Backgroundand Aim. Natural organic matter (NOM) has become one of the most serious environmental problems due to its persistence in aqueous solutions and the risk of carcinogenesis. In this study, the removal efficiencies of real and synthetic humic acid (HA) by multi-walled carbon nanotubes (MWCNTs) coated with iron oxide were evaluated. Materials and Methods. The MWCNs were synthesized and coated with iron oxide. In addition, the effects of pH, contact time, mixing speed, and adsorbent dose on the removal efficiency of NOM by MWCNTs-Fe₃O₄ were studied. Then, the removal efficiency of NOM from real samples was investigated at optimal conditions. The MWCNT-Fe₃O₄ was characterized by scanning electron microscopy (SEM) test and X-ray diffraction (XRD), respectively. Data analysis was performed using Minitab software based on the Taguchi method. Results. The results showed that MWCNTs were coated with Fe₃O₄. The SEM test shows particle (MWCNTs-Fe₃O₄) size in the range of 48–143 nm, and the particles have uniform spherical shapes. Enix software was used to identify the phase in this sample. The conditions including , mixing speed = 120 rpm, adsorbent dosage = 1.5 g·L⁻¹, and contact time = 90 minutes were selected as optimal for NOM adsorption. The mean removal efficiencies of NOM in synthetic samples at 5, 10, and 20 mg·L⁻¹ concentrations were 86.6%, 84.87%, and 95.41%, respectively. In addition, the mean removal efficiency of NOM in Choghakhor Wetland was 77%. Conclusion. Our findings demonstrated that the MWCNTs-Fe₃O₄ can be potentially used as an adsorbent for removing natural organic matter (HA) from aqueous solutions.

中文翻译：

---

用磁性 Fe3O4 纳米粒子修饰多壁碳纳米管去除水溶液中的天然有机物 (NOM)

背景和目标。天然有机物 (NOM) 由于其在水溶液中的持久性和致癌风险，已成为最严重的环境问题之一。在本研究中，评估了涂有氧化铁的多壁碳纳米管 (MWCNT) 对真实和合成腐殖酸 (HA) 的去除效率。材料和方法。合成 MWCN 并涂上氧化铁。此外，研究了pH值、接触时间、混合速度和吸附剂剂量对MWCNTs-Fe ₃ O _{4去除NOM效率的影响。}然后，在最佳条件下研究了实际样品中 NOM 的去除效率。MWCNT-Fe ₃ O ₄分别通过扫描电子显微镜（SEM）测试和X射线衍射（XRD）表征。基于田口方法使用Minitab软件进行数据分析。结果。结果表明，MWCNTs 被Fe ₃ O ₄包覆。SEM测试显示颗粒（MWCNTs-Fe ₃ O ₄）尺寸在48-143 nm范围内，颗粒具有均匀的球形。Enix 软件用于识别该样品中的相。条件包括，混合速度 = 120 rpm，吸附剂用量 = 1.5 g·L ^-1，接触时间 = 90 分钟被选为 NOM 吸附的最佳选择。在 5、10 和 20 mg·L ^-1浓度下，合成样品中 NOM 的平均去除效率分别为 86.6%、84.87% 和 95.41%。此外，Choghakhor 湿地 NOM 的平均去除效率为 77%。结论。我们的研究结果表明，MWCNTs-Fe ₃ O ₄可用作吸附剂，用于从水溶液中去除天然有机物 (HA)。