Synthesis and characterization of Argania spinosa (Argan oil) biodiesel by sodium hydroxide catalyzed transesterification reaction as alternative for petro-diesel in direct injection, compression ignition engines

Abstract

In this research work, the optimization conditions for obtaining optimum biodiesel yield from argan oil as well as the quantification of degree of interactions between reactants and biodiesel yield were investigated by using a response optimization model and response surface methodology (RSM) respectively. Similarly, a regression polynomial model was used to develop a unified equation for predicting the expected yield of Argan biodiesel for different values of reactant variables and a regression coefficient of 92.56% was obtained. The Argan oil was extracted from its kernel by using a soxhlet extractor with hexane as extraction solvent and 54.50% oil yield was obtained. The fatty acid compositional analysis was done by using a Shimadzu GCMS QP2010 SE Gas-chromatograph-mass spectrometer. The spectrometer analysis shows that the oil has 80.90% of unsaturated fatty acid with oleic and linoleic acid constituting larger percentages respectively. A sodium hydroxide catalyzed transesterification reaction was used to convert the triglyceride in the oil to fatty acid methyl ester under standard conditions and the fuel properties of the oil and its ester were measured by using the American society for testing and materials (ASTM) procedures. A Fourier transform infrared spectroscopic (FTIR) technique was used for qualitative characterization of biodiesel functional groups in order to affirm the complete conversion of the oil into biodiesel. Results showed that the cold flow behaviour in terms of cloud point, pour point, cold filter plugging point (CFPP) and Low temperature flow test (LTFT) and critical properties such as cetane number, calorific value, iodine value, density, flash point, ash percentage and carbon residue of the Argan biodiesel showed a good agreement with ASTM D6751-07b and European committee for standardization (EN 14214) standard requirements. Hence, its application in compression ignition engines will pose no threat as far as performance, combustion and emission qualities are concerned. Finally, the Argan biodiesel has a very high higher heating value (HHV) of 40,665 kJ/kg which is very uncommon of other vegetable oils methyl esters and thus facilitate better heat release during combustion and improves engine performance.