Comparative study of alcohol blends on biocatalyzed hydrolysis and transesterification of cottonseed oil

Abstract

The need to search for alternative sources of energy which are safe, renewable and non-polluting has gained highest priority across the globe due to uncertain supplies and high price hikes in fossil fuels. One of the promising alternatives is Biodiesel, a renewable fuel which can be defined as methyl or ethyl ester of fatty acid made from vegetable oils (both edible and non-edible) or animal fat. The present study outlines the observations on the fatty acid alkyl ester generation by transesterification reaction of cottonseed oil using Aspergillus species as whole-cell biocatalysts. Work also represents difference in ester yield on addition of alcohol blends with two different molar ratio (1:4 or 1:6). No significant difference was observed in transesterification ester yield with both the molar ratio of alcohols. The transesterification of cottonseed oil yielded 91% and 87% of alkyl esters using molar ratio 1:4 and and 1:6 molar ratio (oil to alcohol) respectively. As per ASTM 6751 the properties like density, viscosity, gross calorific value, flash point, cloud point and pour point for accessing the fuel quality of cottonseed oil ethyl-butyl and ethyl-propyl blend ester showed significant similarities with petroleum based diesel. The study thus demonstrates the use of whole cell as biocatalyst for transesterification of cottonseed oil to alkyl ester can be potentially used as biodiesel.