Multi-response and multi-criteria decision-making optimization of transesterification reaction for biodiesel production based on critic weight determination method

Abstract

Population, industrialization, and urbanization made to exploit high volume of fossil fuels such as diesel to meet energy demands. Excess application of fossil fuels created environmental and health threats, hike in oil prices, and depletion of resources. Biodiesel was termed as a predominant alternative renewable fuel for diesel engines. In this research, a novel fuel is produced from the mixed feedstocks such as castor oil, mahua oil, and processed dairy waste by mixing in equal volumes (each 33.33% v/v). An esterification reaction was performed initially, since the acid value of raw oil is found to be 4.11 mg KOH/g oil. Three different acid catalyst concentrations (1, 2, and 3% v/v) were used to ascertain the effect of acid catalyst concentration on the acid value of oil. The acid value of esterified oil from the esterification reaction tends to decrease with an increase in acid concentration. Transesterification reaction parameters such as catalyst utilization (wt%), reaction temperature (°C), and oil to methanol ratio (molar) were varied in three levels (27 transesterification experiments) based on the Taguchi method to find the optimal reaction parameters for maximum biodiesel yield, high fuel flash point, and low fuel viscosity. At the end of each transesterification reaction, biodiesel yield percentage, and its properties such as fuel flash point and viscosity were measured as per the ASTM standard (D6751). Based on the multi-criteria decision-making-GRA method, the optimal value for maximum biodiesel yield and fuel properties such as flash point and viscosity was determined as catalyst utilization (3 wt%), reaction temperature (55 °C), and a molar oil to methanol ratio of 12. In addition, an earthen lamp test was conducted and measured properties of fuel were delineated to reveal that the produced biodiesel from the mixed non-edible oil is an effective feedstock for biodiesel production.