Effects of Process Variables and Petro-Diesel Blend on the Yield and Fuel Properties of Tiger Nut Oil Biodiesel

Umeuzuegbu J.C.

Tiger nut oil biodiesel, transesterification, characterization, ASTM method, process parameter, biodiesel yield.

Though, biodiesel is now gaining more grounds as the best alternative replacement for fossil fuel,this conception could only come true if the cost of biodiesel is competitive with that of fossil fuel. This research work focused on effects of process variables and petro-diesel blend on the yield and fuel properties of tiger nut oil fatty acid methyl ester (TNOFAME) or biodiesel. Tiger nut oil (TNO) was solvent extracted using n-hexane, and then characterized based on American Society for Testing and Materials (ASTM) method. The fatty acid profile was determined using gas chromatography mass spectrometry while the functional group of the oil was analyzed using Fourier transform infrared spectroscopy. The effect of process parameter on the yield of TNOFAME was investigated using one factor at a time method. The TNO was pretreated to reduce the free fatty acid below 1% and then transesterified using methanol in the presence of sodium hydroxide (NaOH) catalyst. The fuel properties of the TNOFAME produced were determined based on ASTM standards. The tiger nut oil biodiesel was blended with #2 diesel oil on a percentage volume ratio of biodiesel to diesel 0, 20, 40, 60, 80 and 100% designated as B0, B20, B40, B60, B80 and B100 respectively. The effect of petro-diesel blend on the fuel properties of TNOFAME was carried out by testing the fuel properties of different blends, B0, B20, B40, B60, B80 and B100 and comparing the properties with those of B100 and B0. The process parameters, methanol to oil molar ratio, catalyst concentration, reaction temperature, reaction time and agitation speed greatly affected the biodiesel yield as their increase resulted in the increase of biodiesel yield until the optimum parameter was attained when the yield started decreasing. The experimentally determined properties of the TNOFAME; density, kinematic viscosity, cetane number, flash point, cloud point, water and sediment, calorific value, iodine value, pour point, refractive index gave the values, 870Kg/m³, 4.60mm²s^-1, 61, 160⁰C, 7⁰C, 0.03%, 0.45, 36.2MJ/Kg, 65.2, gI₂/100g, 4⁰C, 1.446 respectively. By blending of biodiesel, B100 with petro-diesel B0, both fuels impart their respective good fuel properties, low viscosity, low density, low cloud and pour point and high calorific value of petro-diesel, high cetane number, high flash point, high lubricity and biodegradable nature of biodiesel on the blends, B20 B40, B60, and B80. However at present only blends of low biodiesel content (≤ 20%) possess equivalent fuel properties of diesel and as such suitable for use in compression ignition engine without engine modification.