A green recyclable SO3H-carbon catalyst derived from glycerol for the production of biodiesel from FFA-containing karanja (Pongamia glabra) oil in a single step

•Production of biodiesel from high FFA oils requires a two-step process.•Developed single-step process using glycerol-based solid acid catalyst.•Economically strengthens the biodiesel industry with new application to glycerol.•The catalyst reduces the effluent by replacing both H2SO4 and alkali catalysts.

Simultaneous esterification and transesterification method is employed for the preparation of biodiesel from 7.5% free fatty acid (FFA) containing karanja (Pongamia glabra) oil using water resistant and reusable carbon-based solid acid catalyst derived from glycerol in a single step. The optimum reaction parameters for obtaining biodiesel in >99% yield by simultaneous esterification and transesterification are: methanol (1:45 mole ratio of oil), catalyst 20 wt.% of oil, temperature 160 °C and reaction time of 4 h. After the reaction, the catalyst was easily recovered by filtration and reused for five times with out any deactivation under optimized conditions. This single-step process could be a potential route for biodiesel production from high FFA containing oils by simplifying the procedure and reducing costs and effluent generation.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slide