Methodologies to Re-Refine Used Lubricant Oils

Lubricant oils, essential for minimising friction between moving parts, find application across diverse industries such as automotive, industrial, marine, aviation, and energy production. The automotive sector primarily drives lubricant oil consumption, while the industrial domain follows suit. The global lubricants market, valued at USD 128.51 billion in 2020, demonstrates a growing trend, emphasising the escalating significance of lubricant oils. Traditionally derived from crude oil, the depletion of this source raises concerns. Moreover, disposal practices involving incineration and landfill contribute to environmental issues. Consequently, the pursuit of environmentally sustainable methods for disposal and reuse has become critical. "Re-refining" emerges as a rising technique, involving the removal of contaminants from used lubricant oils to restore their utility. This approach is not only eco-friendly but also conserves resources by reducing the need for fresh oil production. Moreover, re-refined lubricant oils often surpass industry standards, driven by advanced refining technologies. However, this method also produces potentially hazardous by-products, necessitating regulatory scrutiny. The study undertakes a comprehensive analysis of available methods, primarily focusing on engine oil, to determine an environmentally viable and economically feasible approach to re-refine used lubricant oils. The research presents a methodological exploration of re-refining used lubricant oils, driven by the urgency of sustainable development. The vacuum distillation-based approach, involving sequential operations of Dehydration, Vacuum Distillation, and Lube Oil Distillation and Condensation, emerges as a promising solution. This approach effectively removes water and contaminants, precisely fractionates components, and employs MEK (Methyl Ethyl Ketone) to enhance lubricating oil quality. The advantages include resource efficiency, waste minimisation, and high-quality re-refined products. While re-refining mitigates environmental concerns, certain challenges, including by-product hazards, necessitate careful consideration. This review underscores the need for and viability of re-refining as a path toward sustainable development, addressing environmental concerns while fostering economic growth in the lubricant industry.