Levulinic acid production from the green macroalgae Chaetomorpha linum and Valonia aegagropila harvested in the Orbetello lagoon

Eutrophication of coastal areas is a global environmental problem. This phenomenon can cause massive blooms of opportunistic macroalgae and drastic reduction of dissolved oxygen levels due biomass decomposition with consequent impact on aquatic ecosystems. This is true for example for the Orbetello lagoon (Italy, Southern Tuscany) that covers a surface of about 25 km2 and is characterized by low water turnover. To attempt to solve eutrophication problems, a large amount of algal biomass is removed every year from the lagoon (about 700/1000 t/year) but this practice is highly expensive and creates a disposal problem. Various efforts have been made to employ the harvested biomass, but up to date a viable industrial application has not been found. In this context now, for the first time, we have studied the direct conversion of two different macroalgae, harvested in the Orbetello lagoon, Chaetomorpha linum (Muller) Kutzing and Valonia aegagropila C.Agardh, to produce levulinic acid, adopting the one-pot hydrothermal treatment in the presence of aqueous diluted mineral acids. The acid-catalyzed conversion of these algal biomasses to levulinic acid was optimized studying the effect of the main reaction parameters. Based on this preliminary study, levulinic acid yields of 19 g LA/100 g DB for C. linum and 16 g LA/100 g DB for V. aegagropila were reached. These results confirm the significant potential of these waste green algae as a renewable starting feedstock for platform chemicals production.