2Department of Chemical Engineering, Nnamdi Azikiwe University, Awka, NIGERIA
3Department of Pure and Industrial Chemistry, University of Nigeria, Nsukka, NIGERIA
Abstract
This paper investigates the significance of the operating conditions on the production of methyl esters from seed oils of sweet almond (Prunus amygdalus), African star apple (Chrysophyllum albidium) and African pear (Dyacrodes edulis). The effects of various process conditions such as catalyst amount, reaction temperature, methanol/oil molar ratio and reaction time on biodiesel yield and its viscosity were studied. The result shows that African pear seed oil methyl ester (APSOME), sweet almond seed oil methyl ester (SASOME) and African star apple seed oil methyl ester (ASASOME) production is optimized at a mixing rate of 140rpm, atmospheric pressure, temperature of 65˚C, reaction time of 65 minutes, methanol to oil molar ratio of 8:1 and catalyst concentration of 1.5wt%, 2.0wt% and 2.0wt% respectively. The alkaline methylic transesterification gave 94.50%, 95.50% and 85.70% yields of esters with viscosity of 2.60mm2/s, 2.45mm2/s and 2.40mm2/s respectively. The physico-chemical properties of the seed oils showed improved fuel qualities upon transesterification compared well with ASTM and EN standards. The GC-MS result showed mainly unsaturation characteristics. A total of 37.74% saturated fatty acid (SFA), 41.42% monounsaturated fatty acid (MUSFA) and 13.90% polyunsaturated fatty acids (PUSF) were found to be contained in SASOME. ASASOME contains 27.71% SFA, 53.30% MUSFA and 18.99% PUSFA while APSOME contains 14.78% SFA, 75.50% MUSFA and 6.41% PUSFA. These results attest the viability of the selected tropical seed oils in biodiesel production.