A Review on Bio-Lubricants as an Alternative Green Product: Tribological Performance, Mechanism, Challenges and Future Opportunities

Industries, especially those related to transportation, have relied extensively on petroleum products for lubrication, raising serious questions about the security of the world energy supply in the future. Observed that the end-products might be released back into the environment, posing major environmental risks. As a result, bio-based products have attracted increasing interest as prospective replacement to mineral-based type due to their important role in resolving the issues of pollution. With renewability and biodegradability as their greatest points, bio-based lubricants have been discovered to offer superior lubricating qualities to those of traditional mineral lubricants but currently have some undesirable qualities that need to be improved based on the literatures. Therefore, this research objective is to showcase the potential of bio-lubricants, both in terms of their environmental benefits and for technical applications, based on studies that have been published over the years. Review of the natural oil's molecular structures, physio-chemical characteristics, and lubricating ability is crucial for the creation and choice of lubricants. Owing to their accessibility in a wide range of characteristics, which are necessary for specific applications, bio-based lubricant is a possible replacement for a variety of applications, according to the primary findings. The results showed that sunflower oil improved in reducing friction and wear by 93.7% and 70.1%; and 77.7% and 74.1%, under TiO2 and SiO2 studied, against base lubricant values of 0.0511 and 11.2414 (mm3), respectively. However, to get beyond some of the restrictions such as poor low temperature and oxidative stability, adequate chemical modification is necessary in solving agglomeration challenges.