Evaluation of date seed (Phoenix dactylifera L.) oil as crop base stock for environment friendly industrial lubricants

Growing environmental concern and rapid consumption of poor biodegradable mineral oils have triggered the need for the development of eco-friendly biodegradable bio-based oils with low toxicity and excellent lubricating performance. The study aims to produce and evaluate the performance of date seed (Phoenix dactylifera L.) oil, which is abundantly available in the Middle East region, as an alternative bio-based lubricant. The optimum date seed oil (DSO) yield of 6% was achieved using solvent extraction of date seeds with particle size of 1 mm, hexane solvent to seed ratio of 6:1, and processing time of 18 hours. The physicochemical properties of the DSO were found such as its clear yellow color, density of 0.907 g/cm3, iodine value of 13.28 gl2/100 g, saponification value of 162.5 mg KOH/g, and acid value of 1.4 mg KOH/g. Moreover, fatty acid composition was analyzed employing quantitative gas chromatography (GC), and the oleic acid (41.1%), linoleic acid (21.4%), and palmitic acid (11.3%) were found to be the major unsaturated fatty acids. The pour and flash points were around  -10 °C and 140 °C, respectively. Thermogravimetric analysis (TGA) revealed that the produced DSO is thermally stable at up to 300 °C. The rheological properties such as viscosity (41.62 cSt at 40 °C and 8.13 cSt at 100 °C) and viscosity index 173 were also assessed. These properties along with tribological properties of the DSO were compared with other bio-based oils and commercial SAE20W40 mineral oil. Overall, the characteristics of the DSO showed good potential to be developed into a bio-based lubricant. Furthermore, its properties can be enhanced by adding suitable additives. The findings of this study will help in developing eco-friendly bio-based industrial lubricants.