Yield optimization and fuel properties evaluation of the biodiesel derived from avocado pear waste

This work used a solvent extraction technique to obtain oil from avocado pear seeds and peels. Next, this extracted oil was pre-treated with methanol and H₂SO₄ to decrease its free fatty acids below 1.0 wt%. A central composite design was employed to optimize biodiesel production via trans-esterification between the pre-treated extracted oil and methanol catalyzed by NaOH. The optimum biodiesel yield recorded was 91 wt% at a CH₃OH/pre-treated extracted oil molar ratio of 8:1, catalyst dosage of 0.7 wt%, temperature of 65 °C, time of 60 min, and agitation speed of 400 rpm. The biodiesel was mixed with the fossil diesel at different mass ratios, and the diesel engine tests were carried out. Engine torque, speed, fuel consumption rate, thermal efficiency, brake power, and emissions were assessed. The results showed that the engine used less than 20 % biodiesel mixture to generate the same amount of useful work compared to fossil diesel. Overall, the 20 % biodiesel mixture exhibited the best engine performance among all biodiesel/fossil diesel ratios at a torque of 70 N m, speed of 1900 rpm, brake thermal efficiency of 0.631, brake specific fuel consumption of 0.129 kg/kW h, brake power of 13.9 kW and very low emissions.