The presence of Mn(II) in water exceeding the permitted concentration limits declared by the World Health Organization (WHO) influences individuals, animals, and the ecosystem negatively. Therefore, there is a necessity for an efficient material to eliminate this potentially toxic element from wastewater. We herein focused on the adsorptive removal of Mn(II) ions from polluted aqueous media using natural Egyptian glauconite clay (G) and its nanocomposites with modified chitosan (CS). We applied modified chitosan with glutaraldehyde (GL), ethylenediaminetetraacetic acid (EDTA), sodium dodecyl sulfate (SDS), and cetyltrimethyl ammonium bromide (CTAB). The utilized nanocomposites were referred to as GL-CS/G, EDTA-GL-CS/G, SDS-CS/G, and CTAB-CS/G, respectively. The point of zero charge values of the materials were estimated. The adsorption properties of the G clay and its nanocomposites toward the removal of Mn(II) ions from polluted aqueous media as well as the adsorption mechanism were explored using a batch technique. The glauconite (G) and its nanocomposites: GL-CS/G, CTAB-CS/G, EDTA-GL-CS/G, and SDS-CS/G, exhibited maximum adsorption capacity values of 3.60, 24.0, 26.0, 27.0, and 27.9 mg g⁻¹, respectively. The adsorption results fitted well the Langmuir isotherm and pseudo-second-order kinetic models. The estimated thermodynamic parameters: ΔH° (from 1.03 to 5.55 kJ/mol) and ΔG° (from − 14.5 to − 18.8 kJ/mol), indicated that Mn(II) ion adsorption process was endothermic, spontaneous, and physisorption controlled. Furthermore, the obtained adsorption results are encouraging and revealing a great potentiality for using the modified adsorbents as accessible adsorbents for Mn(II) ion removal from polluted aqueous solutions, depending on their reusability, high stability, and good adsorption capacities.

Graphic Abstract

中文翻译：

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海绿石粘土功能化壳聚糖纳米复合材料吸附去除污染水介质中的锰离子

水中 Mn(II) 的含量超过世界卫生组织 (WHO) 宣布的允许浓度限值，会对个人、动物和生态系统产生负面影响。因此，需要一种有效的材料来消除废水中的这种潜在有毒元素。我们在此专注于使用天然埃及海绿石粘土 (G) 及其与改性壳聚糖 (CS) 的纳米复合材料从污染的水性介质中吸附去除 Mn(II) 离子。我们应用了含有戊二醛 (GL)、乙二胺四乙酸 (EDTA)、十二烷基硫酸钠 (SDS) 和十六烷基三甲基溴化铵 (CTAB) 的改性壳聚糖。所使用的纳米复合材料分别称为 GL-CS/G、EDTA-GL-CS/G、SDS-CS/G 和 CTAB-CS/G。估计材料的零电荷值点。使用分批技术探索了 G 粘土及其纳米复合材料从污染的水介质中去除 Mn(II) 离子的吸附性能以及吸附机制。海绿石 (G) 及其纳米复合材料：GL-CS/G、CTAB-CS/G、EDTA-GL-CS/G 和 SDS-CS/G，表现出的最大吸附容量值为 3.60、24.0、26.0、27.0，和 27.9 毫克克^-1，分别。吸附结果符合朗缪尔等温线和准二级动力学模型。估计的热力学参数：ΔH°（从 1.03 到 5.55 kJ/mol）和 ΔG°（从 - 14.5 到 - 18.8 kJ/mol）表明 Mn(II) 离子吸附过程是吸热、自发和物理吸附控制的。此外，所获得的吸附结果令人鼓舞，并揭示了将改性吸附剂用作从污染水溶液中去除 Mn(II) 离子的可接近吸附剂的巨大潜力，这取决于它们的可重复使用性、高稳定性和良好的吸附能力。

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