A 3D net-like structured fluorescent aerogel based on carboxy-methylated cellulose nanofibrils and carbon dots as a highly effective adsorbent and sensitive optical sensor of Cr (VI)

To effectively detect and remove Cr(VI) from aqueous solution, a 3D net-like structured fluorescent aerogel was designed and synthesized using highly photoluminescent carbon dots (CDs) and renewable natural carboxy-methylated cellulose nanofibrils (CM-CNFs). The surface morphology, microstructure, chemical elements and fluorescence properties of this novel aerogel were studied. Adsorption experiments were designed to investigate the adsorption of Cr(VI) onto this fluorescent aerogel. The adsorption process was described by the pseudo-second-order kinetic model and Freundlich model, and the maximum adsorption capacity for Cr(VI) reached 433.5 mg g(-1). Furthermore, this novel aerogel emitted bright blue fluorescence with a quantum yield of 11.8% when applied to Cr(VI) sensing, and a good linear relationship between the quantum yield and Cr(VI) concentration was demonstrated. Accordingly, this novel 3D net-like structured fluorescent aerogel should be a promising smart sorbent for the removal of Cr(VI) with advantages of the 3D net-like structure and rich functional groups that accelerate Cr(VI) adsorption and the wrapped fluorescent probe that improves Cr(VI) sensing.