羟基铋离子改性蒙脱土的制备及其对碘离子的吸附

水体的碘污染问题正日益引起人们的广泛关注。以Swy-2型钠基蒙脱土为载体，利用其层间离子交换特性，简单快速制备了羟基铋离子改性蒙脱土，并通过扫描电镜（SEM）、X射线衍射（XRD）和X射线光电子能谱（XPS）对材料吸附碘前后的物化特性进行了表征，研究了材料对水体中碘离子的去除效果，探讨了相关吸附机理。结果表明：合成材料对碘离子的吸附动力学符合假二级动力学方程，吸附等温线符合Langmuir模型，其最大吸附量为107.5 mg·g-1，换算成氧化铋对碘的吸附量高达595.2mg·g-1；因此，以Swy-2型钠基蒙脱土为载体，进行羟基铋离子改性，可以大大地提高铋利用效果。对吸附碘后材料的XPS和XRD进一步分析推测，羟基铋离子改性蒙脱土对碘离子的去除，可能是经由化学吸附，生成Bi4I2O5所造成的。

Synthesis of hydroxybismuth polycations-impregnated montmorillonite for iodide removal from aqueous solu-tion

Iodide contamination has attracted much public attention in recent years due to its impact on the public health. In this work, hydroxybismuth polycations-impregnated montmorillonite was readily synthesized using Swy-2 Na-montmorillonite as a carrier through ion exchange. Physicochemical properties of the synthesized material before and after adsorption were characterized by SEM, XRD and XPS. Both sorption capacity and kinetics of the synthesized material for iodide removal from water were examined. Model fitting of the sorption equilibrium and kinetics data indicates that iodide sorption by hydroxybismuth polycations-impregnated montmorillonite followed the pseudo-second-order kinetics model and the Langmuir model, showing the material had a maximum adsorption capacity of 107.5 mg·g-1, or equivalent to 595.2 mg·g-1 of Bi2O3. Analysis of the XPS and XRD spectra of post sorption hydroxybismuth polycations-impregnated montmorillonite suggested that iodide adsorption on the material was likely due to chemical sorption of I-1 by forming the insoluble surface species Bi4I2O5.