RGO@SnO2/ZnO nanocomposite as a highly reactive heterogeneous catalyst toward biodiesel synthesis by electrolysis procedure: Central composite design optimization

Abstract

This paper highlights the incorporation of catalyst choice, feedstock type, and production technique for biodiesel production, thereby addressing existing gaps in the current research. In this sense, the rGO@SnO2/ZnO nanocomposite as a novel heterogeneous catalyst was prepared and employed to generate biodiesel from waste frying oil (WFO) by electrolysis approach for the first time. The structural attributes of rGO@SnO2/ZnO nanocatalyst were evaluated by several analyses. According to these analyses, rGO@SnO2/ZnO nanocomposite has a specific area of 61.428g/m2 and appropriate functional groups. Additionally, a CCD-based RSM approach was employed for achieving the highest biodiesel yield in optimal conditions (MeOH/WFO molar proportion=12:1, reaction time= 40min, voltage=40V, and catalyst concentration= 3.5wt.%) was 96.47%. Likewise, the yield of biodiesel decreased from 96.58 to 88.36% after seven reuse cycles, which reveals the substantial stability of rGO@SnO2/ZnO nanocomposite in the transesterification procedure. Moreover, the thermodynamic behavior of biodiesel synthesis indicated that the transesterification employing rGO@SnO2/ZnO nanocomposite is endothermic. The activation energy and Arrhenius factor for the transesterification of WFO to biodiesel utilizing rGO@SnO2/ZnO nanocatalysts were determined to be 51.59kJ/mol and 6.67×105min-1, respectively. Due to the high biodiesel yield and remarkable reusability, rGO@SnO2/ZnO nanocomposite is strongly recommended for the transesterification procedure.