Moving forward into a second golden age: Innovative and sustainable production of reprocessed starch aerogels.

Bioaerogels are nanostructured materials with potential applications from biomedicine to environmental sciences. Their production at large scale needs to cause minimal environmental impact. Thus, designing strategies for a successful end-of-life handling is essential. Reprocessing and recycling are favorable alternatives to disposal, allowing the material to remain in use by maintaining its original properties. This work studies the reprocessing of polysaccharide aerogels into new aerogels for the first time. Three different reprocessing methods for starch aerogels are proposed, all of which avoid the use of energy-intensive techniques and hazardous reagents. These methods employ sustainable approaches (grinding, redissolving, ambient, and oven drying), and use mild, safe reagents like water and ethanol. The original and reprocessed aerogels were obtained in all cases by supercritical CO2 drying. They were then characterized and compared with each other in terms of physicochemical properties (composition, texture, crystallinity, thermal and mechanical stability). The prepared aerogels, regardless of the followed reprocessing strategy, were very similar to the original. This paves the way for their application in different production scenarios following circular economy principles.