Evaluation of the Physico-Chemical Properties of Locally Sourced Cashew Nut Oil (CNO) and Shea Butter Nut Oil (SBNO) for Lubricant Applications

Abstract

The global lubricant industry is increasingly seeking sustainable and environmentally friendly alternatives to petroleum-based oils. This study investigated the potential of two underutilized, edible vegetable oils Cashew Nut Oil (CNO) and Shea Butter Nut Oil (SBNO)as viable base stocks for bio-lubricants. Oils were extracted from locally sourced cashew and shea nuts using a Soxhlet apparatus with n-hexane as the solvent. A comprehensive analysis of key physico-chemical properties relevant to lubricant performance was conducted following standardized ASTM and AOAC methods. The physical properties evaluated included kinematic viscosity at 40°C and 100°C, viscosity index (VI), pour point, flash point, specific gravity, and moisture content. Chemical properties assessed were acid value, saponification value, iodine value, peroxide value, and oxidation stability. The results revealed a distinct trade-off between the two oils. SBNO exhibited higher kinematic viscosity and superior oxidative stability (Induction Period: 18.5 hrs), making it suitable for high-load applications like greases. However, its high pour point (5°C) limits its low-temperature use. In contrast, CNO demonstrated a higher VI (185) and a significantly lower pour point (-6°C), indicating better performance across a wide temperature range, but it showed poor oxidative stability (Induction Period: 8.5hrs). The study concludes that while SBNO is an excellent product for stable, heavy-duty lubricants, CNO's superior thermophysical properties make it suitable for hydraulic and engine oils, provided its oxidative instability is mitigated. Both oils present promising, eco-friendly alternatives for specific lubricant applications