Kinetic insights into soybean peroxidase-catalyzed degradation of persistent organic pollutants

Abstract

Soybean peroxidase (SBP)-catalysed degradation of 2,4,6-trichlorophenol (TCP), triclosan (TCS), and bisphenol A (BPA) was investigated in batch systems as single-substrate and multi-substrate reaction media representative of industrial effluents. SBP was extracted from soybean hulls, reactions were carried out in the presence of hydrogen peroxide as co-substrate and substrate depletion was monitored by HPLC. The experimental results showed that pollutant interactions in mixed systems significantly affect degradation kinetics, revealing limitations of conventional single-substrate descriptions. To capture these effects, a modified bi–bi ping-pong kinetic model was formulated and fitted to the experimental data by computational parameter estimation. The proposed multiple-substrate model successfully described competitive effects and simultaneous pollutant removal. The estimated kinetic constants indicated no substantial variation in k₁, associated with the reaction between the enzyme and hydrogen peroxide, whereas all the substrate-dependent constants reflected the competitive effects arising from the simultaneous presence of the three pollutants. These results provide mechanistic and quantitative insight into SBP-catalysed oxidation under realistic conditions and support the use of SBP-based kinetic frameworks for process optimization, enzyme engineering, and scale-up of enzymatic wastewater treatment technologies.