Potentials of Citrus Peel Waste Valorisation for Green Diesel Production: A Mini Review

Abstract

The utilisation of fossil derived diesel for running diesel-based transportation has caused anthropogenic Green House Gas (GHG) emission. Environmental challenges seen in the form of acid rain and global warming are attributed to the high release of these emissions. Consequent upon these impacts, the application of renewable fuel for diesel engine operation is a good option to aid reducing GHG emissions. Citrus peel, a biomass waste produced after extracting the most valuable fruit juice, contains oil with fuel-like properties that can be explored as biofuel. The presence of limonene in citrus peel acting as a microbial growth inhibitor, limits the decomposition of citrus peel waste which causes generation of bad odour over a long period with tendency for aiding disease outbreak. Citrus peel waste valorisation for green diesel production presents a double fold benefit. It contributes in effective waste management of citrus peel biomass waste and provides environment friendly green sustainable energy source in support of the United Nations Sustainable Development Goals number 7 and 13. This study aims to present a mini review on the potentials of citrus peel waste valorisation methods for green diesel production. Supercritical Fluid Extraction Method was found to be the method with potential for optimum CPO yield for green diesel production. Some fuel properties of CPO relative to diesel varies with wide margin, a challenge to be remedied by hydrotreatment for the CPO to behave similar to conventional diesel. The catalytic hydrotreatment may be the new direction towards a cleaner and greener renewable diesel synthesis.