AlSabbagh Hawra A, AlDamestani Kawthar M, Amer Wael A, Iqbal Javed, Lemine O M, Madkhali Nawal, El-Boubbou Kheireddine
Department of Chemistry, College of Science, University of Bahrain, Sakhir 32038, Bahrain.
Department of Chemistry, Faculty of Science, Tanta University, Tanta 31527, Egypt.
Phys Chem Chem Phys. 2025 Aug 20;27(33):17341-17359. doi: 10.1039/d5cp01875g.
The development of novel, selective, and effective nanosorbents that can efficiently eliminate both anionic and cationic organic dyes in wastewater treatment remains a challenge. Herein, we prepared different panels of magnetic nanoparticles (MNPs) coated with various polymers (PVP, PEG, and PAA/starch) and studied their adsorption capacity towards two common dyes: Anionic Congo red (CR) and cationic Methylene blue (MB). The physiochemical, structural, morphological, compositional, and magnetic properties of the polymer-coated MNPs were fully characterized using various electronic and spectroscopic techniques including TEM, XRD, FTIR, and VSM. The obtained polymer-coated MNPs exhibited spherical nanosized particles (∼5-15 nm), pure well-crystallized cubic spinel FeO phases, and high saturation magnetization with superparamagnetic behavior, rendering easy-magnetic separation. The dye removal studies showed that the tailor-made MNPs efficiently adsorb the dyes rapidly (> 99% in less than 2 minutes) with very high adsorption capacities ( = ∼85-110 mg g). Interestingly, it was found that the adsorption is selective where PAA/starch-MNPs were the best at adsorbing the cationic MB, while PEG-MNPs completely removed the anionic CR. Adsorption isotherms and kinetics studies suggest that the adsorption occurs by the Langmuir or Freundlich isothermal adsorption models ( = 0.995) following pseudo-second-order adsorption kinetics ( = 0.999). Thermodynamic data showed that adsorption processes of both CR and MB onto MNPs were endothermic and spontaneous in nature. Moreover, an integrated theoretical density functional theory (DFT) method was employed to fully understand the mechanism behind the dye-adsorbent interactions. DFT studies confirmed that these observations are mainly attributed to strong electrostatic and H-bonding interactions between the grafted functionalized polymer on MNP surface and the specific dye. Delightfully, a regeneration study showed that the magnetic nanoadsorbents could be reused for six consecutive cycles with high removal efficiencies (> 65%), without the use of any desorption agents. These unique findings highlight the potential of the designed polymer-coated MNPs as effective magnetic nanosorbents for quick and efficient industrial wastewater treatment.
开发新型、选择性且有效的纳米吸附剂，以在废水处理中高效去除阴离子和阳离子有机染料仍然是一项挑战。在此，我们制备了涂覆有各种聚合物（聚乙烯吡咯烷酮、聚乙二醇和聚丙烯酸/淀粉）的不同磁性纳米颗粒（MNP）面板，并研究了它们对两种常见染料的吸附能力：阴离子刚果红（CR）和阳离子亚甲基蓝（MB）。使用包括透射电子显微镜（TEM）、X射线衍射（XRD）、傅里叶变换红外光谱（FTIR）和振动样品磁强计（VSM）在内的各种电子和光谱技术，对聚合物包覆的MNP的物理化学、结构、形态、组成和磁性进行了全面表征。所获得的聚合物包覆的MNP呈现出球形纳米颗粒（约5 - 15纳米）、纯的结晶良好的立方尖晶石FeO相，以及具有超顺磁行为的高饱和磁化强度，便于磁分离。染料去除研究表明，定制的MNP能够快速高效地吸附染料（在不到2分钟内> 99%），具有非常高的吸附容量（约85 - 110毫克/克）。有趣的是，发现吸附具有选择性，其中聚丙烯酸/淀粉 - MNP在吸附阳离子MB方面表现最佳，而聚乙二醇 - MNP能完全去除阴离子CR。吸附等温线和动力学研究表明，吸附遵循朗缪尔或弗伦德里希等温吸附模型（R² = 0.995），遵循准二级吸附动力学（R² = 0.999）。热力学数据表明，CR和MB在MNP上的吸附过程本质上是吸热且自发的。此外，采用了综合理论密度泛函理论（DFT）方法来全面理解染料 - 吸附剂相互作用背后的机制。DFT研究证实，这些观察结果主要归因于MNP表面接枝的功能化聚合物与特定染料之间强烈的静电和氢键相互作用。令人高兴的是，再生研究表明，磁性纳米吸附剂可以连续重复使用六个循环，去除效率高（> 65%），无需使用任何解吸剂。这些独特的发现突出了所设计的聚合物包覆的MNP作为有效磁性纳米吸附剂用于快速高效工业废水处理的潜力。
