Use of hydroxyapatite as a support in the immobilization of Thermomyces lanuginosus lipase for application in the production of biodiesel using a by-product as lipid raw material.

Abstract

The use of new materials in the field of biofuel production has been represented as a step in the development of remarkable catalysts. The use of lipases in the production of biodiesel is often seen as a cost-limiting step, as the operating expenses in recovering such catalysts can lead to unfeasible market expectations. In this study, hydroxyapatite (HAp) particles were evaluated as a support to immobilize commercial lipase, following application in ethyl ester synthesis. First, hydroxyapatite was synthesized through the co-precipitation method at constant pH and selected as a support to be used in enzyme immobilization. The characterization of the biocatalyst support materials produced was carried out using DRX, BET, FTIR, TGA, and SEM analysis. The lipase from Thermomyces lanuginosus was then immobilized in the matrices, and, subsequently, there was transesterification of the vegetable oil deodorization distillate (VODD). The biodiesel samples generated showed that they were within commercial standards, achieving ester conversion greater than 96.5%. Other properties such as density (0.87 g.cm-3) and viscosity (4.36 mm2.s-1) meet the specifications required by ASTM to be used as a biofuel. In the experiment planning technique, the results revealed an experimental trend and a defined behavior: a higher lipase loading in the immobilization and the use of temperatures in the range of 40-50 °C favor high conversions of ethyl esters. Thus, this confirms that the enzymatic chemical catalyst was able to form the main fatty acid esters even using a residual lipid raw material.