Jiang Yunzhe, Liu Chuanyao, Huang Aisheng
Shanghai Key Laboratory of Green Chemistry and Chemical Processes, Department of Chemistry , East China Normal University , Dongchuan Road 500 , Shanghai 200241 , China.
ACS Appl Mater Interfaces. 2019 Sep 4;11(35):32186-32191. doi: 10.1021/acsami.9b11850. Epub 2019 Aug 22.
The removal of heavy-metal ions from wastewater has drawn intense attention, because of their toxicity, bioaccumulation tendency, and persistency in nature. Adsorption is regarded as one of the most promising methods, because of its simplicity and efficiency. In the present work, we report the preparation of a novel EDTA-functionalized covalent organic framework (COF) for the removal of heavy-metal ions. First, a COF named TpPa-NO was reduced to TpPa-NH by using NaSO as a reductant, and then EDTA dianhydride was grafted onto TpPa-NH to obtain TpPa-NH@EDTA through post-modification. Both the COF morphology and structure remained unchanged after post-modification. The TpPa-NH@EDTA showed excellent performance in adsorbing different types of heavy-metal ions, such as soft Lewis acid (Ag, Pd), hard Lewis acid (Fe, Cr), and borderline Lewis acid (Cu, Ni), and the removal efficiencies are all >85% within 5 min, because of the strong chelation effect of EDTA. The TpPa-NH@EDTA also showed high adsorption ability in a pH ≥3 environment and have an adsorption capacity of >50 mg/g for the six representative heavy-metal ions. This work provides a new idea for the application of COF materials in the removal of heavy-metal ions from wastewater.
由于重金属离子具有毒性、生物累积倾向以及在自然界中的持久性，从废水中去除重金属离子已引起了广泛关注。吸附因其简单高效而被视为最具前景的方法之一。在本工作中，我们报道了一种用于去除重金属离子的新型乙二胺四乙酸（EDTA）功能化共价有机框架（COF）的制备。首先，以亚硫酸钠为还原剂，将名为TpPa-NO的COF还原为TpPa-NH，然后通过后修饰将EDTA二酐接枝到TpPa-NH上，得到TpPa-NH@EDTA。后修饰后，COF的形态和结构均保持不变。TpPa-NH@EDTA在吸附不同类型的重金属离子方面表现出优异性能，如软路易斯酸（Ag、Pd）、硬路易斯酸（Fe、Cr）和边界路易斯酸（Cu、Ni），由于EDTA的强螯合作用，在5分钟内去除效率均>85%。TpPa-NH@EDTA在pH≥3的环境中也表现出高吸附能力，对六种代表性重金属离子的吸附容量>50 mg/g。这项工作为COF材料在去除废水中重金属离子的应用提供了新思路。
