Controllable Construction Of Photo-enzyme Coupled Artificial Catalytic System Based On Carbon Nitride And Study Of Phenolic Pollutants Degradation Performance

Industrial production had flourished with the advancement of science and technology,however,the water pollution it has brought were the biggest obstacles restricting the people of our country to move toward green development.It is the scientific research barrier,looking for a green,environmentally friendly,low energy consumption and recyclable wastewater treatment technology,that need to be broken through.Photocatalytic technology stands out among many strategic technologies by virtue of its advantages of using solar energy to solve water pollution.Graphite phase carbon nitride?g-C₃N₄?was a new type of non-metallic semiconductor photocatalytic material with excellent photoelectrochemical properties,good stability,excellent biocompatibility,and has become a popular material in the field of photocatalysis.However,the higher carrier recombination rate of g-C₃N₄ seriously restricts its development in the field of photocatalysis.In order to improve the photocatalytic performance of g-C₃N₄,in this paper,horseradish peroxidase?HRP?is used as an auxiliary agent,and g-C₃N₄ with different morphologies as the main catalyst to prepare a photo-enzyme coupled artificial catalytic system.Through a series of tests,the composition,structure,morphology,physical and chemical properties and performance of the composite catalyst were obtained:?1?By molecular doping,p-benzoquinone and milleramine were mixed and heat-condensed to prepare MABQ with better performance.Through the method of metal ion bridging,HRP was immobilized on the surface of MABQ to form MABQ/HRP photo-enzyme coupled artificial catalytic system.The degradation rate of BPA by the composite catalyst was 92.22%in 60 min.The degradation rate of 0.0427 min^-1 was2.47,7.78 and 81.02 times of MABQ-1(0.0173 min^-1),g-C₃N₄(0.00549 min^-1)and HRP(0.000527 min^-1),respectively.After the cycle,the degradation rate remained above 85%,indicating the high efficiency and stability of the photo-enzyme coupled artificial catalytic system.The corresponding values of the transient photocurrent of MABQ/HRP were 3.5 and 7 times that of MABQ and g-C₃N₄.The experimental results showed that the solid-loaded HRP greatly improved the carrier mobility and separation efficiency,and further enhanced the photocatalytic activity of MABQ/HRP.?2?The HRP was immobilized on the surface of mesoporous g-C₃N₄?MCN?,prepared by the bubble template method,via dropwise stirring to prepare the MCN/HRP photo-enzyme coupled artificial catalytic system.The staggered pore structure increased the specific surface area of the catalyst and provided more loading sites for HRP.The performance test showed that the degradation rate of BPA by MCN/HRP is85.7%in 50 min,much higher than MCN?48.2%?and HRP?2.7%?.There was little change with the performance of the photo-enzyme composite catalyst over different temperatures and pH.The degradation rate and relative enzyme activity after cycling were maintained at about 80%,indicating that the catalysts had excellent degradation ability,cycle stability and environmental tolerance.Utilizing the photogenerated electrons and H₂O₂ generated by MCN further improved the photocatalytic performance.?3?HRP was immobilized into the interior of hollow spherical g-C₃N₄?HCN?through pores on the surface,and the HRP@HCN nanoreactor with enrichment effect,high-frequency collision effect,and light reflection/refraction effect was prepared.The degradation rate of BPA in the nanoreactor reached 94.98%within 60 min,and the degradation rate was 0.0473 min^-1,which was much higher than that of HCN.The HRP inside the catalyst made full use of photogenerated electrons and H₂O₂,which improved the electron and oxygen transfer rate and further improved the photocatalytic performance.The degradation rate of the photo-enzyme composite catalyst was maintained at about 90%at different temperatures?0-60??and pH?3-8?,and the degradation rate and relative enzyme activity after cycling was maintained at around85%,indicating the nano-reactor had excellent degradation ability,cycle stability and environmental tolerance,which may meet the requirements of industrial use.