Synthesis and characterization of triol based bio-lubricant from waste cooking oil

The increased price and utility of fossil fuels require an alternate source of energy, as fossil fuels are non-degradable causing environmental pollution. So biodegradable lubricants were developed as an alternative to the existing one. Bio-lubricants prepared from vegetable oils are expensive and eco-friendly. The production lubricants from waste cooking oils are inexpensive compared to their virgin oil lubricants. In the present study, the bio-based lubricants were synthesized from polyol like trimethylolpropane (TM P) and waste cooking oil fatty acid by esterification method in the presence of an acid catalyst. Because the waste cooking oil may contain a huge amount of free fatty acids, so it cannot directly be used with the base catalysts. The conversion efficiency of the esterification process is affected by the molar ratio of reactants and the amount of catalyst. The best conversion efficiency was obtained 89% from a molar ratio of 3.5:1 waste cooking oil fatty acid and TMP in presence of 1.5 wt% of para toluene sulfonic acid (pTSA) at 120-130 °C for 5 h. The synthesized TMP based ester was characterized by 1HNMR and IR, Physico-chemical properties such as density, specific gravity, acid value, kinematic viscosity at 40 °C & 100 °C, viscosity index, cloud point, pour point, flash point, fire point and copper strip corrosion were studied by standard ASTM methods. TMP based ester was showing better lubricant properties compared to commercial oil (ISO VG 32) lubricant produced from mineral-based oils. Thus, it can be used as a bio lubricant base stock for industrial applications.