Nonlinear Programming for Solvent Extraction of Jatropha Curcas Seed Oil for Biodesiel Production

Abstract

Nonlinear programming models of solvent extraction of Jatropha curcas oil that forms the thrust of this paper is uncommon in literature. The oil was extracted using two solvents (n-hexane and Isopropanol) at a powder weight to solvent volume of 1:5 and particle size of between 0.5mm and 0.75 mm. A randomized 31 set of central composite design comprising three factors (solvent composition(0 - 100% n-haxane), time of extraction(1 - 5hours) and extraction temperatures(40 - 60℃) at five levels were experimented. Oil yield, specific gravity, viscosity, free fatty acid (FFAs) and iodine value of the oil extracts were determined. Response equation of each of oil yield (R1), specific gravity (R2), viscosity (R3), FFA (R4) and iodine value (R5) in terms of solvent composition (X1), time of extraction (X2) and temperature (X3) were developed. These were formulated into a nonlinear programme that maximize oil yield and minimizes other four properties according to ASTM D6751-07b and EN 14214-2008 (E) standards for biodiesel production. The coefficients of determination (R 2 ) for the re- sponses equations were 1.000, 1.000, 0.953, 0.963 and 0.968 respectively. The nonlinear programme yields a maximum oil yield (R1) of 37.3507 %, R2 = 0.88597, R3 =39.771 , R4 = 2.1185 and R5 = 101.51, while the optimum operating conditions were X1 = 2 (100% n haxane), X2 =2 (5 hours ) and X3 = 2 (60℃). This study has clearly demonstrated the applicability of nonlinear mathematical programming in selecting extraction conditions for jatropha oil from its seed.