Optimization of hydrolysis of acid oils catalyzed by immobilized lipases

Abstract

Biodiesel is traditionally produced by homogeneous basic catalysis, which requires refined oils with low acidity in order to avoid saponification reactions. Refined oils account for a large amount (70-80%) of the total cost for biodiesel production. Therefore, inedible oils of low quality (oils with high content of free acids) could contribute to the reduction of the costs of production of this biofuel. These oils can be used in the production of biodiesel by heterogeneous enzymatic catalysis, which can contribute to the reduction of costs with raw material, energy demand of the plant and processes of purification of biodiesel and glycerol and treatment of effluents. Lipases are promising enzymes in the production of biodiesel by hydroesterification, a process involving two steps: (I) hydrolysis of vegetable oils producing an aqueous phase (water, glycerol and enzyme) and an organic phase (free fatty acids - FFA); (II) esterification of the AGL with ethanol producing ethyl esters of fatty acids (biodiesel). Hydroesterification has the advantages of producing glycerol (first step) and biodiesel (second step) with high purity. The glycerol produced in the first step using a salt-free oil/water emulsion can be considered as food grade and it can be used in food, cosmetic and pharmaceutical industries. As an alternative proposal to the production of biodiesel by transesterification, we intend to evaluate immobilized lipases in the hydrolysis of acid oils with recycle of the heavy phase (water, glycerol and biocatalyst) to concentrate the aqueous glycerol solution.