Acetylene Black/manganese Dioxide Catalyzed Oxidation Of Organic Wastewater By Ozone Microbubbles

Ozone oxidation technology is widely used as an advanced oxidation technology because it does not causes secondary pollution.However,traditional ozone oxidation technology still has low ozone utilization and weak oxidizing power.Microbubble technology has attracted much attention as a method to effectively improve the gas-liquid mass transfer efficiency,and it can promote the generation of strong oxidant-hydroxyl radical?·OH?due to its different shrinkage and rupture characteristics compared with ordinary bubbles.At the same time,the addition of the catalyst can further increase the·OH production and significantly enhance the oxidation effect of the ozone oxidation technology.The main treatment object of this paper is the dye wastewater simulated by reactive brilliant red X-3B.The oxidation performance of ozone microbubble system,the synthesis and analysis of catalyst,the combined technology of microbubble and ozone catalytic oxidation system are studied.The details are as follows:?1?Ozone oxidation technology is combined with microbubble technology.The effects of bubble size,initial pH value,initial concentration of X-3B and ozone concentration on the oxidation performance of ozone microbubble system were discussed.The degradation process of X-3B in the system was preliminarily studied by free radical quenching experiment,UV and FTIR analysis.The results indicate that the oxidation capacity of the system is significantly enhanced after the bubble size is reduced from millimeters to micrometers or even nanometers.The ozone microbubble system has better oxidation performance under acidic conditions,increasing the ozone concentration or decreasing the concentration of X-3B can increase the oxidation rate.The better performance of microbubble ozonation treatment is achieved when the initial pH of the solution was 5,the initial concentration of X-3B was 100 mg·L^-1,and the ozone concentration was 5.52 mg·L^-1.Under these conditons,the decolorization efficiency reaches to 99.7%after treatment for 30 minutes.And the degradation process of X-3B followed the pseudo first order reaction kinetics.The free radical quenching experiment shows that·OH and O₂^-·are produced during the reaction,and O₂^-·is the main active substance.Infrared analysis showed that during the degradation process,the X-3B structure was destroyed to form a carboxylic acid or an ester species,so the pH of the solution decreased during the reaction.?2?The acetylene black/manganese dioxide?AB/MnO₂?catalyst was synthesized by mechanical stirring.The effects of the stirring time,loading ratio and calcination temperature on the activity of the catalyst were studied.The optimum preparation conditions of the catalyst were determined by comparing the effect of degradation of X-3B.And the catalyst was characterized by characterization.The results show that the catalyst has the highest catalytic activity when the stirring time was 5h,the loading ratio of acetylene black to manganese dioxide was 0.2g/6g and no calcination treatment.XRD characterization results show that the prepared MnO₂ is?-MnO₂.Combined with SEM analysis,it can be seen that acetylene black is embedded in the voids of MnO₂ to form a more loose porous agglomerate.The BET data showed that the specific surface area of the material increased after the reaction.XPS and FTIR data analysis showed that the material after the reaction still had good physical and chemical properties,which ensured the stability of the material.The free radical quenching experiment showed that·OH and O₂^-·were produced in the system,and O₂^-·had a great influence on the ozone oxidation effect.Compared with the ozone oxidation experiment,the addition of the catalyst not only promotes the production of·OH and O₂^-·in the ozone oxidation system,but also enhances the direct oxidation of ozone molecules.?3?Ozone catalytic oxidation technology combined with microbubble technology.By comparing the degradation rate of X-3B,the optimum dosage of the catalyst in the combined process and the optimum pH value of the reaction were determined.Based on the characteristics of the catalyst and microbubbles,the degradation process of X-3B was briefly analyzed.The research results show that the optimal dosage of the catalyst in the ozone microbubble catalytic oxidation system is 50 mg·L^-1.Under acidic conditions,the oxidation performance of the system is the best,the neutral is second,and the alkalinity is poor.The degradation process of X-3B followed the pseudo first order reaction kinetics.X-3B was degraded under the optimum reaction conditions of ozone microbubble system and ozone microbubble catalytic oxidation system.The results indicate that the X-3B decolorization rate increased from 33.1%to 68.6%after 5 min of reaction,which confirmed the strengthening effect of AB/MnO₂ catalyst on ozone oxidation ability.Finally,through the treatment of landfill leachate and turmeric saponin wastewater,it is verified that the system has a treatment effect on actual industrial wastewater,but the specific process conditions and degradation mechanism need to be further explored.