磁性纳米复合物对水中亚甲基蓝的吸附及其机理

利用正硅酸乙酯水解在磁性纳米锰锌铁氧体表面包裹SiO₂,制备了一种新型“核/壳”结构磁性纳米复合物材料Si-Fe-MNCs.采用N₂-吸附脱附法、透射电子显微镜(TEM)、振动样品磁强计(VSM)和傅利叶变换红外技术(FT-IR)分别对Si-Fe-MNCs的织构性能、形貌和磁性能进行了表征.结果表明,该磁性材料对亚甲基蓝表现出良好的吸附性能,318K时平衡吸附量在40.31~184.1mg/g之间,120min可达吸附平衡,符合准二级动力学方程.吸附过程符合Langmuir等温吸附模型,热力学计算结果表明Si-Fe-MNCs对亚甲基蓝的吸附是以表面物理吸附为主的自发吸热过程,红外结果表明氢键是Si-Fe-MNCs表面官能团与亚甲基蓝之间的主要作用力.Si-Fe-MNCs采用H₂O₂进行再生,5次循环使用后,对MB的平衡吸附量仍可维持在93.64mg/g.

Adsorption and mechanism of methylene blue from water by magnetic nanocomposites

A novel “core/shell” structured magnetic nanocomposite Si-Fe-MNCs was prepared by coating SiO₂ on the surface of Mn-Zn ferrite magnetic nanoparticles (Fe-MNPs) through in-situ hydrolysis of tetraethylorthosilicate (TEOS). The specific surface area, morphology, magnetic properties and surface species of Si-Fe-MNCs were characterized by N₂ -adsorption/desorption, transmission electron microscopy (TEM), vibrating sample magnetometer (VSM) and Fourier transform infrared spectroscopy, respectively. The synthesized magnetic adsorbents exhibited a good performance in the removal of methylene blue (MB) from water, and gave a maximum adsorption capacity of 184.1mg/g at 318K. The adsorption of MB on Si-Fe-MNCs reached equilibrium at 120min, and exhibited the kinetics of pseudo-second-order model according to the Langmuir adsorption isotherms. Additionally, it was found that the adsorption of MB on Si-Fe-MNCs was a spontaneous endothermic physical process according to thermodynamic calculations. FT-IR revealed that MB mainly interacted with the surface functional groups of Si-Fe-MNCs and MB through hydrogen bond. The regeneration of Si-Fe-MNCs after MB adsorption was found to be realized by conducting H₂O₂, and its adsorption capacity could preserve an excellent level of 93.64mg/g after five runs.