| 超顺磁性纳米Fe3O4@SiO2功能化材料对镉的吸附机制 |
| 摘要点击 2448 全文点击 717 投稿时间：2020-10-03 修订日期：2020-11-27 |
| 查看HTML全文
查看全文 查看/发表评论 下载PDF阅读器 |
| 中文关键词 镉污染 磁性纳米Fe3O4@SiO2功能化材料(MFS) Cd2+ 吸附 机制 |
| 英文关键词 cadmium pollution superparamagnetic nano-Fe3O4@SiO2 functionalized materials (MFS) Cd2+ adsorption mechanism |
|
| 中文摘要 |
| 含镉废水的处理对于重金属镉的排放控制具有重要的意义.通过共沉淀法制备出了超顺磁性纳米Fe3O4@SiO2功能化材料（MFS），采用等温吸附实验和动力学实验方法研究了MFS对Cd2+的吸附热力学和动力学特征，并借助BET、XRD和SEM等结构表征研究了MFS对Cd2+吸附过程及机制.结果表明，MFS对Cd2+有较好的吸附效果，Langmuir方程能极好地描述吸附等温特征，最大吸附容量值为69.49 mg·kg-1；吸附反应的自由能变ΔG、焓变ΔH和熵变ΔS表明MFS材料对Cd2+的吸附是自发、吸热和熵增的过程；反应体系最佳初始pH为7；溶液中的Mg2+、SO42-、Ca2+和NO3-这4种干扰离子对吸附反应存在一定的抑制作用；拟二级动力学模型表明MFS对Cd2+的吸附过程分为快速的外扩散阶段与缓慢的内扩散阶段；MFS吸附Cd2+后经洗脱再生，材料重复使用3次后对Cd2+去除率仍达73%以上.BET、XRD、FTIR和VSM结构表征表明SiO2成功修饰在Fe3O4表面，MFS主要成球状，平均粒径为38.7 nm，饱和磁化强度为85.38 emu·g-1；XRD、EDS和XPS图谱揭示Cd2+被成功吸附到材料上，主要机制为Cd2+与材料表面的—OH发生配位反应. |
| 英文摘要 |
| The treatment of cadmium-containing wastewater is of great significance for the emission control of the heavy metal cadmium. Here, a superparamagnetic nano-Fe3O4@SiO2 functionalized material (MFS) was prepared via a co-precipitation method, and the adsorption thermodynamic and kinetic characteristics of Cd2+ were studied by isothermal adsorption tests and kinetic experiments. The adsorption process and mechanism of MFS with respect to Cd2+ were also studied using BET, XRD, and SEM. The Langmuir equation well described the isothermal adsorption characteristics of MFS, and the maximum adsorption capacity was 69.49 mg·g-1. The standard free energy (ΔG), enthalpy (ΔH), and entropy changes (ΔS) showed that the adsorption reaction was a spontaneous, endothermic, and entropic process. The optimal initial pH of the adsorption reaction was 7. The four interfering ions (Mg2+, SO42-, Ca2+, and NO3-) in the solution had a certain inhibitory effect on the adsorption reaction. The pseudo-second-order kinetic model showed that the adsorption process of Cd2+ was divided into two stages, namely a rapid external diffusion stage and a slow internal diffusion stage. The removal rate of Cd2+ was still>73% after using the MFS three times. The BET, XRD, FTIR, and VSM analyses showed that SiO2 was successfully modified on the Fe3O4 surface. MFS is mainly spherical in structure with an average particle size of 38.7 nm and has a saturated magnetic intensity of 85.38 emu·g-1. The XRD, EDS, and XPS analyses revealed that Cd2+ was successfully adsorbed by the material, and the main mechanism was the coordination reaction between Cd2+ and -OH on the surface of the material. |
|
|
|
