Optimization of Biodiesel production from crude cottonseed oil using wood ash as a catalyst

Abstract

World major sources of fuel are non-renewable fossils expected to be depleted. Availability of sustainable energy is a complex socially, technologically, economically and politically. Researchers have concentrated on the use of methanol and mineral catalysts although ethanol and wood ash have potential but available, affordable, environmentally friendly and reliable. The main objective was to optimize production of biodiesel using crude cottonseed Oil and wood ash. The Specific objectives were to; undertake pre-processing and produce biodiesel; determine optimum conditions for the yields; design suitable process and; model the reaction. Cottonseed was characterized, oil extracted, filtered, analyzed and transesterified, chemical and physical properties tested. Characterization results were lint, seed and waste averaged 35%, 60% and 5% respectively while; oil 20%. Mole ratios of alcohol to oil were varied from 9:1-12:1 with temperature at 60 ◦ C and wood ash load ranges between 2.4- 6.05 g/l of oil and time ranged of 2-3 hours. Separation was undertaken, phases noted and esters washed using warm acidic water (30◦C and Ph.5). Refined soya bean oil was used as a control experiment and yields recorded. Eight experiments were performed according to the fractional factorial design and results analyzed to develop a Linear Regression equation. The variables were varied to get the optimum conditions to which a model was developed. The optimal conditions for obtaining maximum yield of 96.5% and meeting acceptable quality of biodiesel is: alcohol to oil mole ratio of 12:1, catalyst load of 6.05 g/l and time of 3 hours. The model result was linear equation with coefficient of Mole ratio being 1.8 while that of time being least at 0.0125.Physical and chemical properties per results compared against Standard for bio-fuel proved positive. The research proved the viability to optimize biodiesel production using wood ash catalyst while varying: temperature; mole ratios and wood ash load. The general objective was met with results showing similarity n properties with those of soya bean and mineral catalysts. Wood ash and ethanol proved to be substitutes including Other recommendations as follows: characterization of various wood ash sources; policy interventions to increase the production of feedstock to sustain supply; undertake the process at lower temperatures to save on energy; open batch system the suitable this process; more studies to establish various characteristics of wood ash.