Waste valorization for sustainable advanced materials and catalysts

The process of waste valorization, which involves converting trash materials into valuable resources, is particularly relevant in today's world, given the pressing environmental and economic challenges. Current research focuses on the valorization of diverse waste streams: steel slags from metallurgical production, cigarette butts, and invasive tunicates from aquaculture for producing cellulose. Steel slags were utilized as support for copper and iron oxide catalysts, thanks to their alkaline features. The Cu/Steel Slags catalysts showed high activity in the reduction of nitroarenes in water in the presence of sodium borohydride as the reducing agent at room temperature. The FeOx/Steel Slags catalysts were employed in the catalytic transfer hydrogenation of nitrobenzene in the presence of isopropanol as the hydrogen source, without adding any external base, such as potassium or so-dium hydroxide. Concerning the valorization of cigarette butts, cellulose acetate was success-fully recovered from them using inexpensive and sustainable solvents, such as water, NaCl solution and ethanol. An optimized purification protocol was developed, yielding high-purity cellulose acetate suitable for reuse in polymer applications. Furthermore, in the framework of invasive tunicate valorization, an innovative and sustainable protocol for efficient extraction of cellulose from them was developed. The species under study, Clavelina oblonga, was subjected to acidic deep eu-tectic solvent (DES) treatment by using choline chloride and oxalic acid in 1:1 molar ratio under microwave irradiation obtaining purified cellulose having proprieties comparable to those observed by using conventional extractive procedures based on toxic and expensive reagents.