MnO₂/Al₂O₃ Catalytic Ozone Microbubble Oxidation For The Advanced Treatment Of Coal Chemical Wastewater

Coal chemical wastewater is a typical refractory industrial wastewater,at home and abroad are generally used treatment of biochemical process.But the water still contains a large number of difficult to degrade toxic and harmful substances,mainly nitrogen heterocyclic,phenols and other substances.People want the water can meet the discharge standards by a certain depth of treatment,and also can reduce or get rid of toxic and hazardous substances of the water.Ozone can effectively remove the color,and can improve the biochemical characteristics.It has been applied to the treatment of modern industrial wastewater.In order to improve the efficiency of ozone oxidation to remove pollutants,ozone catalytic oxidation technology has become a hotspot in this field.In order to improve the efficiency of ozone utilization and removal of pollutants,on the one hand,it can study the development of high catalytic activity,long life,low cost and easy to industrial applications of the catalyst;on the other hand,it can combine with ozone microbubble technology.In this study,MnO₂/Al₂O₃ doped catalyst was prepared by doping method.The effects of the addition of MnO2,calcination temperature and calcination time on the activity of the catalyst were studied.The optimum preparation conditions of the catalyst were determined by comparing the effect of degradation of quinoline.And the catalyst was characterized by characterization.The results showed that the catalytic activity of the active component was the highest when the mass fraction of Mn O2 was 8%,the calcination temperature was 500 ? and the calcination time was 4h.From the XRD,SEM and BET methods,MnO2 was ?-MnO2,and the appearance was spherical with 30⁶0 nm.The specific surface area of the prepared MnO₂/Al₂O₃ catalyst is 183.22 m2·g-1 and the compressive strength is 31.84 N/grain.In this experiment,we found that when the influent quinoline concentration was 60 mg·L-1 and the reaction time was 90 min,the quinoline removal rate was above 95%,which was significantly higher than that of pure ozone microbubble oxidation removal rate of 48%.A non-homogeneous MnO₂/Al₂O₃ catalytic ozone microbubble oxidation system was established to treat a coal chemical wastewater.The optimum reaction conditions of the industrial wastewater were determined by examining the removal rate of TOC.The results show that the combination of ozone microbubble and doping MnO₂/Al₂O₃ catalyst has a good performance of oxidative degradation of organic compounds.The optimal reaction conditions of the system are: the optimal ozone dosage is 180 mg·h-1,the best hydraulic retention time is 10 min,the optimum initial pH is 9.0,the optimum dosage of the catalyst is 80 g·L-1.The COD and TOC of the effluent from the coal chemical wastewater were continuously monitored for 300 min.The COD and TOC of the effluent were basically stable after 30 min,the removal rate of TOC was about 56%,and the COD removal rate was about 65%.COD indicator is about 50 mg·L-1,there is a small fluctuation,the pH of the effluent is stable at about 8.5.COD of effluent meet the "Integrated Wastewater Discharge Standard"?GB8978-1996?level A standard,the system ozone utilization rate of 74%.The system has directive significance for the application of ozone catalytic oxidation technology in the practical treatment of industrial wastewater.