Upgrading MnO2@CuO with GO as a superior heterogeneous nanocatalyst for transesterification of dairy waste oils to biodiesel through electrolysis procedure

In this research, the electrolysis procedure was employed to synthesize biodiesel from dairy waste oil (DWO) utilizing MnO2@CuO and MnO2@CuO@GO as novel heterogeneous nanocatalysts. The structural attributes of MnO2@CuO and MnO2@CuO@GO nanocatalysts were scrutinized utilizing Brunauer-Emmett-Teller (BET), Field Emission Scanning Electron Microscopy (FESEM), Mapping, Energy Dispersive X-ray (EDX), Transmission Electron Microscopy (TEM), Temperature-Programmed Desorption (CO2/TPD), Raman, X-ray Diffraction (XRD), and Fourier Transform Infrared Spectroscopy (FTIR) analyses. Further, Proton Nuclear Magnetic Resonance (H NMR), Gas Chromatography–Mass Spectrometry (GC-MS), and FTIR spectra were utilized to characterize the chemical structure of biodiesel and DWO. According to the Box-Behnken Design statistical method, the highest biodiesel yield utilizing MnO2@CuO and MnO2@CuO@GO nanocatalysts was 94.15 and 98.07 %, respectively, which were obtained after 52.64 and 49.3 min, respectively. According to the results, MnO2@CuO@GO has a higher ability to generate biodiesel compared to MnO2@CuO. After 7 consecutive reuse cycles, the yield of biodiesel using MnO2@CuO and MnO2@CuO@GO nanocatalysts was 80.14 and 90.77 %, respectively, demonstrating that MnO2@CuO@GO is much more stable than MnO2@CuO. The kinetics of biodiesel generation showed that the reaction between DWO and methanol in the presence of MnO2@CuO@rGO is non-spontaneous and endothermic (ΔHo = 47.54 kJ/mol). In general, MnO2@CuO@GO, because of its easy synthesis, high biodiesel efficiency, and remarkable stability, is considered as a promising catalyst for industrial applications.