Extraction and purification of d-limonene from orange peel wastes: Recent advances

Orange peel wastes, with an estimated global annual production of 25 million tonnes, are problematic to dispose of but can be used to obtain a range of valuable products, among them the main constituent of orange essential oil, D-limonene (DL). This review aims to layout recent advances in the field of DL extraction and purification. Besides substitution of the conventional solvent hexane with certain bio-based solvents, a range of techniques are presented. These include enhanced solvent extraction processes through temperature and pressure intensification or ultrasound, improved distillation most commonly using different microwave-based techniques but also enzymes, and supercritical CO2 extraction. Even though purification has been found to be the most energy-intensive and environmentally impacting step, most studies did not improve on existing centrifugation, decantation, or fractional distillation methods. Chromatography has been proven effective at obtaining high DL purities; however, it still has to be improved because of its high costs and low productivity.

Automated summary

This review presents recent advancements in the extraction and purification of D-limonene (DL), the main constituent of orange essential oil, from orange peel waste. Various techniques, such as the use of bio-based solvents, enhanced solvent extraction processes, improved distillation methods, and supercritical CO2 extraction, are discussed.