Efficient production of biodiesel at low temperature using highly active bifunctional Na-Fe-Ca nanocatalyst from blast furnace waste

In this study, nanocatalysts for biodiesel production were prepared via wet impregnation of blast furnace dust (BFD) in Na2CO3 (Na-BFD) and CaCO3 (Ca-BFD) suspension solutions and calcination at 500 and 600 °C, respectively. Biodiesel yields of 100.0 wt% (Na-BFD500) and 98.3 wt% (Ca-BFD600) were achieved at 65 °C. Synthesized catalysts showed outstanding activity and recyclability, due to the transition of CaCO3, Na2CO3 and Fe2O3 to nanocrystals of NaFeO2 (29.9 nm), Ca2Fe2O5 (10.5 nm), CaO (100.1 nm) and Ca2Fe2O5 (50.0 nm). Na-BFD500 achieved 95.8 wt% biodiesel yield with 16 cycles, whereas Ca-BFD600 reached 94.1 wt% biodiesel yield with 7 cycles via magnetic separation. BFD containing convertible magnetic and active components (Fe2O3 and CaCO3) was an ideal raw material to synthesize catalyst for biodiesel production with high catalytic efficiency and easy separation. The study provided a practical utilization of industrial solid waste for biodiesel production.