Modified Graphite Phase Carbon Nitride Photocatalysis And Synergistic Sodium Percarbonate Degradation Of Methylene Blue

Drainage of printing and dyeing wastewater is large,and it is one of the most important water pollution.The environmental problems caused by the discharge of untreated printing and dyeing wastewater need to be solved urgently.This paper mainly focuses on the experimental study on the degradation of printing and dyeing wastewater by graphite phase carbon nitride modification and sodium percarbonate,with methylene blue（MB）as the target pollutant.The specific research content is as follows:1.Phosphorus-doped graphite-phase carbon nitride nanosheets（PS-CN）were prepared by thermal polycondensation method and thermal stripping method using urea as a precursor and hydrogen diamine phosphate as a phosphorus source.Scanning electron microscope（SEM）,X-ray diffraction（XRD）characterizes the surface and structure of the sample.MB was degraded by PS-CN under simulated sunlight conditions.The effects of catalyst dosage,thermal stripping time,solution p H,reaction temperature,and reaction time on MB degradation were investigated.When the MB concentration was30 mg/L and the PS-CN dosage was 1.0 g/L,the reaction was conducted for 60minutes,and the MB degradation rate was 92.4%.2.Using melamine as a precursor,graphite phase carbon nitride was prepared by thermal polycondensation,and the surface and structure of the samples were characterized by scanning electron microscope（SEM）and X-ray diffraction（XRD）.MB was degraded with g-C₃N₄ in combination with sodium percarbonate（SPC）.The effects of the conditions such as SPC dosage,g-C₃N₄ dosage,reaction temperature,initial p H of the solution,and reaction time on MB degradation were investigated.When the MB concentration was 10 mg/L and the amount of g-C₃N₄ was 1.0 g/L,the reaction was performed for 90 minutes,and the MB degradation rate was 97.7%.3.Phosphorus-doped graphite phase carbon nitride（P-CN）was prepared by thermal polycondensation using melamine as the precursor and hydrogen diamine phosphate as the phosphorus source.MB was degraded with P-CN and sodium percarbonate（SPC）.The effects of SPC dosage,P-CN dosage,reaction temperature,initial p H of solution,and reaction time on MB degradation were investigated.When the MB concentration was 10mg/L and the amount of P-CN was 0.75 g/L,the reaction was conducted for 60minutes,and the MB degradation rate was 99.7%.In this paper,melamine is used as a precursor to prepare phosphorus-doped graphite phase carbon nitride,which cooperates with sodium percarbonate to degrade printing and dyeing wastewater.Through a simple g-C₃N₄ doping method,the reaction time is shortened and the MB degradation rate is improved.There is a large application space in wastewater treatment.