Kesan pelbagai frekuensi ultrabunyi ke atas penghasilan biodiesel daripada minyak jarak pagar

Abstract

Biodiesel production from renewable feedstock is a viable alternative to reduce both the depletion of fossil fuel and greenhouse gas emissions. Biodiesel can be produced from vegetable oils such as palm oil. However, jatropha curcas oil can be most suitable source with potentially lower cost. The objective of this study was to determine the effect of ultrasound on the reaction rate, chemical reaction model and efficiency of biodiesel production from jatropha curcas oil. The production of biodiesel was done by the process of transesterification reaction using various types of solvents such as methanol, ethanol, isopropyl alcohol and tert-butanol and potassium hydroxide (KOH) as catalyst. Three different frequencies of ultrasound namely 35 kHz, 42 kHz and 48 kHz were used. The results showed that the highest percentage of biodiesel obtained was 97.80 % at 35 kHz, at molar ratio of isopropyl alcohol to jatropha curcas oil of 8 : 1, KOH concentration of 0.5 %, reaction temperature of 60 °C and the reaction time of 15 minutes. At frequency of 42 kHz and 48 kHz, lower biodiesel yields were found. An irreversible second order reaction model was observed with the calculated activation energy of 14.372 kJ/mol. The best engine performance for a mixture containing 40 % of jatropha biodiesel in diesel oil (B40) resulted brake specific fuel consumption of 0.19 kg/kWh and the brake thermal efficiency of 30.21 %. The exhaust emission test showed 0.17 % of CO; 3.3 % of CO2; 1428 ppm of NOx and 22 % O2. The followings are the physical properties of biodiesel tested : viscosity (4.0 mm2/s); density (900 kg/m3); flash point (110.5 °C) and cetane number (51). The testing complies with USA ASTM D 6751 and European standards EN 14214 2003. The study showed that the application of ultrasound enhanced the biodiesel conversion of jatropha curcas oil.