Abstract:

The sea urchin magnetic nano-Fe₃O₄@TiO₂ particles (SUMNPs) with core-shell structure were prepared by sol-gel technique combined with hydrothermal method. The morphologies and surface areas of SUMNPs were characterized by methods such as TEM and SEM. It was confirmed that the sea-urchin magnetic nanomaterial exhibit Fe₃O₄ microsphere as core and TiO₂ as shell, the diameter of the particles is about 400 nm, the specific surface area is 236.082 m²·g^-1, and the surface pore size is about 6.274 nm. The adsorption on heavy metal ions showed that, based on the Pb²⁺ ion radius is large and the layers of elections is more, in the mixed system of Pb²⁺, Cd²⁺, Cu²⁺, Zn²⁺ and Ni²⁺, SUMNPs could adsorb Pb²⁺ with high capacity and high selectivity, and almost no adsorption of other four heavy metal ions. The single Pb²⁺ adsorption could be fast equilibrium in 5 min and the equilibrium adsorption capacity was 283 mg·g^-1. The adsorption process is in accordance with the Langmuir isothermal adsorption model, and the saturated adsorption capacity is up to 458.72 mg·g^-1. After desorbed and regenerated by EDTA disodium and NaOH, SUMNPs can be reused more than 8 times. In summary, SUMNPs have excellent selectivity for Pb²⁺, and have good application prospect in the treatment of pollution and restoration of water ecological environment.

Key words: hydrothermal synthesis, magnetic nanoparticles, porous media, heavy metal adsorption, thermodynamic properties

摘要：

耦合溶胶-凝胶技术与水热法，制备具有核壳结构的海胆状Fe₃O₄@TiO₂磁性纳米介质（sea urchin magnetic nanoparticles，SUMNPs）。采用TEM、SEM等方法对SUMNPs的形貌等性质进行表征，证实该材料呈现出以Fe₃O₄为核，以TiO₂为壳的海胆状结构，壳层直径约400 nm，比表面积高达236.082 m²·g^-1，表面孔径约6.274 nm。SUMNPs对重金属离子选择吸附的结果表明，基于Pb²⁺离子半径大、电子层数多等物化特点，在Pb²⁺、Cu²⁺、Ni²⁺、Zn²⁺、Cd²⁺ 5种金属离子混合体系中，SUMNPs可以高容量、高选择性快速吸附Pb²⁺，而对其他4种重金属离子几乎无吸附活性。单一Pb²⁺吸附可在5 min内快速平衡，平衡吸附容量为283 mg·g^-1。吸附过程符合Langmuir等温吸附模型，SUMNPs对Pb²⁺的最大饱和吸附容量为458.72 mg·g^-1。经EDTA二钠解吸，NaOH再生后的SUNMPs可以重复使用8次以上。SUMNPs对Pb²⁺具备优异的选择性吸附性能，在处理水体铅污染、恢复水体生态领域具有良好的应用前景。

关键词: 水热合成, 磁性纳米粒子, 多孔介质, 重金属吸附, 热力学性质