Towards Sustainable Lubricants: A Biodegradability, Emissions and Wear Analysis of Cottonseed Oil-AMAs Blends for IC Engine Usage

Abstract

Aim: This research investigates cottonseed oil as a renewable lubricant for internal combustion engines, highlighting its high biodegradable properties, favourable emission profile, and wear-reduction potential compared to conventional mineral oils. Study Design, Place and Duration of Study: The experiment, conducted in Nigeria at Abubakar Tafawa Balewa University, Federal Polytechnic Bauchi, and Nenis Automobile Engineering Workshop, Lagos, involved both experimental analysis and engine performance testing on a JF 168 gasoline engine test-bed with an A.C. dynamometer. Methodology: Three key methods were employed: viscometric analysis of oil samples, and environmental breakdown was assessed over nine days by monitoring Pseudomonas aeruginosa growth on agar plates modified with oxidized cottonseed oil - aftermarket additives (AMAs) blended samples; exhaust emissions (CO₂, O₂, and CO) were analysed from a spark ignition engine using Orsat gas absorption; and aluminium wear debris was quantified via Flame Atomic Absorption Spectroscopy (FAAS) at a wavelength of 309.3 nm. Results: The study revealed that AMA is more viscous and less dense than cottonseed oil. Blends show viscosity decrease with temperature and higher cottonseed oil content, and the formulations demonstrated strong biodegradability, with microbial counts increasing from 1.19×105 cfu/ml (control) to 2.0×105 cfu/ml, and biodegradation rates rising from 0.0261 h−1 to 0.0276 h−1. CO2​ exhaust gases increased with the mixtures (e.g., B100–B40), indicating more complete combustion, while CO combustion by products spiked at mixtures like B50 and B65, reflecting partial inefficiencies. Unused O2 levels dropped at 3000 rpm, suggesting enhanced oxygen utilization. Aluminium wear debris analysis showed that multigrade oil had the lowest concentration, followed by cottonseed oil blends, with monograde oil yielding the highest concentration—highlighting better wear protection. Conclusion: The findings support cottonseed oil blends as eco-friendly lubricants with moderate emission and wear performance. This aligns with SDGs 7, 9, and 13, affirming the scientific potential and ongoing efforts to formulate bio-based lubricants through the strategic combination of various additives.