Oxidative degradation and detoxification of textile azo dye by horseradish peroxidase enzyme

Horseradish peroxidase (HRP) can be readily extracted
from horseradish roots. In this research, the application of
acid blue-25 (AB-25) dye removal by low purity horseradish
peroxidase extracted from horseradish root (crude
HRP) was investigated. Parameters, such as amount of HRP,
contact time, pH, H2O2 concentration, AB-25 concentration
and temperature during enzyme-mediated dye degradation
and detoxification, were studied. Results showed that decolorization
of AB-25 at 75 min contact time, pH 7and
0.8 mM/L H2O2 for 1 U/ml crude and pure HRP were
approximately 80 and 94%, respectively. Also, gradually
adding of H2O2 and enzyme increased the turnover of the
HRP compared to control. Polyethylene glycol (PEG) in
various concentrations did not significantly affect the reduction
of HRP inactivation. Toxicity test with Daphnia
magna showed a reduction in toxicity after the enzymatic
treatment. To meet the optimized conditions in the process,
the ratios of dye/ enzyme and H2O2/dye, and sequences of
the addition of reactants, should be considered