An insight into biodiesel production from canola oil by homogeneously catalysed transesterification reaction in the presence of ethanol.
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Date
2021-04
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Abstract
The massive decline of fossil fuel resources in addition to the steady increase in the energy consumption
rate over the past century has spurred research interest in alternative and renewable energy sources. A promising and sustainable alternative to fossil fuels is biodiesel. To raise market competitiveness for biodiesel, it is necessary to develop a cost-effective and technical processing schemes, to identify key related design criteria and optimize performance. In this study biodiesel is synthesized via transesterification reactions, through which triglycerides (vegetable oils) are converted to their alkyl esters (biodiesel) and glycerol as a by-product. This researched is aimed to investigate the homogenous catalysed transesterification reactions for biodiesel production using two different base catalyst, potassium hydroxide and sodium hydroxide, in the presence of canola oil and ethanol. The combination of the experimental conditions used to determine the optimal biodiesel yield was obtained by using the Box-Behnken experimental design. The Box-Behnken design was chosen as it generates a higher order response surfaces using fewer required runs than a normal factorial technique. The process variables that were considered for biodiesel production were the alcohol/oil molar ratio, catalyst loading, reaction temperature and the reaction time. Hence, the optimum conditions for biodiesel production through a homogenously catalysed transesterification reaction was proposed. The reason these process variables were chosen, were due to these variables having the largest impact on the production of biodiesel. The feedstock oil (canola oil) of this study had an acid number of 0.129 mg KOH/g, this ensured that a single step transesterification process could be utilised. An optimum yield of canola oil biodiesel produced using potassium hydroxide was 94.78%, while an optimum yield for canola oil biodiesel produced with sodium hydroxide was 95.78%. The biodiesel produced using the optimum experimental conditions were subject to basic property testing (such as density, viscosity, acid value, pH, pour point, flash point, etc), and blending with kerosene to produce bio-jet fuel (The 10% blend (BK10) which is 10% biodiesel and 90% kerosene and 20% blend (BK20) consisting of 20% biodiesel and 80% kerosene). The biodiesel samples (KOH and NaOH) met most of the ASTM standards, however the viscosity of the samples were 14.89 mm2/s and 10.10 mm2/s for KOH and NaOH biodiesel respectively which was beyond the 6 mm2/s limit, hence further modification would be required before it can be utilised for diesel engines. It can be noted that this research found that NaOH would be better suited for biodiesel production in the presence of canola oil, as it produced a higher yield of ethyl ester of 95.78% and the viscosity of 10.10 mm2/s obtained was closer to the acceptable range. The jet fuel samples did not meet all ASTM standard requirements; hence these are not recommended for use in an engine without further modification. A superficial feasibility study was conducted due to the lack
of studies regarding the cost analysis of biodiesel with the raw materials mentioned in this study, this study determined that the main factor influencing the economic viability of biodiesel is the feedstock cost.
Description
Masters Degree. University of KwaZulu-Natal, Durban.