1.Nanjing University;2.Nanjing Innovation Center for Environmental Protection Industry Co. Ltd;3.Nanjing Huachuang Institute of Environmental Technology Co. Ltd
National Natural Science Foundation of China (No. 51378253), Postdoctoral Science Foundation of Jiangsu Province (2020Z299), China Postdoctoral Science Foundation (2020M671443)
优选二乙烯三胺(DETA)作为胺化试剂对聚丙烯腈(PAN)纳米纤维进行改性，制备多胺纳米纤维吸附剂D-PAN，探究对Pb(Ⅱ)的吸附特性与机制。文章对D-PAN进行SEM、BET、FTIR和XPS表征，并通过实验研究溶液初始pH、接触时间、温度、无机盐等因素对D-PAN吸附过程的影响。结果表明：多胺基团被成功引入D-PAN的三维网络中，多孔道结构有利于改善D-PAN对Pb(Ⅱ)的吸附性能。pH=5.0时D-PAN对Pb(Ⅱ)的静态吸附性能最优，由Langmuir模型拟合获得的最大吸附容量高达1.73 mmol/g，准一级动力学速率常数高达0.06 min-1。含盐体系中D-PAN对Pb(Ⅱ)的吸附量可提高近1倍，“盐促”效应显著。结合XPS和DFT结果分析，多胺基团中N原子可与Pb(Ⅱ)形成双齿和三齿螯合物。多次再生利用性能显示D-PAN结构性能具有优良的稳定性。可见，D-PAN具有吸附快、容量大、易再生等优点，具有广阔应用前景。
For the preparation of an ideal material for the emergency disposal of Pb(Ⅱ) contaminated water, polyacrylonitrile was selected as the matrix to be chemically modified with diethylenetriamine (DETA), and a kind of polyamine chelating nanofiber (D-PAN) has been successfully prepared. The physical and chemical structure analysis by SEM, BET, FTIR and XPS was performed. Amine groups was successfully introduced into three-dimensional network of intertwined fiber filaments which enhanced the adsorption capacity. It had the best adsorption performance at pH 5.0. The adsorption equilibrium could be reached within 2 h with an adsorption rate constant 0.06 min-1. The maximum adsorption capacity was 1.73 mmol/g obtained by fitting with Langmuir model. Moreover, D-PAN had a significant "salt-promoting" effect, and the adsorption amount of Pb (II) in the salt-containing system could be nearly doubled. Combining the results of XPS and DFT, it was found that Pb(Ⅱ) could be removed by chelating with N atoms in polyamine groups to form bidentate and tridentate complexes. Furthermore, D-PAN exhibited excellent structural stability after multiple regeneration. In summary, D-PAN has the advantages of fast adsorption, large capacity and easy regeneration, and has broad application prospects in the field of Pb (Ⅱ) polluted water remediation.