Pseudo-first-order and pseudo-second-order kinetic models and intrapartiele diffusion model were used to describe the adsorption process, and the results indicate that the adsorption data correlate well with pseudo-first-order kinetic model and intra- particle diffusion model （RE〉0.96）. The fitting results of Langmuir isotherm model （R2〉0.99） show that the adsorption of I- on CLDH-500 is monolayer. This method can provide technical and theoretical support for the removal of I- from radioactive waste water.