Effect of organic solvents and cosolvents on lipase-catalyzed transesterification of canola oil

In this thesis, the effect of organic solvents and cosolvents on enzymatic transesterification of canola oil by Candida antarctica lipase was investigated. Twenty-eight organic solvents were assessed and hydrophobic iso-octane was found to be the ideal solvent. Relatively high product yields were also obtained with several hydrophilic solvents possessing high miscibility with methanol. Various solvent-cosolvent mixtures were established to enhance both enzyme activity and mass transfer of substrates. Each mixture comprised a hydrophobic solvent and a hydrophilic cosolvent. At low cosolvent concentrations, biodiesel yield may be enhanced due to improvement in the dispersion of methanol in the cosolvent media. However, at higher cosolvent concentrations, biodiesel yield was reduced due to inactivation of lipase. Solvent parameters such as log P, dielectric constant, and Hildebrand solubility parameter, were correlated with biodiesel yields to explore their potential relationship to enzyme activity. The effect of water content on lipase activity was also ascertained.