Abstract The polydopamine modified with magnetic nanoparticles (Fe3O4@PDA) was prepared and used for Pb2+ removal from aqueous liquids. The resulted Fe3O4@PDA nanocomposite was characterized with Fourier transform infrared spectra (FTIR), vibrating sample magnetometer (VSM), transmission electron microscope (TEM) and X-ray diffraction (XRD). The optimized Pb2+ ions adsorption process was studied by response surface methodology (RSM) considering with 3-variable-3-level Box–Behnken design (BBD). The lead ions adsorption capacity were verified regarding three parameter effects, that is, pH, contact time and initial concentration of Pb2+ ions. The optimal conditions for the lead removal were obtained as 5.8, 5.4 hr and 92 mg/L, for the liquid pH, contact time and the initial lead ions concentration, respectively. Moreover, adsorption isotherms were studied to understand the mechanism of adsorbing Pb2+ ions by Fe3O4@PDA nanocomposite. The models represented the experimental data well. Furthermore, regeneration and reuse of adsorbent for the removal of Pb2+ ion in four cycles was studied. The results show the maximum lead adsorption capacity was 297 mg/g and Fe3O4@PDA nanocomposite could be used as a reusable adsorbent with convenient conditions. HIGHLIGHTS • Polydopamine coated magnetite nanoparticles were used to remove Pb2+ ions. • Lead adsorption process parameters are optimized using Response Surface Method. • The effect of different factors on the adsorption are investigated. • pH shows the greatest effect, time and Pb2+ concentration have significant effect • The adsorption isothermal parameters are studied. • Possible mechanisms of adsorption process have been discussed in detail. GRAPHICAL ABSTRACT

中文翻译：

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使用Box-Behnken设计的磁性Fe3O4@聚多巴胺纳米复合材料从水溶液中去除铅

摘要 制备了磁性纳米粒子修饰的聚多巴胺（Fe3O4@PDA），用于去除水性液体中的Pb2+。通过傅里叶变换红外光谱（FTIR）、振动样品磁强计（VSM）、透射电子显微镜（TEM）和X射线衍射（XRD）对所得Fe3O4@PDA纳米复合材料进行表征。考虑到 3 变量 3 级 Box-Behnken 设计 (BBD)，通过响应面法 (RSM) 研究了优化的 Pb2+ 离子吸附过程。铅离子吸附能力通过三个参数效应进行验证，即 pH、接触时间和 Pb2+ 离子的初始浓度。对于液体 pH 值、接触时间和初始铅离子浓度，最佳脱铅条件分别为 5.8、5.4 小时和 92 毫克/升。而且，研究了吸附等温线，以了解 Fe3O4@PDA 纳米复合材料吸附 Pb2+ 离子的机制。模型很好地代表了实验数据。此外，研究了吸附剂的再生和再利用以在四个循环中去除 Pb2+ 离子。结果表明，最大的铅吸附容量为 297 mg/g，Fe3O4@PDA 纳米复合材料在条件方便的情况下可用作可重复使用的吸附剂。亮点 • 聚多巴胺涂层磁铁矿纳米颗粒用于去除 Pb2+ 离子。• 使用响应面法优化铅吸附工艺参数。• 研究了不同因素对吸附的影响。• pH 显示出最大的影响，时间和 Pb2+ 浓度有显着影响 • 研究了吸附等温参数。• 详细讨论了吸附过程的可能机制。图形概要