Waste Cooking (Palm) Oil as an Economical Source of Biodiesel Production for Alternative Green Fuel and Efficient Lubricant

Here, a cost-effective route for the preparation of biodiesel (BD) from waste cooking oil (WCO) as an alternative eco-friendly fuel and lubricant via catalytic transesterification process using simple base catalyst was demonstrated. Physical and chemical characterization based on FT-IR, H-1-NMR, and C-13-NMR spectroscopy reveals that free carboxylic acid functionality successfully alters to methyl ester of same hydrocarbon chain during the reaction. The BD was characterized by its physical, fuel characteristics including density, viscosity, acid value, flash point, pour point, and foaming tendency, and compared with existing diesel fuel in accordance with ASTM test standard. Prepared BD showed excellent fuel efficiency with higher flash (142 degrees C) and fire point (147 degrees C) than the existing diesel fuel. In order to use these synthetic biodiesel esters as advanced green lubricants, their lubrication behavior was tested and compared with hydrocarbon base oil hexadecane (HD). The macrotribological results showed the biodiesel significantly reduced the coefficient of friction by a maximum similar to 43% and specific wear rate similar to 71% in comparison with that of HD at variable applied load. The lubricating efficiency of prepared BD was found to be a similar trend in microtribometric experiments with reciprocating sliding motion under variable loads with similar contact pressure (P-m similar to 1.36-1.95 GPa) as demonstrated in macrotribological rotating motion. Due to polar nature of biodiesel, it deposits on the contact interface and provides a thick molecular film, which may be responsible for enhanced tribological behavior compared with pristine hydrocarbon oil.

Automated summary

The study demonstrates a cost-effective method for preparing biodiesel from waste cooking oil, which serves as an alternative eco-friendly fuel and lubricant. The synthesized biodiesel exhibits excellent fuel efficiency and lubrication performance compared to conventional diesel fuel and hydrocarbon oils.