Chemical and Enzymatic transesterification of rubber seed oil – A comparative study

Abstract

Biodiesel produced from a wide variety of vegetable oils is expected to replace diesel fuel. Conventional diesel engines are the major sources of expelling the particulate matter, soot, smoke and oxides of nitrogen to the environment which are harmful. Biodiesel is an attractive alternative fuel to replace petroleum derived diesel because it is environment friendly and can be produced from edible or non-edible vegetable oils. The conflict between food and fuel led to the identification of more than fifty non-edible oil sources for biodiesel production. Utilization of locally available non-edible oil sources for production of biodiesel reduces the cost of fuel and increases production interest. Rubber seed oil is a non-edible type vegetable oil, identified as a potential feedstock for biodiesel production. This paper comprises the synthesis of biodiesel from high free fatty acid rubber seed oil through transesterification by chemical and enzymatic methods. The transesterification of rubber seed oil with chemical catalyst and enzyme catalyst were investigated in the work. The variables affecting the reaction such as molar ratio, catalyst concentration, time and temperature were analysed. Kinetic study was carried out to find the reaction constants and activation energy of both chemical and enzymatic transesterification reactions. The properties of fuel such as kinematic viscosity, calorific value and specific gravity were found out and compared with the properties of diesel. Base catalyst concentration was varied from 0.5wt% to 2wt% for alkaline transesterification process and the result revealed that maximum yield of 90% was obtained with a base catalyst concentration of 1.5wt% with 1:9 molar ratio at 55± 3°C. The best condition arise in enzymatic reaction was 10wt% enzyme and 1:4 methanol ratio with 5wt% addition of water as the solvent.