Selective extraction of natural products with benign solvents and recovery by organophilic pervaporation: Fractionation of D-limonene from orange peels

There has been a growing awareness of the need to replace volatile organic compounds (VOCs) by benign solvents aiming to implement more sustainable processes. Accordingly, this work aims at evaluating a new and more friendly process based on the use of benign solvents with different hydrophobicities, namely common alimentary oil, polypropylene glycol and polyethylene glycol, for the selective recovery of natural products, followed by pervaporation. Particularly, the extraction and fractionation of limonene from orange peels was studied and optimised, where a high value product is obtained from a highly abundant material that is mostly disposed. Firstly, the best benign solvents were selected, in order to obtain high yields of extraction, and then pervaporation and vacuum distillation were compared after the extraction process, in order to obtain high yields of global recovery of limonene with the least contaminants possible. The integrated process selected was the extraction of limonene from orange peels using polypropylene glycol 240 (PPG), followed by organophilic pervaporation, providing the selective recovery of limonene free of solvent.