Effective immobilization of laccase on TiO₂/g-C₃N₄ for enhanced chlorpyrifos degradation via photo-enzyme synergistic catalysis

Photocatalysis and enzyme catalysis are environmentally friendly technologies commonly used to degrade pollutants. However, single catalytic systems often exhibit insufficient catalytic performance, necessitating synergistic catalytic systems to enhance pollutant degradation. TiO₂ and g-C₃N₄ composite materials were used as carriers for laccase (Lac), and a photo-enzyme synergistic system was developed for chlorpyrifos (CPF) degradation. The prepared TiO₂/CN/Lac composite exhibited a large specific surface area (71.0809 m²/g) and a high enzyme activity recovery rate (83%). By adjusting the illumination conditions at the optimum pH of 3 and room temperature of 35 ℃, the composite material achieved a degradation efficiency of 74% for 20 mg/L of CPF within 24 minutes. Stability tests showed that after 5 cycles, the degradation efficiency only decreased by 11%. The degradation kinetics study of the composite material revealed a reaction rate constant (Kobs) of 0.0283 min⁻¹ for the photo-enzyme synergistic system, which was 1.7 times higher than that of the photocatalytic system and 7 times higher than that of the enzymatic system. As an environmentally friendly catalyst, TiO₂/CN/Lac has great potential in the degradation of CPF in the water.