Abstract
The fruit crop residues produce large volumes of agricultural lignocellulosic biomass, constituting a potential, homogeneous, concentrated and low-cost raw material. Among these, the European hazelnut (Corylus avellana) emerges as a potential source of biofuels and chemicals from its residues, of which the shell represents 42% of the total harvested biomass. In Chile, its production is relevant, and the species has adapted well, which has allowed its expansion in the country, occupying a total area in 2019 of 24,437 ha and a production of 35,000 tons/year of hazelnuts with shell. The objective of this study is to explore the feasibility of a combined extraction of polyphenols of interest with a subsequent conversion to bio-oil (biofuel) from hazelnut shells. The chemical composition of this residue was 20.1% of extractives, 49.7% of holocellulose, 37.8% alpha celullose, 30.2% of lignin and 0.7% of ash. This material presented 20.6% of fixed carbon, 68.7% of volatile and a lower 12% hemicellulose and calorific value of 4,431 Kcal/Kg. To extract tannins from ground hazelnut shells, the most effective method was to use Acetone 70% and stir for 60 minutes at 45°C. By increasing the time of extracting tannins only the biochar decreased its content. Bio-oil and pyrogenic acid showed no changes due to increased extraction time. Therefore, converting of hazelnut shells into useful chemicals, such as tannins before obtaining bio-oil, becomes a viable strategy to better exploit these residues.
