Nanotrap Grafted Anion Exchangeable Hybrid Materials for Efficient Removal of Toxic Oxoanions from Water

Water pollution has attracted worldwide significant attention ever since the finding of its harmful effects on the whole ecosystem, including human health. Although several materials are known for selective removal of specific contaminants, designing a single material that can adsorb a variety of water contaminants is still a very challenging task due to a lack of proper design strategies. Herein, we have rationally designed a new class of anion exchangeable hybrid material where the nanosized cationic metal–organic polyhedra (MOP) are embedded inside a porous covalent organic framework (COF) with specific binding sites for toxic oxoanions. The resulting hybrid material exhibits very fast and selective sequestration of high as well as trace amount of a wide range of toxic oxoanions (HAsO42–, SeO42–, CrO42–, ReO4–, and MnO4–) from the mixture of excessive (∼1000-fold) other interfering anions to well below the permissible drinking water limit. Moreover, the hybrid cationic nanotrap material can reduce the As­(V) level from a highly contaminated groundwater sample to below the WHO permitted level.

水污染因其对包括人类健康在内的整个生态系统的有害影响，自被发现以来便受到全球范围内的广泛关注。尽管已有多种材料可实现特定污染物的选择性去除，但由于缺乏合适的设计策略，开发能够吸附多种水污染物的单一材料仍是一项极具挑战性的任务。在此，我们合理设计了一类新型阴离子可交换杂化材料：将纳米级阳离子金属有机多面体（metal–organic polyhedra，MOP）嵌入具备有毒含氧阴离子特异性结合位点的多孔共价有机框架（covalent organic framework，COF）中。所得杂化材料可在含过量（约1000倍量）其他干扰阴离子的混合体系中，快速且选择性地捕集大量乃至痕量的多种有毒含氧阴离子（HAsO42–、SeO42–、CrO42–、ReO4–及MnO4–），使其浓度远低于饮用水允许限值。此外，该阳离子纳米陷阱杂化材料可将高污染地下水样品中的As(V)浓度降至世界卫生组织（World Health Organization，WHO）规定的允许限值以下。