High-Adsorption, Self-Extinguishing, Thermal, and\nAcoustic-Resistance Aerogels Based on Organic and Inorganic Waste\nValorization from Cellulose Nanocrystals and Red Mud

Waste\ntransformation as the source to valuable materials is an\neffective strategy for the high-valued valorization in view of socioeconomic\nand environmental issues. Inspired from the concept of organic–inorganic\nhybrid, we proposed the utilization of cellulose nanocrystals (CNCs,\nextracted from biomass waste) and red mud (RM, from industrial waste)\nto fabricate composite aerogels as potential construction materials\nwith the multifunction of adsorption, thermal insulation, acoustic\nresistance, and flame retardancy. For equal loading level of modified\nCNC (Si-CNC) and RM (1:1, w/w) components, the obtained aerogel was\nchemically cross-linked with diisocyanate to enhance its structural\nstability and mechanical properties. It exhibited an improved compression\nmodulus of 3.7 MPa together with high porosity (98.8%) and specific\nsurface area (73.23 m2/g). As a result of the intrinsic\nfeatures of organic Si-CNC (skeleton) and inorganic RM (particles\naggregate), the Si-CNC/RM-1/c composite aerogel displayed significant\nfunctional performances such as magnetic conductivity, rapid oil adsorption\nof 30 times its mass, 20.8% reduction in thermal conductivity, 24.5%\nincrease in sound-absorption coefficient, and highly efficient self-extinguishing\nbehavior within 2 s.