Abstract
The use of enzymatic route for production of biofuels is growing up due the mild reaction conditions that this method provides, as well as reducing SOx emission. To reduce costs, it’s necessary to immobilize the enzyme, making possible to use it continuously as biocatalyst. The aim of this work was to measure the influence of the mass of support and pH used for immobilization of commercial lipase from Candida rugosa acquired by Sigma laboratory. The immobilization method chosen was adsorption on mesoporous and hydrophobic support MCM 41, this has been treated with nitric acid 10 % v/v to remove any organic residue. Then, 20 mL of enzymatic solution in phosphate buffer (pH 6.0, 7.0 and 8.0; 50mM) and 1 g/L was placed under constant stirring with 0.30 and 0.45 g of support. Aliquots were taken from the reaction medium and analyzed by spectrophotometry at 10 min intervals. A volume of 0.2 mL of supernatant was put with 1.8 mL of substrate p-NFL at 0.18 g/L, and the absorbance at 410 nm was analyzed. In four cases there was a sharp reduction of supernatant’s activity at first 10 min, that ratifies the big affinity of the enzyme for the support and the negative influence of pH about the activity. Using the calibration curve, it was possible to calculate the final activity of each immobilization batch. This work suggests the occurrence of diffusional effects, which means that the enzyme mobility was restricted due the excessive amount of support, and then, it lost a part of accessibility to substrate, reflecting in not expressive activity values, and changing the state of ionization of the components of the system.
