Abstract Novel magnetic microspheres with core-shell structure, Fe3O4@SiO2@MgAl-borate LDH had been fabricated by a facile hydrothermal approach, in which the borate anions intercalated layered double hydroxides (MgAl-borate LDHs) loaded on a SiO2-coated Fe3O4 magnetite core, forming a flower-like hierarchical porous structure constructed by the assembly of ultrathin nanosheets. This composite was characterized via XRD, SEM, TEM, FT-IR, XPS, TG-DSC and VSM. It possessed superparamagnetic property, large specific surface area, moderate pore volume and excellent chemical stability. Benefiting from this unique structure, it exhibited superb adsorption performance. Its maximum adsorption capacities were 158.98 mg g−1 for CR at 298 K with pH=4 and 86.73 mg g−1 for Cr(VI) at 298 K with pH=5, which were larger than most of other similar adsorbent. The adsorption reaction followed the Langmuir model as well as pseudo-second-order rate equation. The higher temperature was in favour of adsorption. The ionic strength showed little effect on the sorption Cr(VI). Furthermore, the possible formation mechanism of this composite and its adsorption mechanism were also proposed. Overall, this new composite is expected to be an excellent adsorbent for CR and Cr (VI) in wastewater due to its superior structural stability, high efficiency, good reusability, and easy collection by magnetic separation.

中文翻译：

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对刚果红和 Cr(VI) 污染物具有优异吸附性能的分级多孔 MgAl-硼酸盐 LDHs 功能化 Fe3O4@SiO2 磁性微球的可行合成

摘要 通过简单的水热法制备了具有核壳结构的新型磁性微球 Fe3O4@SiO2@MgAl-硼酸盐 LDH，其中硼酸盐阴离子嵌入层状双氢氧化物（MgAl-硼酸盐 LDHs）负载在 SiO2 包覆的 Fe3O4 磁铁矿上。核心，形成由超薄纳米片组装构成的花状分层多孔结构。通过 XRD、SEM、TEM、FT-IR、XPS、TG-DSC 和 VSM 对该复合材料进行了表征。它具有超顺磁性、比表面积大、孔容适中和优异的化学稳定性。得益于这种独特的结构，它表现出极好的吸附性能。其最大吸附容量为 298 K、pH=4 的 CR 158.98 mg g-1 和 298 K、pH=5 的 Cr(VI) 86.73 mg g-1，比​​大多数其他类似吸附剂大。吸附反应遵循朗缪尔模型和准二级速率方程。较高的温度有利于吸附。离子强度对吸附 Cr(VI) 的影响很小。此外，还提出了该复合材料的可能形成机制及其吸附机制。总体而言，这种新型复合材料具有优异的结构稳定性、高效率、良好的可重复使用性和易于通过磁分离收集，有望成为废水中 CR 和 Cr (VI) 的优良吸附剂。还提出了该复合材料的可能形成机制及其吸附机制。总体而言，这种新型复合材料具有优异的结构稳定性、高效率、良好的可重复使用性和易于通过磁分离收集，有望成为废水中 CR 和 Cr (VI) 的优良吸附剂。还提出了该复合材料的可能形成机制及其吸附机制。总体而言，这种新型复合材料具有优异的结构稳定性、高效率、良好的可重复使用性和易于通过磁分离收集，有望成为废水中 CR 和 Cr (VI) 的优良吸附剂。