Click chemistry-induced modification of covalent organic framework/cellulose aerogels for removal of dye and heavy metal ions

In the context of sustainable development, the escalating need for hazardous wastewater treatment underscores the importance of developing innovative cellulose adsorbents for pollutant removal and separation. This study introduces a novel aerogel composed of a vinyl-functional covalent organic framework (COFs) and cellulose nanofibrils synthesized via in situ growth of COFs on aminated cellulose nanofibers (ACNFs). The aerogel’s surface is enriched with active functional groups (hydroxyl, amino, aldehyde, benzene, etc.), enabling diverse physical and chemical interactions with pollutants. Furthermore, a simple post-modification strategy involving thiol-ene click reactions was employed to modify the surface vinyl groups, resulting in two new aerogels (ACNF/COF-COOH and ACNF/COF-SH) to enhance interactions with different aqueous pollutants, specifically by targeting the removal of cationic dyes such as methylene blue (MB) and heavy metals. ACNF/COF-COOH aerogel exhibited a maximum adsorption capacity of 563.0 mg/g for MB, while ACNF/COF-SH aerogel demonstrated high selectivity for heavy metal ion removal, with a mercury ion (Hg²⁺) distribution coefficient (K_d) of 22,782.0 mL/g. This novel cellulose-based aerogel offers significant potential for removing pollutants from water bodies.