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

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.