Waste Biomass Valorisation for the Development of Sustainable Cellulosic Aerogels and their Sound Absorption Properties

Novel and more sustainable sound absorbing materials are produced through the valorization of waste biomass sources by following circular economy principles. Cellulosic nanocrystals (CNC) were extracted from Posidonia oceanica dead leaves, spent barely grains, kale stems (KS) using a simplified purification protocol. These used to prepare cellulosic aerogels, evaluating effect three parameters, namely, concentration (0.5–4%), CaCl2 poly(lactic acid) (PLA) incorporation (hybrid aerogels), on their absorption properties. Aerogels 4% suspensions show highest absorption, outperforming benchmark rockwool polyester—two modern commonly-used absorbers. Moreover, PLA coating also improves performance most aerogels. CNC KS aerogels selected as optimum at both high (500–6000 Hz) low (100–1500 frequency ranges. Overall, these results represent new proof-of-concept conversion high-performance that have excellent