Transesterification of mustard oil to biodiesel using activated carbon/Fe2(MoO4)3/K2CO3 as a novel heterogeneous nanocatalyst: Box-Behnken design-based optimization and Gaussian process regression

In this study, activated carbon/Fe2(MoO4)3/K2CO3 was synthesized as a novel heterogeneous catalyst and used for the first time for biodiesel production from mustard oil. The synthesized catalyst was appraised by Brunauer-Emmett-Teller (BET), Energy-dispersive X-ray analysis (EDX)/Map, Scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and Raman analyses. The effect of operating parameters including methanol-to-mustard oil ratio (9:1–27:1), temperature (50–75 °C), catalyst concentration (1–6 wt%), and reaction time (1–6 h) on the biodiesel yield was investigated. The optimization of transesterification operating parameters through Response Surface Methodology (RSM) utilizing Box-Behnken design revealed a peak yield of 96.36 ± 0.1 %. This optimal yield was attained under the following conditions: a methanol-to-oil ratio of 21:1, a temperature of 65°C, a catalyst concentration of 4 wt%, and a reaction time of 4 hours. Furthermore, Gaussian Process Regression (GPR) was employed for the prediction of the biodiesel production yield and a satisfactory agreement was observed between the results of RSM and GPR. Reusability experiments indicated that the synthesized catalyst can be regenerated and reused in 4 transesterification reactions without experiencing a significant decrease in yield. The physical properties of biodiesel derived from mustard oil were examined, and it was observed that they were in agreement with ASTM D6751 and EN 14214 standards. According to the results of this study, it can be concluded that biodiesel production from mustard oil using the novel activated carbon/Fe2(MoO4)3/K2CO3 heterogeneous catalyst can be considered as a promising approach for generation of clean energy.