Photoelectrocatalytic Oxidation Degradation Of Organic Pollutants Containing Nitrogen

A large number of high-nitrogen organic pollutants directly entered the water body to form high-nitrogen organic wastewater,which makes it difficult to further reduce the total nitrogen of wastewater and increase the difficulty of sewage treatment.The subject uses photoelectric catalytic oxidation technology to degrade nitrogen-containing organic pollutants,with metronidazole as the target pollutant.The main research contents include:under the same reaction conditions,three oxidation treatment technologies of electrocatalytic oxidation,ultraviolet irradiation and photoelectric catalytic oxidation are used to degrade metronidazole simulated wastewater.Compared the effects of the three oxidation treatments on the degradation treatment of total nitrogen and metronidazole in simulated wastewater.Further,through a single factor oxidative degradation experiment,the effects of initial pH,initial concentration of pollutants,initial concentration of electrolyte,current density and reaction electrode spacing on the photocatalytic oxidation degradation of metronidazole simulated wastewater were investigated.The BBD response model is constructed by analysis to determine the interaction between the initial pH,the initial concentration of pollutants,the initial concentration of electrolytes and the current density,and the optimal analysis of the response surface model to obtain the primary and secondary relationships between the response factors and the best experimental results parameter.Finally,the experiment preliminary explored the reaction kinetics and mechanism of the reaction system of photoelectric catalytic oxidation degradation of nitrogen-containing organic pollutants in simulated wastewater,and speculated about the nitrogen conversion process.Through the experimental research and data analysis,the following conclusions are drawn:?1?For the degradation study of metronidazole simulated wastewater,under the same conditions,the photoelectric catalytic oxidation technology has the best treatment effect on metronidazole simulated wastewater,with a metronidazole removal rate of 99.21%and a total nitrogen removal rate of 48.09%.?2?Taking the initial pH,the initial concentration of pollutants,the initial concentration of electrolyte,the current density and the electrode spacing of the reaction system as the main factors affecting the reaction,a single factor reaction experiment was carried out on the photocatalytic oxidation degradation of metronidazole simulated wastewater.The best reaction parameters of various factors obtained from the experiment are initial pH=3,initial concentration of pollutants=50 mg/L,initial concentration of electrolyte=6 g/L,current density=20 mA/cm²,and electrode spacing=35 mm.?3?Through the response surface optimization experiment to explore the interaction between various factors and get the best reaction conditions of the experiment,under the initial pH=3,the initial concentration of pollutants is 50 mg/L,the initial concentration of electrolyte is 5.28 g/L,the current density is 20.66 mA/cm²,the electrode spacing=35 mm,the removal rate of metronidazole is the highest up to 99.6%;under the condition of initial pH=3,initial concentration of pollutants=25 mg/L,initial concentration of electrolyte=6.18 g/L,current density=20.81 mA/cm²,electrode spacing=35 mm,the total nitrogen removal rate can reach up to 51.7%.?4?The experiment explores the kinetic model of photoelectric catalytic oxidation degradation of nitrogen-containing organic pollutants,the mechanism of the reaction system and the process of nitrogen conversion.The results show that the photocatalytic oxidation process of degradation of nitrogen-containing pollutants fits well with the first-order kinetic model,and the chlorine radicals play a greater role in the removal of total nitrogen in simulated wastewater,When metronidazole is basically degraded,the nitrogen in the water mainly exists in the form of NO₃^--N,and the nitrogen concentration in various forms basically stabilizes.