Experimental Study On Ozone Catalytic Oxidation Of Organic Wastewater

The high-concentration of organic wastewater is produced in the chemical production.The components of wastewater are complex.It is difficult to be biodegraded and treated.At present,the common method for high-concentration organic wastewater is physicochemical method by using iron-carbon micro-electrolysis and Fenton oxidation,which has the problems of low processing efficiency and much sludge.The sludge belong to hazardous wastes,which need to speed much money to conduct.Compared with traditional physicochemical treatment,catalytic-oxidation technology has obvious advantages and smaller sludge generation.It is used in more wastewater treatment,which has become a research hotspot in recent years for the chemical treatment of high-concentration organic wastewater in chemical industry.The research focus of ozone catalytic oxidation technology is embodied in the development of catalytic oxidation catalyst and the optimization of ozone catalytic oxidation process parameters.The choice of catalyst is currently focused on the development of metal catalysts.The optimization of process parameters is mainly reflected in how to improve the efficiency of ozone utilization.The thesis mainly uses surface-treated copper-containing sludge produced by circuit board manufacturing enterprises as raw materials to prepare metal catalysts.Copper-containing sludge is belong to hazardous solid waste.It is necessary to entrust qualified units for harmless disposal.Rich in copper and other metals,it can meet the conditions of ozone catalytic oxidation,which can reduce the preparation cost of the catalyst.This method utilize the waste resources,which has certain environmental and economic benefits.The thesis mainly prepared two kinds of metal catalysts,one used copper-containing sludge to burn copper catalyst directly,and the other used copper-containing sludge as carrier to prepare Fe₂O₃-TiO₂-Mn O₂-Cu O composite catalyst.Ozone catalytic oxidation of high-concentration organic wastewater by self-made catalyst which the target pollutant is toluene.The effect of process conditions on ozone catalytic oxidation of organic wastewater was studied,and compared with commercial catalysts.Finally,the kinetics and mechanism of ozone-catalyzed oxidation in organic wastewater are analyzed through experiments.Concluded as follow:（1）In the homogeneous catalytic oxidation system,using copper-containing sludge as a catalyst to conduct the catalytic ozone oxidation research on the organic wastewater.The experimental results show that the main components of copper-containing sludge are calcium carbonate and copper ions.When the catalyst dosage is 2g/250m L and the intake ozone concentration is 1L/min,the efficiency of toluene in ozone oxidation wastewater reaches a maximum of 73.1%.（2）In the heterogeneous catalytic oxidation system,Fe₂O₃-TiO₂-Mn O₂-Cu O composite catalyst was prepared by the impregnation method.Based on the removal efficiency of toluene in ozone-oxidized organic wastewater,the preparation conditions and process conditions were optimized.The experimental results show that the active components of Fe₂O₃,TiO₂,Mn O₂ have been successfully loaded on the surface of copper-containing sludge,and the basic structure has not changed through characterization analysis.The best catalyst preparation conditions are determined by single factor experiment.Ti⁴⁺,Mn²⁺and Fe³⁺molar ratio is 2:2:1,the optimal calcination temperature is 500℃,and the calcination time is 2h.The best process conditions are determined by single factor experiment.The catalyst dosage is 2g/250m L,and the ozone concentration in the intake air is 1L/min.Under the best preparation conditions and process conditions,the removal efficiency of toluene in ozone catalytic oxidation organic wastewater reached 88.87%.（3）The comparison experiment of toluene in ozone-catalyzed oxidation by self-made catalysts and commercial catalysts（activated carbon,honeycomb ceramics）.The experimental results show that the ozone catalytic oxidation efficiency of activated carbon in the first 15minutes is 54.78%,the ozone catalytic oxidation efficiency of honeycomb ceramics is 69.96%.The ozone catalytic oxidation efficiency of copper-containing sludge is 71.82%.The copper catalyst ozone catalytic oxidation efficiency was 77.12%,and the Fe₂O₃-TiO₂-Mn O₂-Cu O composite catalyst ozone catalytic oxidation efficiency was 88.87%.The self-made catalyst ozone catalytic oxidation efficiency is significantly higher than the commercially available catalyst.（4）When the number of aeration stages is two,the efficiency of toluene in ozone catalytic oxidation of organic wastewater is the highest,the removal efficiency of copper catalyst is 46.7%,and the removal efficiency of Fe₂O₃-TiO₂-Mn O₂-Cu O composite catalyst is 54.31%.（5）Through kinetic analysis,separate ozone oxidation and ozone catalytic oxidation of toluene in organic wastewater are conformed to the quasi-first-order reaction kinetic model.The higher the toluene concentration in the organic wastewater,the higher the ozone oxidation efficiency.From the analysis of reaction rate,the catalytic oxidation rate of ozone is significantly higher than that of ozone oxidation.The ozone oxidation rate constant is 0.02min^-1.The copper catalyst ozone catalytic oxidation rate constant is 0.0395min^-1,and the Fe₂O₃-TiO₂-Mn O₂-Cu O composite catalyst ozone catalytic oxidation rate constant is 0.0607min^-1.The mechanism of ozone oxidation was analyzed by tert-butanol as a trapping agent.Both ozone oxidation and ozone catalytic oxidation followed the hydroxyl radical mechanism.