Moringa polyesters as eco-friendly lubricants and its blends with naphthalenic lubricant

Abstract Due to the toxicity and low biodegradability, mineral lubricants have been sharing space with green lubricants. Moringa oleifera can grow naturally in dry regions with subtropical climates and the oil, rich in unsaturated compounds (79.87 %), may be a potential feedstock for fuel and lubricant base stocks. Moringa oil was hydrolyzed and then esterified with polyols, trimethylolpropane (MTMPE) and pentaerythritol (MPEE), in the temperature range of 130–140 °C. P-toluene sulfonic acid (p-TSA) was used as the catalyst. The products obtained were characterized using 1H and 13C NMR, IR, and mass spectral techniques. The main physicochemical properties, the thermal behavior and toxicity against Artemia salina of products were evaluated. In addition, blends with the naphthenic lubricant, NH10, were prepared with 20 %, 35 %, and 50 % of the moringa esters. The synthesized samples have high viscosity indices (VI = 170) and they were found to be non-toxic against A. salina (LC50>1000 ppm). MTMPE presented higher thermal stability and showed a melting point of -38.5 °C, which reveals its potential for applications in very low temperatures. Blends showed high viscosity indices and reduced toxicity compared to pure NH10. The study revealed that moringa esters are interesting to be applied as environmental friendly lubricants or additives.