Utilization of Waste and Under-utilized Pongamia pinnata Seed Oil for Acquiring Maximal Process to Get Ameliorate Yield of Biodiesel Through Response Surface Methodology

Abstract

The aim of this study was to use the under-utilized vegetable seed oil and produce high and better yield of biodiesel. The response surface methodology (RSM) was used, based on central composite rotatable design (CCRD), to optimize four trans-esterification reaction variables for getting high yield: catalyst concentration (CC; 0.25–1.0 %), reaction temperature (RT; 45–65 °C), CH3OH-to-oil molar ratio (6:1–12:1) and reaction time (30–90 min). The 24 full factorial CCRD design was applied, using four different parameters at five levels, each lead to 30 experiments to produce Pongamia pinnata oil-methyl esters (POMEs). The molar ratio of CH3OH to oil and RT were the most significant (p < 0.01) factors affecting the yield of POMEs. A linear relationship was recorded between the observed and predicted values (R2 = 0.9744). Using multiple regression analysis a quadratic polynomial equation was recognized for methyl ester yield (MEY). The quadratic term of CC showed a significant (p < 0.0001) impact on esters yield. The interaction terms of CH3OH to oil molar ratio and CC with reaction time exhibited a +ve effect on the MEY (p < 0.05). The optimum reaction conditions for trans-esterification of oils were 6.1 CH3OH to oil ratio, 1.0 % CC, 65 °C RT and 1:30 h reaction time, resulting in Pongamia oil MEY of 94.88 %. The RSM was found to be a suitable technique for optimizing trans-esterification process and produced fuel was within the ranges of ASTM D6751 and EN 14214 standards.