Experimental design and kinetic study of ultrasonic assisted transesterification of waste cooking oil over sulfonated carbon catalyst derived from cyclodextrin

•Biodiesel was produced from waste cooking oil using a novel sulfonated carbon catalyst derived from cyclodextrin.•2k factorial and Box–Behnken designs were applied.•Maximum yield of biodiesel 90.8% was achieved by ultrasonic assisted transesterification.•Catalyst can be reused without any serious reduction of biodiesel yield.•Activation energy was 11.64 kJ/mol.

The ultrasonic assisted biodiesel production from waste cooking oil using heterogeneous catalyst was studied. The sulfonated carbon was synthesized via one-step hydrothermal carbonization. The catalyst was characterized by BET, XRD, PSD, SEM-EDX, TGA, FT-IR, XPS and TPD. The surface area, pore size and acid density were found to be 8.2 m2/g, 22.1 nm and 1.87 mmol/g, respectively. The significant parameter and optimum condition for biodiesel production were investigated using 2k factorial and response surface methodology, respectively. The catalytic experimental results showed that catalyst loading of 11.5 wt.%, reaction time of 8.8 min and reaction temperature of 117 °C provide the maximum biodiesel yield up to 90.8% in the ultrasonic assisted biodiesel production. For the conventional stirring method, the highest biodiesel yield of 89.5% was obtained with the optimum condition: catalyst loading of 12.3 wt.%, reaction time of 16.1 h and reaction temperature of 136 °C. The catalyst can be reused up to 12 cycles with slight reduction in biodiesel yield after regeneration. The activation energy of 11.64 kJ/mol was obtained from kinetic model for transesterification.

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