Immobilization of horseradish peroxidase in Ca-alginate beads: evaluation of the enzyme leakage on the overall removal of an azo-dye and mathematical modelling.

MORALES URREA, DIEGO ALBERTO; FERNÁNDEZ GIMENEZ, ANALIA VERÓNICA; RODRIGUEZ, YAMILA ELIANA; CONTRERAS EDGARDO MARTÍN

PROCESS SAFETY AND ENVIRONMENTAL PROTECTION

INST CHEMICAL ENGINEERS

Año: 2021 vol. 156 p. 134 - 143

0957-5820

Horseradish peroxidase (HRP) was immobilized in calcium alginate beads by extruding an alginate/HRPsolution through a syringe onto calcium chloride. The aim of this study was to evaluate their use to removethe azo-dye Orange II (OII), under different experimental conditions, such as the number of beads, pH, reuseof the biocatalyst, hydrogen peroxide feeding strategy. A mathematical model that takes into account thediffusion of reactants, products, and HRP throughout the beads and the effect of the enzyme leakage on theobservable oxidation rate was also developed. Results indicated that the immobilization efficiency decreased as a function of the incubation time in CaCl2. Although enzyme-containing beads had a low OIIadsorption capacity, under the presence of hydrogen peroxide, the dye removal was highly increased due tothe catalytic activity of HRP. Besides, the initial OII oxidation rate (RS0) using 3 beads at pH 9 was higherthan at pH 7. Also, RS0 increased as a function of the number of tested beads. The developed model wasfitted to experimental data obtained at different conditions. Then, the model was validated against a newdata set that was not used for the calibration of the model, obtaining a satisfactory agreement betweensimulation results and these new data. Simulations demonstrate that 70?90% of the total OII removed wasdue to its oxidation by hydrogen peroxide catalyzed by HRP in the liquid phase