Ultralight and shapeable nanocellulose/metal-organic framework aerogel with hierarchical cellular architecture for highly efficient adsorption of Cu(II) ions

Water contamination by heavy metal pollutants is a global concern due to detrimental effects on the environment and human health. Regenerable, high-performance heavy metal sorbents are urgently demanded for improved water purification. Herein, we present an elegant strategy of interweaving metal-organic framework (MOF-808-ethylene diamine tetraacetic acid) and TEMPO-oxidized cellulose nanofibers (TCNF) to construct freeways in hybrid aerogels for rapid and efficient transport and capture of heavy metal ions. In this strategy, a postsynthetic ligand exchange approach is applied to introduce ordered and high-density accessible binding sites for metal ions. The prepared aerogels show excellent shapeability, ultralow density less than 0.005 g cm-3, and high hierarchical porosity of 99.82%. Furthermore, benefiting from the abundant chelating groups and accessible surface areas, these aerogels exhibit outstanding uptake capacity of 300 mg g-1 and rapid adsorption kinetics of 0.031 mg g-1 h-1 for Cu(II) ions, significantly better than conventional TCNF aerogels. The aerogels could be easily regenerated at least five cycles without greatly performance loss. These aerogels could effectively remove diverse heavy metal ions from complicated contaminated water. Thus, this work provides a novel method to synthesize environmental-friendly, regenerable, and high-performance adsorption materials for water remediation.