The growing demand for environmentally benign lubricants has intensified research into bio-based alternatives derived from non-edible and underutilized oil resources. In this study, oils extracted from Strychnos spinosa (monkey orange), Jatropha curcas, and Lagenaria sphaerica (wild calabash) sourced from Taraba State, Nigeria, were investigated as potential feedstocks for high-performance bio-lubricant production. Crude oils were obtained via Soxhlet extraction, characterized for physicochemical properties, and subsequently subjected to acid-catalyzed esterification followed by base-catalyzed transesterification to produce lubricant-grade ester base stocks. The modified oils were formulated into neat bio-lubricants and further enhanced with zinc oxide (ZnO) nanoparticles to obtain nano-lubricant formulations. Chemical modification markedly reduced acid values to below 1 mg KOH g⁻¹ and improved kinematic viscosity and viscosity index, indicating enhanced rheological stability. Tribological evaluation revealed significant reductions in coefficient of friction and wear scar diameter upon ZnO incorporation, accompanied by substantial improvements in extreme-pressure performance. Thermal analysis (TGA/DSC) demonstrated increased onset degradation temperatures and higher residual mass for ZnO-enhanced formulations, confirming improved thermal stability. Among the investigated feedstocks, wild calabash and monkey orange oils exhibited superior responses to nano-enhancement. Overall, the results demonstrate that chemically modified, ZnO-reinforced bio-lubricants derived from underutilized non-edible seed oils can achieve tribological and thermal performance comparable to conventional synthetic lubricants, offering a sustainable and environmentally friendly alternative for industrial lubrication applications.
Ezekiel Emmanuel (Fri,) studied this question.