Application of Box–Behnken design in optimization of biodiesel yield from Pongamia oil and its stability analysis

• Optimization of biodiesel production from Pongamia oil using Box–Behnken design approach.
• Evaluation of fuel properties of Pongamia biodiesel and its blends with diesel.
• Measurement of stability characteristics of Pongamia biodiesel and its blends.
• Impact assessment of Pyrogallol on the induction period of Pongamia biodiesel.

The present paper implements the Box–Behnken response surface methodology for maximizing the biodiesel yield from Pongamia oil by optimizing the four process variables. A biodiesel yield of 98.4% was achieved with methanol/oil molar ratio (11.06:1) using KOH as catalyst (1.43% w/w) in 81.43 min at a temperature of 56.6 °C. But the major problem associated with Pongamia biodiesel is its poor oxidation stability. This paper also investigates the methodology to improve the oxidation stability characteristics of Pongamia biodiesel. The result of investigation show that the use of antioxidant Pyrogallol (200 ppm) significantly improve the induction period from 1.83 h to 6.5 h for Pongamia biodiesel while PB10 blend can maintain its stability without any antioxidant.