Abstract
The study emphasized the use of the mixed oil (MO) extracted from Elaeis guineensis and Thai Red oilseeds for the synthesis of biodiesel using a derived bio-base catalyst from calcined Littorina littorea shell powder. The MO properties were determined with a view to examine its quality for biodiesel production. The derived calcined catalyst was characterized using scanning electron microscopy (SEM), X-ray fluorescence (XRF), Fourier transforms infrared spectroscopy (FTIR), BET adsorption analysis, and Hammett indicator. Process optimization of biodiesel synthesized was carried out by considering four constraint variables: reaction time (60-80 min), catalyst conc. (2-6% wt.), reaction temp.(55-75 °C), and ethanol/oil molar ratio (E-OH/OMR) (4-8 vol./vol.) using design expert STAT EASE 360. For the rate of reaction, degree of disorderliness, and the activation energy of the transesterification process, kinetics and thermodynamic parameters were considered using Eyring Polanyi and Gibb's Duhem equations, while the qualities of biodiesel as well as its economic appraisal were also carried out. Results obtained showed the API gravity ratio of the mixed oil of 2:3, which indicated a perfect blend ratio. Statistical analysis validation via response surface methodology indicated a biodiesel yield of 98.90% (wt./wt.) was obtained at 69.83 (min), 5.86% (wt.), 68.17 °C, and 7.04 (vol./vol.). Kinetic parameter evaluation showed the activation energy (Ea) of transesterification of the mixed oil to biodiesel to be 55.44 kJ mol-1 while thermodynamic parameters (Gibb's free- ΔGθ)ΔGθ)<math> <mrow><mrow><mo>Δ</mo> <msup><mi>G</mi> <mi>θ</mi></msup> </mrow> <mo>)</mo></mrow> </math> were obtained as follows: 184.87 kJ mol-1, 179.77 kJ mol-1, and 174.67 kJ mol-1, at enthalpy ( ΔHθ)ΔHθ)<math> <mrow><mrow><mo>Δ</mo> <msup><mi>H</mi> <mi>θ</mi></msup> </mrow> <mo>)</mo></mrow> </math> value of 53.38 kJ mol-1 and entropy (ΔSθ)(ΔSθ)<math><mrow><mo>(</mo> <mrow><mo>Δ</mo> <msup><mi>S</mi> <mi>θ</mi></msup> </mrow> <mo>)</mo></mrow> </math> of -509.64 J mol-1, respectively. Catalyst reusability test was altered at 7th cycles, while the qualities of biodiesel were found comparable with biodiesel recommended standards (ASTM D6751 and EN 14214).