From agro-industrial lignocellulosic wastes to new generation biodiesel: an innovative biorefinery scheme based on the Green Chemistry and the Circular Economy

An innovative biorefinery model was designed and optimised for the multi-step conversion of each fraction of two lignocellulosic biomasses to give several high added-value bioproducts, such as sugars, organic acids, aromatics, triglycerides (single cell oil) and, above all, new generation biodiesel. The promising energy crop giant reed and the waste tissue paper collected from different paper companies in Tuscany (Italy) were adopted as substrates. Their hemicellulose and cellulose fractions were selectively depolymerised into xylose and glucose by different chemical and biological catalytic approaches adopting the principles of the Green Chemistry. Then, sugars were fermented into microbial oil by the oleaginous yeast Lipomyces starkeyi. This bio-oil was transformed into new generation biodiesel which represents an outstanding alternative to fossil fuels and traditional biodiesel. As an alternative, the cellulosic fraction of giant reed was converted into levulinic acid which represents one of the twelve “Top Value-Added Chemicals from Biomass”. Finally, the electrochemical oxidative depolymerisation of the remained lignin fraction into aromatics, such as vanillin, was studied at room temperature and atmospheric pressure by using Pt, NiOOH and graphite as electrodes and water as solvent.