Pyrolysis of spent rapeseed meal: A circular economy example for waste valorization

This study describes an original procedure for protein extraction from rapeseed meal, which due to its well-balanced amino acid composition is used in livestock and aquaculture industries. The waste collected after the extraction process was converted through induction pyrolysis using two different set-ups and different reaction conditions. The choice of process parameters address the reaction towards a high formation of bio-oil (30.5%) and gas (30.7%) or the production of large quantities of bio-char (up to 53%). Bio-oils were characterized through GC–MS and 1H NMR, to evaluate its composition. The bio-oils are rich in nitrogenous aromatic compounds, in particular pyrrole and derivatives of pyrazines. In addition, other high value-added products such as furfuryl alcohol are also present. A TGA analysis was used to determine the thermal stability of the char and FT-IR analysis of the solid fraction shows the presence of residual functional groups on the surface. This study reveals that pyrolysis is a valid way for biomass conversion