Eriochrome Blue Black R and Fluorescein degradation by hydrogen peroxide oxidation with horseradish peroxidase and hematin as biocatalysts

We describe an UV–vis study of Eriochrome Blue Black R and Fluorescein elimination by chemical transformation and oligo/polymerization using the horseradish peroxidase enzyme (HRP) and the biomimetic hematin as catalysts in aqueous solution. Using HRP/H2O2 and Eriochrome Blue Black R a decolorization of 92.5% was achieved at the highest dye concentration (150 mg/L). In the case of the hematin/H2O2 system, the decolorization of Eriochrome Blue Black R solutions decreased with the increase of the dye concentration reaching only a removal of 30.2% at the highest dye concentration tested. Fluorescein decolorization in the presence of HRP was very good at 25 mg/L (near 85%) but decreased to 35.7% as the dye concentration increased to 150 mg/L. On the other hand, hematin was poorly active as catalyst for Fluorescein elimination. The use of hematin as catalyst instead of HRP has advantages from the technological and economical points of view for Eriochrome Blue Black R. Hematin can be considered an adequate alternative to the use of enzymatic catalysts based on peroxidases.