State Key Laboratory of Pollution Control and Resource Reuse/School of the Environment, Nanjing University, Jiangsu, 210046, China.
State Key Laboratory of Pollution Control and Resource Reuse/School of the Environment, Nanjing University, Jiangsu, 210046, China.
Chemosphere. 2022 Nov;306:135503. doi: 10.1016/j.chemosphere.2022.135503. Epub 2022 Jun 28.
Nanoscale zero-valent iron (nZVI) has drawn great interest in the remediation of contaminated waters. In this study, we prepared a novel and stable nZVI embedded in N-doped carbon matrix (nZVI@MOF-CN) using a facile direct carbonization method, in which an iron-containing metal-organic framework (MOF) served as both the iron and carbon sources, and melamine as the nitrogen source. The nZVI@MOF-CN composites were used in the removal of bromate in water, which could be effectively reduced by the surface electrons transferred from nZVI to the carbon encapsulation layer due to the Schottky-Mott effect. Doped nitrogen significantly facilitated the reduction of bromate by nZVI, because it enhanced the nZVI dispersion and bromate adsorption, and modulated the carbon matrix conductivity. The bromate reduction activity of nZVI@MOF-CN was more than 50 times higher that of its un-doped counterpart and a commercial nZVI. Moreover, owing to the protection of carbon encapsulation layer, nZVI@MOF-CN exhibited good stability and reusability. The leached concentration of iron ions of nZVI@MOF-CN was less than 5% of the commercial nZVI under the same reaction conditions. Commercial nZVI almost completely lost its bromate reduction activity after use (3% reduction efficiency in the examined time frame), while nZVI@MOF-CN maintained a reduction efficiency of 61%. The nZVI@MOF-CN could be effectively regenerated by hydrogenation reduction. After five reaction-regeneration cycles, nZVI@MOF-CN still achieved a bromate reduction efficiency of approximately 80%. These results suggest that MOF-derived nZVI materials are highly reactive and stable for the reductive removal of pollutants in water.
纳米零价铁（nZVI）在受污染水的修复中引起了极大的关注。在这项研究中，我们使用简便的直接碳化法制备了一种新型稳定的嵌入氮掺杂碳基质中的 nZVI（nZVI@MOF-CN），其中含铁的金属有机骨架（MOF）既是铁源又是碳源，三聚氰胺作为氮源。nZVI@MOF-CN 复合材料用于水中溴酸盐的去除，由于肖特基-莫特效应，nZVI 表面电子转移到碳包封层，可有效还原溴酸盐。掺杂氮显著促进了 nZVI 对溴酸盐的还原，因为它增强了 nZVI 的分散性和溴酸盐的吸附，并调节了碳基质的导电性。nZVI@MOF-CN 的溴酸盐还原活性比其未掺杂的对应物和商业 nZVI 高 50 多倍。此外，由于碳包封层的保护，nZVI@MOF-CN 表现出良好的稳定性和可重复使用性。在相同的反应条件下，nZVI@MOF-CN 的铁离子浸出浓度低于商业 nZVI 的 5%。商业 nZVI 在使用后几乎完全失去了其溴酸盐还原活性（在考察时间范围内还原效率为 3%），而 nZVI@MOF-CN 保持了 61%的还原效率。nZVI@MOF-CN 可以通过氢化还原有效再生。经过五次反应-再生循环后，nZVI@MOF-CN 仍可实现约 80%的溴酸盐还原效率。这些结果表明，MOF 衍生的 nZVI 材料对水中污染物的还原去除具有高反应性和稳定性。
