Esterification of Free Fatty Acids in Waste Oil Using a Carbon-based Solid Acid Catalyst

Catalyst plays an important role in the production of biodiesel from waste oils. Heterogeneous catalysts are gaining importance owing to the advantages in terms of separation and reusability over the traditionally used homogeneous catalyst. Catalyst from renewable sources such as biomass has been introduced to make the process fully 'green'. The carbon based materials are considered as ideal catalysts due to desirable features such as low material cost, high surface area and thermal stability. In the present work, a strong solid acid catalyst, prepared by sulfonating carbonized rice husk, was proved to be an efficient and environmental friendly catalyst for the esterification of waste cooking oil and methanol. The effect of various parameters like catalyst concentration, oil to methanol molar ratio, stirring speed and temperature were studied for the free fatty acid conversion of waste oil having acid value of 28 mg KOH/gm of oil.