Highly Efficient and Robust Monolith of a Metal–Organic Framework Hybrid Aerogel for the Removal of Antimony from Water

Abstract

Antimony contamination is of increasing concern across various environmental media. Removal of antimony from water is a pressing issue, and an associated challenge in the operational treatment of wastewater is developing material of high Sb absorbance efficiency together with facile applicability. This work details, for the first time, a 3D porous hybrid aerogel comprising metal–organic frameworks (MOFs) embedded in the cellulose nanocrystal matrix using a bottom-up approach based on hydrazone cross-linking of hydrazide and aldehyde, specifically designed for removal of Sb(V) from contaminated water. The hybrid aerogel was fabricated, and the resulting product presents a monolithic architecture with a diameter of 2 cm and a super low density of 7.96 mg cm–3. The hybrid aerogel has fast adsorption kinetics, a broad working pH range, strong anti-interference capability, and high selectivity. In particular, the material has an ultrahigh adsorption capacity (575 mg g–1) for Sb(V) that is far superior to other adsorbents. Site energy thermodynamic and mass transfer modeling results demonstrated that the cross-linked celluloses greatly disperse and protect the embedded MOFs so that abundant active Bi–O sites strongly adsorb Sb(V) by forming Bi–O–Sb bonds. Almost complete (97%) removal of Sb(V) from 5 mL of spiked tap water (50 μg L–1) was achieved in 2 min by simple extrusion through a syringe device assembled with blocks of the hybrid aerogel and is well below the maximum contaminant level for Sb(V) of 6 μg L–1 in drinking water. This work paves the way for shaping powder adsorbents into convenient and tailorable free-standing monoliths, and with these features the hybrid aerogel is a promising candidate for practical treatment of Sb(V)-contaminated water.