Functionalized covalent organic framework aerogels for highly efficient removal of anionic and cationic dyes

Covalent organic frameworks (COFs) have attracted extensive attention as promising materials for the elimination of various organic pollutants due to their high surface area, inherent porosity and tailorable functionality. However, powdery COFs are difficult to separate and reuse, which greatly limits their practical applications. Herein, a beta-cyclodextrin functionalized imine COF (beta-CD-COF) aerogel with good crystallinity and chemical stability was synthesized by the Schiff base reaction using a one-pot method for efficient removal of anionic and cationic dyes from water. The prepared beta-CD-COF aerogel has a macroscopic three-dimensional bulk and hierarchical porous structure, which is conducive to adsorption and recovery, and it not only showed high adsorption capacity and fast binding kinetics for single anionic and cationic dyes (3403.91 mg g-1 for methyl orange (MO) and 2199.37 mg g-1 for methylene blue (MB)), but also exhibited outstanding simultaneous adsorption capacity in different binary and ternary pollutant systems. Additionally, the beta-CD-COF aerogel showed good reusability for the co-adsorption of MO and MB. These results demonstrate the great potential of beta-CD-COF aerogels for the simultaneous removal of anionic and cationic dyes in environmental applications. A beta-CD-COF aerogel, with good crystallinity and chemical stability, exhibits high adsorption capacity, fast binding kinetics for single anionic and cationic dyes and outstanding simultaneous adsorption capacity in multi-pollutant systems.