Magnetic Fe₃O₄ nanoparticles with an average diameter of 64 nm was synthesized solvothermically and subsequently modified with melamine-based dendrimer amine (MDA–Fe₃O₄) via grafting method. The synthesized materials were characterized using DLS, SEM, XRD, FTIR, VSM, TGA and elemental analysis techniques. The MDA–Fe₃O₄ was employed for the efficient removal of Pb(II) ions from an aqueous solution. The adsorption efficiency was investigated in relation to the independent variables of Pb(II) concentration (80–250 mg L⁻¹), pH of the solution (3–7), adsorbent dosage (0.1–0.5 g L⁻¹) and temperature (10–40 °C) via a central composite design (CCD) using response surface methodology (RSM). The significance of independent variables and their interactions was tested using ANOVA at a 95% confidence limit (α = 0.05). A second-order quadratic model was established to predict the adsorption efficiency. Under the optimum condition (initial Pb(II) concentration = 110 mg L⁻¹, MDA-Fe₃O₄ dosage = 0.49 g L⁻¹, pH = 5 and temperature = 30 °C) a removal percentage of 85.6% was obtained. The isotherm data fitted well to the Freundlich model within the concentration range of the experimental study. A maximum adsorption capacity of 333.3 mg g⁻¹ was predicted by the Langmuir model. The adsorption rate of Pb(II) ions onto MDA–Fe₃O₄ was in good agreement with the pseudo-second-order model (R² = 0.999; k₂ = 4.7 × 10⁻⁴ g mg⁻¹min⁻¹). Thermodynamically, adsorption was spontaneous and endothermic. The MDA–Fe₃O₄ was successfully regenerated using 0.3 M HCl with little loss of adsorption capacity (≈7%) for five successive adsorption cycles.

中文翻译：

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基于三聚氰胺的树枝状大分子胺改性的磁性纳米粒子作为废水处理的有效Pb（II）吸附剂：通过响应面法进行吸附优化

溶剂热法合成了平均直径为64 nm的磁性Fe ₃ O ₄纳米粒子，然后通过接枝方法用基于三聚氰胺的树状大分子胺（MDA–Fe ₃ O ₄）进行了改性。使用DLS，SEM，XRD，FTIR，VSM，TGA和元素分析技术对合成材料进行了表征。MDA-Fe ₃ O ₄用于从水溶液中有效去除Pb（II）离子。研究了与Pb（II）浓度（80–250 mg L ^-1），溶液的pH（3–7），吸附剂剂量（0.1–0.5 g L ^-1）的独立变量有关的吸附效率）和温度（10–40°C），通过使用响应面方法（RSM）的中央复合设计（CCD）。使用ANOVA在95％置信限（α  = 0.05）下测试了自变量及其相互作用的显着性。建立了一个二次方模型来预测吸附效率。在最佳条件下（初始Pb（II）浓度= 110 mg L ^-1，MDA-Fe ₃ O ₄剂量= 0.49 g L ^-1，pH = 5且温度= 30°C），去除率为85.6％。 。在实验研究的浓度范围内，等温线数据非常适合Freundlich模型。最大吸附容量为333.3 mg g ^-1由Langmuir模型预测。Pb（II）离子在MDA-Fe ₃ O ₄上的吸附速率与拟二阶模型非常吻合（R ²  = 0.999；k ₂  = 4.7×10 ^-4  g mg ^-1 min ^-1） 。在热力学上，吸附是自发的并且是吸热的。使用0.3 M HCl成功地再生了MDA-Fe ₃ O ₄，连续五个吸附周期几乎没有吸附能力损失（≈7％）。