Microbial extracellular polymeric substance (EPS) is a complex high molecular weight compound secreted from many organisms. In this work, magnetic nanocomposite Fe₃O₄@EPS of Klebsiella sp. J1 were first synthesized for silver ions (Ag⁺) wastewater remediation, which synergistically combined the advantages of the easy separation property of magnetic Fe₃O₄ nanoparticles and the superior adsorption capacity of EPS of Klebsiella sp. J1. The physical and chemical properties of Fe₃O₄@EPS were analyzed comprehensively. Fe₃O₄@EPS exhibited the well-defined core–shell structure (size 50 nm) with high magnetic (79.01 emu g^–1). Batch adsorption experiments revealed that Fe₃O₄@EPS achieved high Ag⁺ adsorption capacity (48 mg g^–1), which was also much higher than many reported adsorbents. The optimal solution pH for Ag⁺ adsorption was around 6.0, with the sorption process followed pseudo-second-order kinetics. Ag⁺ adsorption on Fe₃O₄@EPS was mainly attributed to the reduction of Ag⁺ to silver nanoparticles (AgNPs) by benzenoid amine (−NH−), accompanied by the chelation between Ag⁺ and hydroxyl groups, ion exchange between Ag⁺ and Mg²⁺ and K⁺, and physical electrostatic sorption. The repeated adsorption–desorption experiments showed a good recycle performance of Fe₃O₄@EPS. This study has great importance for demonstrating magnetic Fe₃O₄@EPS as potential adsorbent to remove Ag⁺ from contaminated aquatic systems.

中文翻译：

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核-壳磁性纳米复合材料Fe ₃ O ₄ @微生物细胞外聚合物的合成，用于同时氧化还原吸附和作为银纳米颗粒的银离子的回收。

微生物细胞外聚合物（EPS）是一种从许多生物体中分泌出来的复杂的高分子量化合物。在这项工作中，Klebsiella sp。的磁性纳米复合Fe ₃ O ₄ @EPS 。J1最初是用于银离子（Ag ⁺）废水修复的合成方法，其协同结合了磁性Fe ₃ O ₄纳米颗粒易于分离的特性和Klebsiella sp的EPS优异的吸附能力的优点。J1。全面分析了Fe ₃ O ₄ @EPS的理化性质。铁₃ O ₄@EPS表现出具有高磁性（79.01 emu g ^–1）的明确定义的核-壳结构（尺寸为50 nm ）。批量吸附实验表明，Fe ₃ O ₄ @EPS具有很高的Ag ⁺吸附能力（48 mg g ^–1），也比许多报道的吸附剂要高得多。Ag ⁺吸附的最佳溶液pH值约为6.0，吸附过程遵循拟二级动力学。Ag ⁺在Fe ₃ O ₄ @EPS上的吸附主要归因于苯甲胺（-NH-）将Ag ⁺还原为银纳米颗粒（AgNPs），并伴随Ag ⁺之间的螯合和羟基，Ag ⁺和Mg ²⁺和K ⁺之间的离子交换以及物理静电吸附。重复的吸附-解吸实验表明，Fe ₃ O ₄ @EPS具有良好的循环性能。这项研究对于证明磁性Fe ₃ O ₄ @EPS作为潜在的吸附剂从受污染的水生系统中去除Ag ⁺具有重要意义。