A new nanoadsorbent was synthesized through intercalation of thioglycolic acid (TGA) in the magnetic layered double hydroxide nanocomposite (Fe₃O₄/Zn–Fe LDH/TGA) and used for the removal of heavy metal ions such as Hg²⁺ and Pb²⁺ from aqueous solutions. The morphology and structure of the synthesized nanoadsorbent were investigated by Fourier transform infrared spectroscopy, X-ray diffraction, field-emission scanning electron microscopy and transmission electron microscopy. Also, the quantitative measurements of metal ions were determined using atomic fluorescence spectroscopy. The simultaneous impact of important parameters on the Hg²⁺ removal including pH, adsorbent dosage and removal time were investigated using response surface methodology. Based on the obtained results, pH 5.5 was achieved, and also 9 mg as adsorbent dosage and 30 min for removal time were selected as optimum conditions in Hg²⁺ removal experiments. The adsorption kinetic results fitted well with the pseudo-second-order model, and the R² value = 0.991 while the estimated q_e was matched well with the experimental data. Thermodynamic results showed that the adsorption process of Hg²⁺ was endothermic, feasible and spontaneous. Also, the efficiency of the magnetic nanocomposite was investigated for adsorption of the metal ions. The selectivity experiments showed the following order: Hg²⁺ ⋙ Pb²⁺ > Fe²⁺ > Cu²⁺ > Zn²⁺ > Cd²⁺. Finally, the obtained results verified the excellent ability of the magnetic nanoadsorbent for Hg²⁺ removal from the aqueous media for at least three times recycle with 90% recovery.

中文翻译：

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响应表面法通过硫代乙醇酸修饰的Zn-Fe层双氢氧化物作为磁性可循环吸附剂去除重金属

通过在磁性层状双氢氧化物纳米复合材料（Fe ₃ O ₄ / Zn-Fe LDH / TGA）中插入巯基乙酸（TGA）合成了一种新的纳米吸附剂，并将其用于去除重金属离子，例如Hg ²⁺和Pb ^{2。 +}来自水溶液。通过傅立叶变换红外光谱，X射线衍射，场发射扫描电子显微镜和透射电子显微镜研究了合成的纳米吸附剂的形貌和结构。另外，使用原子荧光光谱法测定金属离子的定量测量。重要参数对Hg ²⁺的同时影响使用响应表面方法研究了包括pH值，吸附剂用量和去除时间在内的去除过程。根据获得的结果，达到pH 5.5，在Hg ²⁺去除实验中，还选择了9 mg作为吸附剂量和30 min的去除时间作为最佳条件。吸附动力学结果与拟二阶模型拟合得很好，R ²值为0.991，而估计的q _e与实验数据吻合良好。热力学结果表明，Hg ²⁺的吸附过程是吸热的，可行的和自发的。此外，研究了磁性纳米复合材料吸附金属离子的效率。选择性实验显示出以下顺序：Hg 2 ⁺  ⋙Pb ²⁺  > Fe ²⁺  > Cu ²⁺  > Zn ²⁺  > Cd ²⁺。最后，获得的结果证实了磁性纳米吸附剂从水介质中脱除Hg ²⁺的出色能力，至少循环了3次，回收率为90％。