Formulation and Performance Evaluation of Sustainable Bio-hydraulic Fluid from Spent Palm Kernel Oil Glycerin and Anacardium occidentale Leaf Extract as a Corrosion Inhibitor

This study explores a novel method for producing sustainable bio-hydraulic fluid by utilizing and optimizing the glycerin from spent palm kernel oil (PKO) using a bio-based corrosion inhibitor from Anacardium occidentale leaves (AO). PKO was utilized to mitigate its inadequate disposal and was treated by filtration and an esterification process. The saponification value of 193.22 mg/g of the PKO decreased to 174.87 mg/g after treatment. The glycerin obtained was characterized using a gas chromatography-mass spectrophotometer (GC-MS) and Response Surface Methodology (RSM) was employed to optimize the glycerin yield. FT-IR and phytochemical analysis of the AO leaf identified relevant functional groups, rich in alkaloids (212.45 ± 0.02 mg/100 g) and a high number of tannins (98.44 ± 0.14 mg/100 g), which demonstrate suitable corrosion inhibition characteristics. Functional groups of glycerin include polar atoms, and single and double-bond structures, which indicate lubricity hence the glycerin is suitable for bio-hydraulic fluid formulation. The optimum glycerin yield was obtained at 89.95% with an oil/methanol ratio of 6.10, time of 71.17 min, temperature of 91.30 °C, and catalyst dosage 1.06. The percentage deviation was below 0.2%. As a result, The suggested Model is significant. The bio-hydraulic fluid's functional groups include heteroatoms and double and triple bonds typical for bio-hydraulic fluid, these demonstrate suitability for hydraulic applications. Its pour point is -43.9°C, its flash point is 253°C, its viscosity is 36.53 cP, and its BOD is 8.51 ppm according to physicochemical analysis. These fluid properties comply with bio-hydraulic and mineral-based hydraulic fluid ASTM standards. This indicates that the bio-hydraulic fluid is suitable for various automotive and industrial hydraulic functions.