Sustainable production of bio-based lubricants from agricultural waste: A review

The rising environmental problems related to oil-based lubricants, which include toxicity, non-biodegradability, and shortage of oil resources, have cause researchers into search for alternative sources of sustainable lubricants. The potential of agricultural waste products for developing sustainable bio-lubricants is therefore considered in this review. Different forms of agricultural waste such as, animal fat, waste cooking oil, nonedible oils etc. are considered for their use as raw material in the production of bio-based lubricants and compared with conventional biolubricants. Different types of reactions, like epoxidation, estolide formation, transesterification, and hydrogenation are reviewed. A discussion on characterization parameters is provided to evaluate the bio-efficiency of the lubricants related to viscosity/viscosity index, thermogravimetric analysis and role of nanoparticles as additives. In addition, ecofriendly biolubricants also reviewed and compared with those of mineral oils, synthetic oil lubricants and plant oil lubricants. Although many progresses have been achieved in this field, there are still many challenges in scale up and commercialization of bio lubricants due to their high production cost, supply chain issues, shelf life and storage.