Heterogeneous Biodiesel Catalyst from Steel Slag Resulting from an Electric Arc Furnace

Abstract

Biodiesel is one of the most environmentally friendly and renewable fuels, as it is a non-polluting fuel and is made from living resources, such as vegetable oils. The steel industry generates a variety of solid wastes, including electric arc furnace slag (EAFS). The synthesis of biodiesel from waste sunflower cooking oil was examined in this study, utilizing EAFS as a catalyst, which mainly contains ferric and ferrous oxides, calcium oxide, and silica. To evaluate their impact on biodiesel production, four independent variables were chosen: temperature (50–70 °C), catalyst loading (1–5%), methanol-to-oil (M:O) molar ratio (5–20), and time (1–4 h). The response surface methodology (RSM) was used to examine the impact of independent variables on reaction response, which is the biodiesel yield. This process was carried out using a design expert program by central composite design (CCD). A model was constructed, and showed that the biodiesel yield was directly proportional to all independent reaction parameters. The predicted model’s adequacy was investigated using analysis of variance (ANOVA), which showed that it is an excellent representative of the results. The optimization of reaction conditions was investigated in order to maximize biodiesel yield at minimal reaction temperature and time, achieving a 94% biodiesel yield at a 20:1 M:O molar ratio, 5% catalyst loading, 55.5 °C reaction temperature, and 1 h reaction time.