羟基铁插层膨润土的制备及其对铀(VI)的吸附特性与机制

通过羟基铁对钠基膨润土插层改性制备了羟基铁插层膨润土（OH-Fe-Bent），用于去除废水中的U（VI）。实验考察了pH值、U（VI）初始浓度、温度和吸附时间对OH-Fe-Bent吸附U（VI）效果的影响，并进行吸附动力学和热力学分析。采用FTIR、SEM、XRD等手段分析相关吸附机制。实验结果表明:OH-Fe-Bent吸附U（VI）的最佳pH为4，在温度为15℃，投加量为0.8 g/L，U（VI）初始浓度为10 mg/L时，OH-Fe-Bent对U（VI）的去除率达到99.55%，吸附平衡时间为90 min。Langmuir等温吸附模型和准二级动力学模型（相关系数的平方约为1）均可较好地拟合其吸附过程，理论饱和吸附量可达97.09 mg/g，OH-Fe-Bent对U（VI）是单分子层吸附。FTIR、SEM分析表明OH-Fe-Bent吸附U（VI）后自身结构没有改变，XRD分析表明羟基铁已经成功插入膨润土层间。 

Preparation of hydroxy-Fe intercalated bentonite and its adsorption characteristics and mechanism of uranium(VI)

Hydroxyl Fe intercalated bentonite (OH-Fe-Bent) was prepared by Na-bentonite while using hydroxyl Fe as intercalated material. The synthesized OH-Fe-Bent composites applied to adsorb U(VI) from water solution. The effects of pH value, initial U(VI) concentration, temperature and contact time on adsorption of U(VI) for OH-Fe-Bent were experimentally determined, and the process of adsorption was investigated by kinetic and thermodynamic analysis. The corresponding adsorption mechanisms were analyzed by FTIR, SEM, and XRD etc. The experimental results indicate that the maximum adsorption capacity occurs at pH 4 and the removal rate of U(VI) for OH-Fe-Bent reaches 99.55% for initial U(VI) concentration of 10 mg/L and adsorbent dosage of 0.8 g/L at 15℃. Meanwhile the adsorption reaches equilibrium within 90 min. The adsorption process fits well with the Langmuir isotherm adsorption model and pseudo second-order kinetic model (square of correlation coefficient is about 1), and the theoretical saturated adsorption capacity is 97.09 mg/g, adsorption mechanism of U(VI) for OH-Fe-Bent is a monolayer adsorption. The FTIR and SEM analyses show that the structure of OH-Fe-Bent has no change after absorbing U(VI) and the XRD analysis shows that the hydroxyl Fe has already intercalated bentonite.