A KINETIC STUDY ON ACID CATALYZED ESTERIFICATION OF FREE FATTY ACIDS IN RICINUS COMMUNIS OIL FOR THE PRODUCTION OF BIODIESEL

Abstract

The world economy is presently confronting an era of energy crisis as it primarily depends upon the conventional energy resources for meeting its demand that accounts for 80% of the energy expenditure[1]. Gradual depletion of conventional fossil fuel reserves, ambiguous fluctuations in its prices and the ever-increasing greenhouse gas emissions have intensified research on the scope for renewable fuels from alternative feedstocks towards mitigation of acute energy crisis. Recently biodiesel has withdrawn eminent interest as a vehicular fuel as it can be synthesized from a large variety of raw materials[2]. The present investigation emphasizes the optimization of acid esterification of non-edible castor (Ricinus communis) oil towards preparation of biodiesel under the influence of four process parameters viz. reaction time (0 to 4 h), reaction temperature (40 to 80 0 C), catalyst concentration (0.25 to 3.25 w/w) and molar ratio of methanol to oil (1:1 to 20:1). The effect of each parameter on the conversion of fatty acids into FAME has been discussed. Optimal conditions during which the FFA was reduced from 4.038 to 1.076 % were: 1 % w/w conc. H2SO4, 15:1 molar ratio of methanol to oil, reaction temperature 50 0 C and reaction time 2.09 h. Among all the process variables, reaction temperature exhibited the most significant effect. Kinetic study of the optimized process parameters was performed. The experimental results were found to fit pseudo first order kinetics. These results were further fitted into the Arrhenius equation to determine the effect of temperature on rate constants. Activation energy and frequency factor were estimated as 22.148 KJ/mol and A = 2.710 min -1 respectively.