Comparison for raw and commercial castor oil in the production of biodiesel
Authors:   , Masango Sandile Brendon 
Published: September 2024

The development of industries is associated with higher pollution levels and higher fuel costs. The research on clean energy helps to lessen the reliance on fossil fuels, the ozone layer’s depletion, and the release of hazardous pollutants. The development of renewable energy sources increases energy independence and lessens the harm that fossil fuels do to the environment in the Republic of South Africa (RSA), one of the African Nations. The main the challenge is the fragility of crude oil prices, high unemployment, worries about climate change, and the requirement for the continent's developing economies to use their resources sustainably are what motivate the establishment of a successful biodiesel (Fatty Acid Methyl Ester) business. Particularly in recent years, biodiesel has evolved into one of the most popular biofuels for fuel substitution with biodiesel. In this study, homogeneous alkaline transesterification was used to produce methyl ester biodiesel (FAME) from refined or commercial castor oil (CCO) and raw castor oil (RCO) feedstock. The obtained results were compared to those evaluated, which produce better yield by varying essential parameters, which include reaction temperature, catalyst concentration, and alcohol: oil molar ratio at a constant period of 90 minutes. The effect of potassium hydroxide (KOH) as a catalyst between raw and refined castor oil was compared. The result revealed the performance of the KOH catalyst on raw castor oil yields 98.49% FAME, which was higher than the refined castor, oil which yield was 97.9% FAME. The optimal conditions was reaction temperature 45 oC, methanol:oil mole ratio 1:9, and catalyst concentration 0.625 % w/w, were obtained from refined castor oil were applied to raw castor oil because of the same properties. It was found that the yield of raw castor oil was 98.49% which is higher to that of refined castor oil which is 97.9%. General Rate Equation, Pseudo first order model, Second order model, and Modified-Second order model are the kinetics models that were evaluated and discussed. The kinetic models behavior is that the rate of reaction r increase with the increase in temperature, at the maximum reaction temperature of the study 343.15 K, 5.1×10-07 (K.mL/mol.min) General Rate Equation, 5.7×10-08 (K.mL/mol.min) Pseudo first order, 6.9×10-07 (K.mL/mol.min) Second order model, and 61.4×10-04(K.mL/mol.min) Modified-Second order model. Pseudo first order model and Second order model were the best fitted kinetic models then PFO shows to be best kinetic model for the study by measuring absolute error 1.4×10-04 and relative error 0.999 was very low. The methodology adopted for the study include fuel quality of castor oil (raw and commercial) and produced biodiesel were tested for physicochemical properties. Physicochemical properties and ASTM standard.for raw castor oil :- kinematic viscosity 1.98 (cSt) @50 oC, ASTM D445 , Ash 0.03 (g), ASTM D874, Flash point 114 oC, ASTM D93, sulphur 0.64 ppm, ASTM D5453, density 920 kg/m3 , ASTM D1298/0452, water content 0.05 %, ASTM D2709, and calorific value 44121kJ/kg, ASTM D6751, while for commercial castor oil:- kinematic viscosity 2.98 (cSt) @50 oC, ASTM D445, Ash 0.05 (g), ASTM D874, Flash point 116 oC ASTM D93, sulphur 0.65 ppm, ASTM D5453, density 960 kg/m3 , ASTM D1298/0452, water content 0.04 %, ASTM D2709, and calorific value 44121kJ/kg ASTM D6751. The study is also assessed for economic feasibility to determine if it will be profitable. The process design comprises the main processing unit, reactor, separator, mixing tank, centrifugal pumps and heat exchangers. In this study only, reactor was simulated using ASPEN Plus version 11 software utilizing the generated data from the laboratory. Economic feasibility was based mostly on the reactor and scaling up to plant scale. The cost of biodiesel production per year is R 205391.34/ year, sales cost is R 2464696.08/ year which gives a profit of R 1117077.48/ year which proves economic feasibility of the study. It was concluded that raw castor oil can be suitable used in the process of producing biodiesel since it exhibit higher yield. It was recommended that one must use the generated data to up-scale the process and design other unit in details. Asides vegetable oils, castor seeds are among the identified raw materials from which raw castor oil can be extracted for biodiesel production because it has high oil content up to 60%