Study On Degradation Of 4-CP By Photocatalysis Combined With High-concentration Ozone Process And Its Synergistic Mechanism

Chlorophenol wastewater mainly comes from the petrochemical,coke,dyeing and weaving industries,with large emissions and high toxicity.Treating substandard chlorophenol wastewater will pollute aquatic organisms and cause pulmonary oedema and even death of surrounding residents.The current chlorophenol wastewater treatment process has the problems of limited degradation efficiency,low mineralization rate,and high energy consumption.This paper took p-chlorophenol as the research object,and used the photocatalysis combined with high-concentration ozone process to improve degradation performance.In medium-scale wastewater degradation experiments,the photocatalytic effect can stimulate high-concentration ozone to produce strong oxidizing particles,which effectively improves the degradation and mineralization rate of wastewater.The specific research contents are as follows:Build the gas circulation device to reduce exhaust gas emissions.Based on Computational Fluid Dynamics,the mass transfer process of ozone aeration in the reactor was studied.Combining the Two-film theory and Maxwell-Stefan theory to carry out numerical modelling of bubble mass transfer and molecular diffusion.Investigate the influence of mass transfer time,gas-liquid ratio,aeration area,bubble size and other factors on ozone concentration and gas-liquid mass transfer efficiency.According to the influence of the above factors,the mass transfer efficiency of the reactor was optimized.Gas-liquid mass transfer experiments were carried out to verify the accuracy of the model.Determine the appropriate range of mass transfer process parameters,and ensure that a high mass transfer efficiency can be obtained in subsequent degradation reaction.Use the photocatalysis combined with high-concentration ozone process to degrade medium-scale p-chlorobenzene wastewater.The degradation and mineralization capabilities under ozone concentration,Ti O₂ dosage,circulating gas volume and initial p H value were investigated,and the significance of each influencing factor was analyzed.A response surface regression model was established with the degradation time,catalyst dosage,and circulating gas volume as independent variables,and the influence of the factor on the degradation effect was analyzed.Use spectrophotometer and GC-MS to detect the trends and types of the initial products of the degradation process of p-chlorophenol,and establish the degradation route of p-chlorophenol under the O₃/Ti O₂/UV process.Determine the ozone water decay curve in O₃,O₃/UV,O₃/Ti O₂/UV to derive the ozone half-life to show the ability of ozone indirect oxidation in each system.The effects of different ozone concentration,UV intensity,and initial p H value on the yield of hydroxyl radicals in different systems were investigated,and the inhibitory effect of carbonate ions was analyzed experimentally.Hydroxyl radical quencher and hole scavenger were added to infer the main active particles of the photocatalysis combined with high-concentration ozone process,and to determine the synergistic mechanism of the degradation process.In this paper,ozone gas circulation degradation device was built to reduce exhaust gas emissions,the reactor was optimized for mass transfer based on the gas-liquid mass transfer numerical model and experimental results.Under certain technological parameters,the hydroxyl radicals and superoxide anion radicals excited by the system can effectively promote the degradation and deep mineralization of chlorophenol wastewater.The process parameters and mechanism analysis involved in the research can provide a certain reference for the subsequent industrial treatment of chlorophenol wastewater.