Kim Yoogyeong, Son Yeongkyun, Bae Sungjun, Kim Tae-Hyun, Hwang Yuhoon
Department of Environmental Engineering, Seoul National University of Science and Technology, Seoul 01811, Korea.
Department of Civil and Environmental Engineering, Konkuk University, Seoul 05029, Korea.
Nanomaterials (Basel). 2022 Apr 18;12(8):1384. doi: 10.3390/nano12081384.
Herein, magnesium/aluminum-layered double hydroxide (MgAl-LDH) and bentonite (BT) nanocomposites (LDH-BT) were prepared by co-precipitation (CP), exfoliation-reassembly (ER), and simple solid-phase hybridization (SP). The prepared LDH-BT nanocomposites were preliminarily characterized by using powder X-ray diffractometry, scanning electron microscopy, and zeta-potentiometry. The chromate adsorption efficacies of the pristine materials (LDH and bentonite) and the as-prepared nanocomposites were investigated. Among the composites, the LDH-BT_SP was found to exhibit the highest chromate removal efficiency of 65.7%. The effect of varying the LDH amount in the LDH-BT composite was further investigated, and a positive relationship between the LDH ratio and chromate removal efficiency was identified. The chromate adsorption by the LDH-BT_SP was performed under various concentrations (isotherm) and contact times (kinetic). The results of the isotherm experiments were well fitted with the Langmuir and Freundlich isotherm model and demonstrate multilayer chromate adsorption by the heterogeneous LDH-BT_SP, with a homogenous distribution of LDH nanoparticles. The mobility of the as-prepared LDH-BT_SP was investigated on a silica sand-filled column to demonstrate that the mobility of the bentonite is dramatically decreased after hybridization with LDH. Furthermore, when the LDH-BT_SP was injected into a box container filled with silica sand to simulate subsurface soil conditions, the chromate removal efficacy was around 43% in 170 min. Thus, it was confirmed that the LDH-BT prepared by solid-phase hybridization is a practical clay-based nanocomposite for in situ soil and groundwater remediation.
在此，通过共沉淀法（CP）、剥离-重组法（ER）和简单的固相杂化法（SP）制备了镁/铝层状双氢氧化物（MgAl-LDH）和膨润土（BT）纳米复合材料（LDH-BT）。使用粉末X射线衍射仪、扫描电子显微镜和ζ电位分析法对制备的LDH-BT纳米复合材料进行了初步表征。研究了原始材料（LDH和膨润土）以及所制备的纳米复合材料对铬酸盐的吸附效果。在这些复合材料中，发现LDH-BT_SP表现出最高的铬酸盐去除效率，为65.7%。进一步研究了改变LDH-BT复合材料中LDH含量的影响，确定了LDH比例与铬酸盐去除效率之间存在正相关关系。在不同浓度（等温线）和接触时间（动力学）条件下进行了LDH-BT_SP对铬酸盐的吸附实验。等温线实验结果与Langmuir和Freundlich等温线模型拟合良好，表明非均相LDH-BT_SP对铬酸盐的多层吸附，且LDH纳米颗粒分布均匀。在填充有硅砂的柱上研究了所制备的LDH-BT_SP的迁移率，结果表明与LDH杂化后膨润土的迁移率显著降低。此外，当将LDH-BT_SP注入填充有硅砂的箱式容器中以模拟地下土壤条件时，在170分钟内铬酸盐去除效率约为43%。因此，证实了通过固相杂化制备的LDH-BT是一种用于原位土壤和地下水修复的实用粘土基纳米复合材料。
