A flame-retardant post-synthetically functionalized COF sponge as absorbent for spilled oil recovery

Frequent oil spills pose severe damages to the marine ecosystems and result in hazardous fires when the spilled oil is ignited. Developing high-performance, flame-retardant absorbent materials for large-scale water treatment is therefore urgently needed. Herein, we report an efficient post-synthetic silylation process to achieve a porous covalent-organic framework (COF), denoted as [CF3] − COF. The absorption capacity of oils and organic solvents in [CF3] − COF was explored by experimental measurements with the absorption mechanism illuminated by molecular simulations. The prepared [CF3] − COF powders were further loaded into melamine sponge to yield a highly hydrophobic absorbent denoted as [CF3] − COF@sponge, which was demonstrated to effectively remove oils/organic solvents with outstanding stability and excellent flame retardancy. Moreover, an oil-collecting apparatus was designed to continuously separate oils/organic solvents from water. The rapid recovery of oils/organic solvents from water using this device proves the great promise of [CF3] − COF@sponge in water treatment.