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.

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