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 pollutionsuperparamagnetic nano-Fe₃O₄@SiO₂ functionalized materials (MFS)Cd²⁺adsorptionmechanism

作者	单位	E-mail
张立志	西南大学资源环境学院, 重庆 400716 重庆市农业资源与环境研究重点实验室, 重庆 400716	1258237483@qq.com
易平	西南大学资源环境学院, 重庆 400716 重庆市农业资源与环境研究重点实验室, 重庆 400716
方丹丹	西南大学资源环境学院, 重庆 400716 重庆市农业资源与环境研究重点实验室, 重庆 400716
王强	西南大学资源环境学院, 重庆 400716 重庆市农业资源与环境研究重点实验室, 重庆 400716	781216966@qq.com

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⁺、SO₄^2-、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⁺, SO₄^2-, 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.

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