Nitrite is one of the main pollutants in the water worldwide. In this study, we have applied the reverse suspension crosslinking methodology based on chitosan (CS) and Fe₃O₄ (FeO) to synthesize the novel magnetic nanomaterial of chitosan (CS-FeO). The physical and chemical properties of CS-FeO were further characterized by scanning electron microscopy, particle size distribution, thermogravimetry, fluxgate magnetometer, Fourier transform infrared spectroscopy, X-ray diffraction spectroscopy, and energy dispersive spectroscopy. Results revealed that CS-FeO showed high thermal stability in the temperature ranging from 50 to 200°C. CS-FeO showed high crystallinity and magnetism and was easily and quickly separated from aqueous solution in the presence of an external magnetic field. The molecular structure of CS-FeO showed that the core-shell structure of CS-FeO was established with FeO as the core and CS as the shell. Furthermore, the adsorption rate of nitrite by CS-FeO reached under optimal conditions. Moreover, CS-FeO showed high regeneration capability with Na₂SO₄ used as the eluent. Our study demonstrated evidently that CS-FeO can be potentially used to remove nitrite from drinking water sources and industrial wastewater, suggesting the promising future of the application of CS-derived magnetic nanomaterials in the areas of environmental protections.

中文翻译：

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壳聚糖衍生磁性纳米材料：合成、表征和水中亚硝酸盐吸附

亚硝酸盐是世界范围内水中的主要污染物之一。在本研究中，我们应用了基于壳聚糖 (CS) 和 Fe ₃ O ₄的反向悬浮交联方法(FeO) 合成新型壳聚糖磁性纳米材料 (CS-FeO)。通过扫描电子显微镜、粒度分布、热重法、磁通门磁强计、傅里叶变换红外光谱、X射线衍射光谱和能量色散光谱进一步表征了CS-FeO的物理和化学性质。结果表明，CS-FeO 在 50 至 200°C 的温度范围内表现出较高的热稳定性。CS-FeO 表现出高结晶度和磁性，在外部磁场存在的情况下可以轻松快速地从水溶液中分离出来。CS-FeO的分子结构表明，CS-FeO的核壳结构是以FeO为核，CS为壳。此外，CS-FeO对亚硝酸盐的吸附率达到在最佳条件下。此外，CS-FeO 显示出高再生能力，Na ₂ SO ₄用作洗脱液。我们的研究表明，CS-FeO 可潜在地用于去除饮用水源和工业废水中的亚硝酸盐，表明 CS 衍生的磁性纳米材料在环境保护领域的应用前景广阔。