Recovery of D-limonene through moderate temperature extraction and pyrolytic products from orange peels

D-limonene, a high-value added molecule found in the flavedo of orange peels (about 0.7% w/w), is used in the nutritional, pharmaceutical and cosmetic fields. An accelerated moderate temperature extraction was investigated in order to recover D-limonene. Furthermore, the residue from the extraction was used for energy recovery through the pyrolysis process. RESULTS: The proposed extractive process was able to recover D-limonene up to 0.48±0.002% w/w (on a wet basis) from orange peels at the highest investigated temperature (130°C for 60min). The residual matrix was then subjected to a dehydration step, which was carried out at room temperature for 10 days, in order to decrease the moisture from the porous surface, and then to a pyrolysis process. The average chemical energy recovery efficiency (91%±0.04) suggested that the thermochemical process is suitable for biofuel production. CONCLUSION: Orange peels can be exploited for the recovery of an important bio-product and the residue can be used as feedstock for biofuels. This work has confirmed that accelerated extraction is more efficient than Soxhlet extraction (more than 68% w/w against 37% w/w of total D-limonene, respectively), and that a pyrolysis process can be successfully performed on the residue