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.