Phenol‐mediated decolorization and removal of disperse dyes by bitter gourd (Momordica charantia) peroxidase

Abstract

Salt‐fractionated bitter gourd (Momordica charantia) proteins were employed for the decolorization of disperse dyes in the presence of H₂O₂. The effect of various experimental conditions such as concentration of enzyme, H₂O_2, phenol, reaction time, pH and temperature on the decolorization of dyes was investigated. Dyes were recalcitrant to the decolorization catalysed by bitter gourd peroxidase. However, these dyes were decolorized significantly in the presence of a redox mediator, phenol. Bitter gourd peroxidase (0.215 U/mL) could decolorize about 60% of Disperse Red 17 in the presence of 0.2 mM phenol, whereas Disperse Brown 1 was decolorized by only 40% even in the presence of 0.4 mM phenol. Maximum decolorization of dyes was achieved in the presence of 0.75 mM H₂O₂ in a buffer of pH 3.0 and 40 °C within 30 min. The K_m values obtained were 0.625 mg/(L·h) and 2.5 mg/(L·h) for Disperse Red 17 and Disperse Brown 1, respectively. In all the experiments, Disperse Brown 1 was found to be more recalcitrant to decolorization catalysed by bitter gourd peroxidise, as compared to Disperse Red 17.

Keywords:

• decolorization
• disperse dyes
• Momordica charantia
• peroxidase
• phenol

Acknowledgements

Aligarh Muslim University is gratefully acknowledged for providing a University Grants Commission (New Delhi) sponsored fellowship to Rukhsana Satar.