支化聚乙烯亚胺功能化磁性纳米吸附剂的制备及对Cu2+的吸附研究

为解决水体中重金属Cu²⁺污染，本研究首先采用水热法制备得到超顺磁四氧化三铁纳米粒子，然后使用对Cu²⁺具有强络合作用的含有丰富氨基官能团的支化聚乙烯亚胺接枝到纳米粒子表面，得到Fe₃O₄@BPEI磁性纳米吸附剂。采用红外光谱（FTIR）、X射线粉末衍射（XRD）、透射电子显微镜（TEM）等对其结构、尺寸及形貌进行表征。研究了不同吸附因素对吸附剂吸附Cu²⁺的影响，确定了最佳吸附条件，并通过吸附动力学模型和吸附等温线模型进一步探讨吸附机理。结果表明：支化聚乙烯亚胺成功接枝到四氧化三铁纳米粒子表面。最佳吸附条件为pH=6.0、吸附平衡时间为40 min、吸附剂用量为10 mg。通过实验数据拟合，Fe₃O₄@PEI吸附Cu²⁺的过程符合Langmuir等温吸附方程和拟二级动力学模型，表明吸附过程为化学吸附控制的单分子层覆盖，在303 K时，模型理论饱和吸附量为141.24 mg/g。表明支化聚乙烯亚胺修饰的磁性纳米吸附剂对Cu²⁺具有较强的吸附能力，对水体中Cu²⁺的去除具有一定的应用前景。

Preparation of Branched Polyethyleneimine Functionalized Magnetic Nano-adsorbents for Cu2+and It's Adsorption Properties

In order to solve the water contamination arises from heavy metal Cu²⁺, magnetic nano-adsorbent Fe₃O₄@BPEI was prepared in two steps. The first one was the preparation of superparamagnetic Fe₃O₄ nanoparticles by the hydrothermal method, and the second one is the grafting of branched polyethyleneimine (BPEI), which contains rich amine group functional groups and has a strong complexation ability to Cu²⁺, onto the surface of the Fe₃O₄ nanoparticles. The structure, size and morphology were characterized by infrared spectroscopy (FTIR), X-ray powder diffraction (XRD) and transmission electron microscopy (TEM). The effects of solution pH, time, adsorbent dosage, temperature and initial concentrations of metal ions on the adsorption of Cu²⁺ were studied, and the optimal adsorption conditions were determined. The adsorption mechanism was further discussed by adsorption kinetics models and adsorption isotherm models. The results showed that BPEI was successfully grafted onto the surface of Fe₃O₄ nanoparticles. The optimal adsorption conditions were obtained: pH=6.0, adsorption equilibrium time was 40 min and the adsorbent dosage was 10 mg. The adsorption behavior of Fe₃O₄@PEI complies with the second-order kinetic model and the Langmuir isothermal model, which indicates that the adsorption process of Cu²⁺ by Fe₃O₄@PEI is monolayer coverage, and is controlled by chemical interactions. The theoretical saturation adsorption capacity of the model is 141.24 mg/g at 303 K. The results show that the magnetic nano-adsorbent modified by branched polyethylene imine is an efficient adsorbent for the adsorption of Cu²⁺ from aqueous solution, and has a certain application prospect.