Study On The Catalytic Ozonation Of Phosphorus Containing Organic Compounds In Water Using Calcium Based Catalysts

With the development of human activities and phosphorus chemical industry,a large amount of phosphorus containing wastewater will be discharged.This includes inorganic phosphorus wastewater and organic phosphorus wastewater.Compared with inorganic phosphorus wastewater,organophosphorus wastewater has complex composition,high toxicity,and is difficult to degrade.Direct discharge will lead to eutrophication of water.Therefore,it is necessary to find a way to remove both organic matter and total phosphorus.In this paper,a calcium-based catalyst was prepared to catalyze ozonation of phosphorus containing organic matter,and the chemical properties,catalytic activity and catalytic mechanism of the catalyst were studied.In Part 1,Ca₂Mn₃O₈ catalyst was prepared by hydrothermal method to catalyze ozone degradation of glyphosate wastewater.Ca₂Mn₃O₈ was characterized by XRD,SEM,TEM,XPS and infrared to analyze the physical and chemical properties of the catalyst.After the catalyst was introduced into glyphosate wastewater,the p H of the solution increased slightly,and the COD removal rate reached more than 95%within 30 min,and the degradation effect was twice that of ozone treatment alone.The effect of different p H on COD removal was studied by adjusting the initial p H.Finally,more than 93%of the total phosphorus was removed by calcium ion precipitation.In Part 2,the initial concentration of glyphosate wastewater was increased and Ca Zr O₃catalyst was prepared by sol-gel method.The introduction of different dispersants in the preparation process will change the morphology and particle size of Ca Zr O₃,and also affect the catalytic activity.Ca Zr O₃ was characterized by XRD,SEM,TEM,XPS and infrared to study the physical and chemical properties of the catalyst and the changes of the catalyst before and after the reaction.The experimental results show that Ca Zr O₃-EG has better catalytic activity,which is attributed to its smaller particles,larger specific surface area and higher alkalinity.The conditions were optimized by adjusting catalyst dosage,substrate concentration,ozone flow and p H.Finally,the inorganic phosphorus was removed by introducing Ca²⁺.In the studies of the two Part,removal of COD and phosphorus requires two steps,and PO₄^3-,HPO₄^2-and H₂PO₄^-generated by the reaction can quench·OH in the reaction system,affecting the treatment effect.To solve this problem,Ca O catalyzed ozonation to degrade the wastewater with higher phosphorus content.In the Ca O/O₃ reaction system,the p H is significantly higher than that of the previous catalyst,and PO₄^3-,HPO₄^2-and H₂PO₄^-generated by the reaction will directly combine with Ca²⁺to form calcium salt precipitation.This not only facilitates the reaction,but also reduces the final dephosphorization steps in the first two chapters.Ca O acts as both catalyst and precipitator in the ozonation degradation of tetroxymethyl phosphorous sulfate wastewater,which achieves the purpose of simultaneously removing COD and total phosphorus.The conditions were optimized by adjusting catalyst dosage,substrate concentration,ozone flow and p H.At the end of the reaction,appropriate amount of CO₂ is injected into the wastewater to reduce the hardness of the wastewater.The experimental results show that the catalyst prepared in this project has a remarkable effect on catalytic ozonation and degradation of organic matter.In the process of organic degradation,organic phosphorus is oxidized to inorganic phosphorus and removed.The catalytic mechanism of the catalyst was studied,which provided a theoretical basis for the treatment of organophosphorus wastewater by catalytic ozonation.