Integrated global optimization and process modelling for biodiesel production from non-edible silk-cotton seed oil by microwave-assisted transesterification with heterogeneous calcium oxide catalyst

Abstract

Second generation feedstock like non-edible seed oil, used cooking oil, and animal fats for biodiesel production has huge potential, yet these feedstocks have been underutilised. In this current study, non-edible Ceiba pentandra seed oil (CPSO) was used to produce biodiesel. Ceiba pentandra seed yielded an oil content of 18.6% after extraction. CPSO had 6.87% free fatty acid, 0.911 specific gravity, 98.9 g I2/100 g oil iodine value, 1.47 refractive index, 189.14 mg KOH/g oil saponification, 13.67% acid value, and 3.29 meq O2/kg oil peroxide value. CPSO was characterized using Fourier transform infrared spectroscopy (FT-IR) and gas chromatography-mass spectrometry (GC-MS) analysis. The free fatty acid value of CPSO was reduced to 0.83% using the esterification process at 60°C for 60 min with a 3:1 methanol to oil volumetric ratio, 5% sulfuric acid. The microwave-assisted transesterification process (MATP) was carried out by CPSO and methanol as reactants and calcium oxide (CaO) as a catalyst. CaO was characterised using FT-IR, scanning electron microscope, energy dispersive X-ray analysis, and Brunauer–Emmett–Teller analysis. To optimise the process variable of the MATP, response surface methodology was used, followed by an artificial neural network coupled with a genetic algorithm. At 270 W and 114 s reaction time, 0.3 wt.% CaO, and 18:1 alcohol to oil molar ratio, 97.4% biodiesel yield was obtained. FT-IR, GC-MS, 1H &13C Nuclear magnetic resonance, Heteronuclear single quantum coherence spectroscopy, and Heteronuclear multiple-bond correlation were used to characterise the biodiesel. In conclusion, CPSO has the potential to produce a large quantity of quality biodiesel by the application of the CaO catalyst.