双功能化磁性纳米修复剂对多重金属的快速、高效钝化行为

采用“一锅法”制备了四氧化三铁/半胱氨酸（Fe₃O₄/Cys）磁性纳米微球，随后对Fe₃O₄/Cys进行亚氨基二乙酸（IDA）修饰得到Fe₃O₄/Cys/IDA磁性双功能化纳米微球。研究发现Fe₃O₄/Cys中的L-Cys是通过—SH基团接枝到Fe₃O₄表面的，随后IDA分子中的羧基与Fe₃O₄/Cys中的—NH₂形成酰胺键，最终形成多支链多羧基的Fe₃O₄/Cys/IDA磁性纳米修复剂。基于修复剂表面短支链-长支链交替的多羧基结构，实现了羧基基团的高密度接枝。同时，Fe₃O₄/Cys/IDA磁性纳米微球对Pb²⁺、Cd²⁺、Cu²⁺、Co²⁺、Ni²⁺、Zn²⁺为专性吸附，而对Hg²⁺属于非专性吸附，且吸附重金属后得到的钝化产物均表现了良好的稳定性。另外，Fe₃O₄/Cys/IDA对重金属离子的吸附符合Langmuir模型，属于单层均相吸附，其吸附过程符合准二级动力学模型，最大吸附量为49.05 mg·g^-1。

Fast and Efficient Immobilization Behavior of Bifunctional Magnetic Nano-Amendment Against Multi-heavy Metal

Ferroferric oxide/L-cysteine (Fe₃O₄/Cys) magnetic nanospheres were synthesized by one pot method. Subsequently, the obtained Fe₃O₄/Cys were further modified by conjugating iminodiacetic acid (IDA) to obtain Fe₃O₄/Cys/IDA nanospheres. It was indicated that L-Cys was grafted on the surface of Fe₃O₄ by -SH group and Fe₃O₄/Cys/IDA, with more branched chains and more -COOH groups, was obtained by amido bond formed by the -NH₂ group of Fe₃O₄/Cys and the -COOH group of IDA. Due to the alternative short and long chains grafting, Fe₃O₄/Cys/IDA nanospheres displayed high density modification of -COOH groups. Meanwhile, we found that the adsorption of Pb²⁺, Cd²⁺, Cu²⁺, Co²⁺, Ni²⁺, Zn²⁺ ions by Fe₃O₄/Cys/IDA nanospheres were specific adsorption and that of Hg²⁺ ions was unspecific adsorption. And all the complexes (Fe₃O₄/Cys/IDA-M, M was the metal) obtained after immobilization exhibited good stability. Experimental equilibrium data were also analyzed by the Langmuir and Freundlich models, and the best fit was obtained with the Langmuir isotherm equation, which was monolayer homogeneous adsorption. The kinetic study indicated that the adsorption kinetic data was well described by the pseudo-second kinetic model and the maximum immobilization capacity was 49.05 mg·g^-1, which was a fast and efficient heavy metal immoblization material.