Additional valorization of waste biomass: exhausted lemon peels, coffee silverskins and paper wastes for the production of levulinic acid

In recent years, the interest of industry has deeply increased towards the exploitation of any kind of waste biomass for the synthesis of new valuable biofuels and bioproducts, in place of the dwindling traditional fossil ones. In this context, the acid-catalysed hydrothermal route for the synthesis of levulinic acid may represent a smart approach for the sustainable exploitation of waste biomasses. In this context, wastes deriving from i) the “Limoncello” liqueur production, ii) coffee roasting thermal treatment, and iii) converting operations to produce tissue paper, were adopted in order to produce levulinic acid, adopting water as a reaction solvent and very dilute hydrochloric acid as a homogeneous catalyst for the hydrolysis/dehydration of the cellulose fraction. The optimization of the hydrolysis reaction of this waste has allowed us to obtain interesting levulinic acid yield under the best reaction conditions. The described examples evidence an integrated valorisation of the starting biomass, in agreement with the Biorefinery concept and the environmental sustainability, nowadays oriented towards the “Zero waste” policy.