Effective immobilization of laccase on high-dispersion mesoporous BiVO4/g-C3N4 microspheres for enhanced chlorpyrifos degradation via photo-enzyme synergistic catalysis

As environmentally friendly technologies, photocatalysis and enzymatic catalysis were commonly used for the degradation of pollutants. However, single catalytic system was limited in insufficient catalytic performance. So, synergistic catalytic system was required to facilitate pollutant degradation. Herein, the immobilized enzyme laccase (Lac) on highly dispersed BiVO4/g-C3N4 microspheres (BiVO4/g-C3N4/Lac) was prepared for photo-enzyme synergistic catalysis to promote chlorpyrifos degradation. The BiVO4/g-C3N4/Lac possesses an mesoporous structure with a large specific surface area (155.94 m(2)/g). The optimum immobilized enzyme activity could reach 560 U/g after laccase was immobilized of BiVO4/g-C3N4/Lac which was remarkably higher than that of free laccase. The efficiency of degradation of chlorpyrifos(CPF) of BiVO4/g-C3N4/Lac was as high as 78 % within 24 minutes. The reaction rate constant of BiVO4/g-C3N4/Lac was 0.0331 min(-1), which was 1.5 times that of the pure photo-catalytic system and 4 times that of the enzymatic system. Additionally, BiVO4/g-C3N4/Lac maintained a favourable stability with the degradation efficiency of approximately 68 % after five cycles. The reason for the enhanced performance of BiVO4/g-C3N4/Lac was that photo-enzymes cooperate to promote charge transfer. This work provides valuable insights on photo-enzyme synergistic catalysis for pollutant degradation.