In the present work, the hollow MgO spheres were synthesized through a facile wet-chemistry method. X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and energy dispersive spectrum are employed to characterize the as-prepared sample. Those results indicate that the average size of the as-prepared MgO hollow spheres is about 2 μm. Also, the MgO hollow spheres have the polycrystalline and porous structure, which would provide large specific surface area and plenty active sites for fluoride adsorption. The adsorption properties of the MgO hollow spheres towards fluoride are investigated. The fluoride adsorption kinetics of the MgO hollow spheres fits well the pseudo-second-order model. Also, the kinetic data revealed that the fluoride adsorption was rapid, more than 83% of fluoride could be removed within 40 min. The fluoride adsorption capacity of the hollow MgO spheres is larger than 182.4 mg/g at a pH of 7.0. The as-prepared products maintain excellent adsorption performance in the pH range of 3–11. In addition, the adsorption mechanism also has been discussed. From the FTIR results, a hydroxyl and carbonate coexchange mechanism is proposed. It is believed that the hollow MgO spheres are a potential candidate for fluoride removal.

中文翻译：

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MgO空心球的简易合成及其氟化物吸附性能

在目前的工作中，空心 MgO 球体是通过简单的湿化学方法合成的。X 射线衍射、扫描电子显微镜、透射电子显微镜和能量色散光谱用于表征所制备的样品。这些结果表明所制备的 MgO 空心球的平均尺寸约为 2  μ米。此外，MgO空心球具有多晶和多孔结构，这将为氟化物吸附提供大的比表面积和大量的活性位点。研究了MgO空心球对氟化物的吸附性能。MgO 空心球的氟化物吸附动力学符合准二级模型。此外，动力学数据显示氟化物吸附迅速，可在 40 分钟内去除 83% 以上的氟化物。在 pH 值为 7.0 时，空心 MgO 球的氟化物吸附容量大于 182.4 mg/g。所制备的产品在 3-11 的 pH 范围内保持优异的吸附性能。此外，还讨论了吸附机理。根据 FTIR 结果，提出了羟基和碳酸酯的共交换机制。