Transesterification of Castor Oil for Biodiesel Production Using H2SO4 Wet Impregnated Snail, Egg and Crab Shell Catalyst.
Authors: Nwanekwu Akunna Maureen  , Omuku Patrick Enuneku  , Okoye Patrice-Anthony Chudi  , Vincent Ishmael Egbulefu Ajiwe  , Omuku Patrick Enuneku  , Onyeije Ugomma Chibuzor  
Published: June 2024

Biodiesel does not only provide a sustainable alternative for diesel fuel but also enables the transformation and utilization of wastes into high value products. Therefore, the aim of this study is to use heterogeneous catalysts derived from wet-impregnated snail, crab and egg shell waste in the production of biodiesel using castor oil. The use of castor oil as the preferred non-edible oil is due its high ricinoleic acid concentration as well as its high solubility in alcohol. The uncalcined egg, snail and crab shell catalysts were identified as E, S and C respectively while CS800oC/H2SO4, CC900 oC/H2SO4, and CE900 oC/H2SO4 represents calcined/impregnated snail, crab and egg shell catalysts respectively. The BET and SEM were used to determine the surface morphology and microstructure of the catalysts while the structure of the crystalline materials and the elemental composition of the catalysts were determined using the XRD and XRF respectively. GC-MS was used to analyze the free fatty acid composition of the oil and FTIR to obtain the organic and polymeric materials present. The physical and chemical analysis of the crude castor oil was carried out so as to determine the percentage of FFA contained in the oil. Each of the calcined/impregnated snail, crab and egg shells were reacted singly with castor oil in the biodiesel production where CS, CC and CE are acronyms that stands for castor oil-snail shell, castor oil-crab shell and castor oil-egg shell biodiesel products respectively. All three castor oil biodiesel products were produced at various specifications or reaction conditions lettered from A – I usually written as a subscript after the biodiesel product and as a result, 27 samples of biodiesel was produced. The optimal conditions required for the production of the biodiesel were obtained and the fuel properties of all 27 samples of biodiesel produced were determined. The crude castor oil gave acid value and FFA of 5.87mgKOH/g and 3.25 respectively which were above the ASTM standards at 0.4 – 4 mgKOH/g and 0.2 – 2 respectively. The highest surface area was produced from calcined/impregnated crab shell at 170.21 m 2/g. The result from the FTIR analysis showed the presence of O – C – O and O – H bonds in the uncalcined spectra and a strong S ═ O bond after calcination/impregnation. Castor oil-egg shell biodiesel product obtained with H-specification (CEH) produced the highest biodiesel yield of 95.3 %. This was obtained at optimal conditions of 1:12 oil to methanol ratio, 5 wt% catalyst loading, 60 OC reaction temperature for 60 min reaction time. Results from the characterization of biodiesel products obtained showed 70, 9.80 mm2/s and 945 kg/m3 as maximum values of cetane number, kinematic viscosity and density traced from castor oil-egg shell biodiesel product obtained with H-specification (CEH), castor oil-snail shell biodiesel product obtained with A-specification (CSA) and castor oil-egg shell biodiesel products obtained with A-specification (CEA) respectively.