Low-cost adsorbents derived from agricultural by-products incorporated magnetic nanoparticles (NPs) are promising and novel adsorbents for water/wastewater treatment due to their outstanding performance and easy separation. This study reports a nanocomposite of cobalt superparamagnetic (CoFe ₂O₄) NPs incorporated biopolymers extracted from a dragon fruit (hylocereus undatus) peel, called bp-CoFe ₂O₄, to potentially remove Ni(II) ions from aqueous solutions. Morphologic and structural properties of the bp-CoFe ₂O₄ were successfully characterized using a scanning electron spectrometry, X-ray diffraction, Fourier transform infrared spectrometry, and vibrating sample magnetometer (VSM). The bp-CoFe ₂O₄ particles exhibited soft and superparamagnetic properties, which can be easily recycled using an external magnet. Ni(II) adsorption on the bp-CoFe₂O₄ was attributed to both the components including CoFe₂O₄ particles and coated biopolymers. Indeed, the bp-CoFe₂O₄ adsorbing Ni(II) ions reached optimal at pH $\sim$6 ($\sim$88% of Ni(II) removal at an adsorbent dose of 1 g/L and Ni(II) concentration of 171.1 mg/L). The bp-CoFe ₂O₄ can maintain the effective treatment of Ni(II) ion (only $\sim$10% of efficiency loss) up to three cycles of the regeneration. Owing to retaining the magnetic property through the regeneration cycles, this bio-adsorbent would promise a high potential for long-term treatment of Ni(II) ions from polluted waters with easy separation.

源自农业副产品的低成本吸附剂结合了磁性纳米粒子 (NPs)，由于其优异的性能和易于分离，因此是用于水/废水处理的有前途的新型吸附剂。这项研究报告了钴超顺磁性 (CoFe ₂ O ₄ ) NPs纳米复合材料从火龙果 ( hylocereus undatus ) 果皮中提取的生物聚合物，称为 bp-CoFe ₂ O ₄，有可能从水溶液中去除 Ni(II) 离子。bp-CoFe ₂ O _{4 的}形态和结构特性使用扫描电子能谱、X 射线衍射、傅里叶变换红外光谱和振动样品磁强计 (VSM) 成功表征。bp-CoFe ₂ O ₄颗粒表现出柔软和超顺磁性的特性，可以使用外部磁铁轻松回收。Ni(II)在bp-CoFe ₂ O ₄上的吸附归因于包括CoFe ₂ O ₄颗粒和涂覆的生物聚合物的两种组分。事实上，bp-CoFe ₂ O ₄吸附 Ni(II) 离子在 pH 值下达到最佳$～$6 ($～$在 1 g/L 的吸附剂剂量和 171.1 mg/L 的 Ni(II) 浓度下，88% 的 Ni(II) 去除率。bp-CoFe ₂ O ₄可以保持对 Ni(II) 离子的有效处理（仅$～$10% 的效率损失）最多三个循环的再生。由于通过再生循环保持磁性，这种生物吸附剂有望长期处理污染水中的 Ni(II) 离子，并且易于分离。