ACID AND BASE CATALYSED TRANSESTERIFICATION OF ALMOND (Prunus amygdalus) AND GRAY NICKER (Ceasalpinia bonduc) SEEDS OIL TO BIODIESEL.

Abstract

Biodiesel is a low-emission diesel substitute fuel made from renewable resources and waste lipid. As one of the most promising clean energy technology options, this research study, therefore examined the transesterification of almond (Prunus amygdalus) and gray nicker (Ceasalpinia bonduc) seeds oil using both acid and base- catalysed transesterification in order to assess their suitability, for biodiesel production. The seeds were dried, blended and solvent extracted with n-hexane to recover the oil which gave the yields of 47% and 22% for almond and gray nicker seeds respectively. Physico-chemical properties of the oil was determined for properties such as density, pH, colour, viscosity, flash point, fire point, smoke point, acid value, free fatty acid and iodine value. Hence, the free fatty acid of the almond seed oil was noted to be too high and subjected to pretreatment procedure using 1% sulphuric acid which significantly reduced the free fatty acid to 5.69mg/KOH/g. The extracted oil of gray nicker and the pretreated oil of almond seed were subjected to transesterification using both homogeneous catalyst (sodium hydroxide) and admixture of heterogeneous catalyst (CaO/MgO) in varying catalyst concentration. Other experimental conditions such as molar ratio methanol/oil, agitation speed and temperature were also investigated to established the optimum experimental conditions for the biodiesel production. The optimum experimental condition for biodiesel production with these seed oil as feedstocks were noted at reaction time 90 min, catalyst concentration 0.03g, weight of catalyst 1wt% of initial oil weight, molar ratio methanol/oil 5:1, agitation speed 1500rpm and reaction temperature 60oC for homogeneous catalyst, while for heterogeneous catalyst the condition noted were reaction time 90 min, catalyst concentration 0.03g, weight of catalyst 1wt% of initial oil weight, molar ratio methanol/oil 5:1, agitation speed 1500 rpm and reaction temperature 70oC. The biodiesel yield obtained for the admixture were 51.54% for almond and 64.78% for gray nicker oils. Chemical characterization of the biodiesel samples were carried out using Gas Chromatography Mass Spectrometer (GCMS) and Fourier Transform Infrared (FTIR) Spectroscopy. The fuel properties of the biodiesel were tested according to some set standards as stated by ASTM and European specification (EN) standards. It was noted that the fuel properties of the biodiesel were consistents with these standards.