Esterification optimization of underutilized Ceiba pentandra oil using response surface methodology

In recent years, the utilization of non-edible feedstock particularly high free fatty acid (FFA) containing Ceiba pentandra oil (CPO) has acquired an immense attention among researchers for biodiesel production. In this work, sulfuric acid-based esterification process was conducted on underutilized CPO and the process was optimized by the application of response surface methodology (RSM) using central composite design (CCD). A total of 20 experimental runs with six centre points were conducted to reduce the acid value of CPO and the effect of three independent process variables such as reaction time (30-90 min), H2SO4 catalyst concentration (0.5-1.5 vol%), and methanol to CPO volumetric ratio (1:2-1:4 vol/vol) was investigated with constant reaction temperature (60 degrees C) and stirrer speed (450 rpm). A quadratic model was suggested and the interaction between the selected process variables on the response acid value was evaluated using the generated 2D-contour and 3D-response surface plots that leads to the prediction of optimized esterification condition for maximum acid value reduction. Under the optimized process conditions, the acid value of underutilized CPO was reduced from 14 mg of KOH/g oil to 2.08 mg of KOH/g oil. Fourier transform infrared spectroscopy (FTIR) was performed to analyze the functional group modifications in raw and esterified oil.