Metal-based oxoanions are potentially toxic pollutants causing serious water pollution. Therefore, the segregation of such species has recently received significant research attention. Even though several excellent adsorbents have been employed for the effective management of chemicals, their limited microporous nature along with non-monolithic applicability with relatively slow kinetics and less selectivity thwarted their large-scale real-time application. Herein, we strategized a unique anion exchangeable hybrid composite aerogel material (IPcomp-6), integrating a stable cationic metal-organic polyhedron with a hierarchically porous metal-organic gel, encoded with selective oxoanions trapping moieties. The composite scavenger demonstrated a highly selective and very fast segregation efficiency for various hazardous oxoanions such as, HAsO₄²⁻, SeO₄²⁻, ReO₄⁻, CrO₄²⁻, and MnO₄⁻ in water in the presence of ~100-fold excess of other coexisting anions. The material was able to selectively eliminate trace HAsO₄²⁻ even at low-concentration to well below the As(V) limit in drinking water defined by the WHO in presence of other anions. Moreover, the hybrid material can successfully eliminate arsenate from natural drinking water samples and simulated industrial wastewater samples, in both batch and dynamic column exchange sorption experiment. The mechanistic role of multifunctionalities of IPcomp-6 towards efficient arsenate capture was further investigated by numerical flow-velocity experiments along with theoretical calculations.

A hybrid composite aerogel material has been systematically fabricated by encapsulating an active nanosized cationic metal-organic polyhedra in a stable hierarchical porous metal-organic gel matrix. The hybrid aerogel demonstrated efficient and highly selective extraction of metal-based toxic oxoanions in both batch and dynamic column exchange experiment form simulated industrial waste-water and natural ground water system.

Dr. Sahel Fajal

Indian Institute of Science Education and Research, Pune

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