MIL-101(Cr) has demonstrated promising potential for tetracycline (TC) adsorption owing to its exceptional water stability. In this study, polymers with nitrogenous organic ligands were incorporated in the framework of MIL-101(Cr) using a post-synthetic modification approach to enhance the adsorption properties of MIL-101(Cr) for TC. We used the grafting reagent 4-aminopyridine (4-Apy), which contains two types of nitrogen species (amino nitrogen and pyridine nitrogen), to create a series of stable MOF composite materials, xApy-MIL-101(Cr), through interaction with the exposed Cr(III) sites in MIL-101(Cr). The high nitrogenous organic ligand content in the framework of xApy-MIL-101(Cr) contributes to its high TC adsorption capacity. The results showed that 30%Apy-MIL-101(Cr) adsorbed far more than MIL-101(Cr), reaching a maximum adsorbed amount of 264.5 mg g⁻¹, nearly five times greater. Importantly, adsorption equilibrium can be reached within 50 minutes. Moreover, the primary adsorption mechanisms of xApy-MIL-101(Cr) for TC removal involve hydrogen bonding, π–π interactions, and electrostatic interactions. Additionally, 30%Apy-MIL-101(Cr) demonstrated excellent adsorption cycle stability, maintaining a regeneration rate of 74% even after four cycles of TC adsorption and desorption.

中文翻译：

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氨基氮和吡啶氮对氨基吡啶修饰的MIL-101(Cr)四环素吸附的联合作用


MIL-101(Cr) 由于其卓越的水稳定性而在四环素 (TC) 吸附方面表现出良好的潜力。在本研究中，采用合成后改性方法将具有含氮有机配体的聚合物纳入MIL-101(Cr)的框架中，以增强MIL-101(Cr)对TC的吸附性能。我们使用含有两种氮物种（氨基氮和吡啶氮）的接枝剂4-氨基吡啶（4-Apy），通过相互作用创建了一系列稳定的MOF复合材料xApy-MIL-101（Cr）与 MIL-101(Cr) 中暴露的 Cr(III) 位点。 xApy-MIL-101(Cr)框架中的高含氮有机配体含量有助于其高TC吸附能力。结果表明，30%Apy-MIL-101(Cr)的吸附量远高于MIL-101(Cr)，最大吸附量达到264.5 mg·g ⁻¹ ，接近5倍。重要的是，吸附平衡可以在 50 分钟内达到。此外，xApy-MIL-101(Cr)去除TC的主要吸附机制包括氢键、π-π相互作用和静电相互作用。此外，30%Apy-MIL-101(Cr)表现出优异的吸附循环稳定性，即使在四次TC吸附和解吸循环后仍保持74%的再生率。