Extraction and Physicochemical Characterisation of Neem Seed Oil for Potential Use as a Biolubricant

The global shift toward bio-based lubricants has highlighted the potential of vegetable oils as environmentally benign alternatives to petroleum-derived lubricants. This study extracts and characterises neem seed oil for potential application as a biolubricant base stock, using seeds sourced from Bauchi State, North East Nigeria. Seeds were dried, dehulled, and solvent-extracted using n-hexane at 60 degrees Celsius in a Soxhlet extractor for 6 hours. The extracted oil was degummed, bleached, and deodorised, then comprehensively characterised for viscosity index, flash point, pour point, cloud point, kinematic viscosity at 40 and 100 degrees Celsius, acid value, saponification value, iodine value, specific gravity, refractive index, oxidative stability by Rancimat, and fatty acid composition by GC-MS. Kinematic viscosity at 40 degrees Celsius was 38.2 cSt and at 100 degrees Celsius was 8.1 cSt, with a viscosity index of 174, indicating superior temperature-viscosity performance relative to most mineral oils. Pour point of negative 6 degrees Celsius and flash point of 243 degrees Celsius indicate favourable low-temperature flow and fire safety properties for Nigerian operating environments. Fatty acid analysis revealed oleic (72.1%), palmitic (14.3%), and linoleic (9.8%) acids as dominant constituents. Oxidative stability of 14.2 hours by Rancimat at 110 degrees Celsius was adequate for a mono-grade bio-based lubricant base oil. Tribological testing is recommended as the next phase of evaluation. Keywords: neem seed oil, biolubricant, viscosity index, physicochemical properties, Bauchi State