Study On Preparation And Application Of Fly Ash Supported Catalyst In Catalytic Ozone Oxidation Process

This study has prepared catalysts which based on fly ash loaded with metal oxide,andthe catalysts was applied to the catalytic ozonation process.Fly ash was a kind of solidwaste which was used to treat waste water,to achieve the purpose waste treat waste.Firstly,searching for the right modification methods of fly ash modification and thebest active component for preparation the best catalyst,determining the best condition ofpreparing catalysts with orthogonal test.Catalysts were characterised by BET and SEM forqualitative and quantitative analysis,and the adsorption performance of catalysts wasstudied.Secondly,catalysts were applied to treat actual wastewater in catalytic ozoneoxidation process,different factors were studied to determine the best experiment conditionof catalytic ozone oxidation.The last,study of catalytic ozone oxidation reaction kinetics,and probe into the reaction mechanism preliminaryly.Through the study of this thesis, the conclusions as follows:(1)Acid modified is one of the best modification methods of the fly ash.Experimentsshowed that the best active catalyst was MnO2/Fly ash.Prepared by orthogonalexperiment,the optimum conditions of preparation catalyst are:load capacity of2wt%,dipping time was20h, calcination temperature was400℃, calcination time was4h.MnO2has been dispersed on the surface of fly ash from photos taken by SEM,MnO2wasmeasured by energy spectrum accessory,before and after reaction,the mass fraction ofMnO2were18.80%and1.96%.(2) Fly ash loaded with MnO2was applied to catalytic ozone oxidation of printingand dyeing wastewater treatment.Prepared by single-factor experiments,the bestexperimental conditions are: O3volume fraction is40%of output (mass concentration is9.22mg/L), catalyst dosage is8g/L, pH is7.7, reaction time is60min. In this condition, theCOD removal rate from the separate ozone oxidation43.05%increased to75.07%.(3)Reaction kinetics was studied by try method,the level and two levels of equationswere fitted of the kinetics,it is found that catalytic ozone oxidation reaction were conformto the level.(4)Ozonation and catalytic ozonation system activation energy are15.17KJ/mol and25.45KJ/mol respectively which were measured by Arrhenius equation,the result showedthat the reaction activation energy required to reduce in the case of introducing catalyst,it isproved that catalysts play a catalytic role. (5)The application to spectrophotometric of ferroin was used to determine theapparent formation rate of·OH both in separate ozone oxidation and catalytic ozoneoxidation systems,the rate increased to0.225mmol/L from0.180mmol/L,it shows thatintroduction of catalyts promote ozone produces more·OH,and improve ability ofoxidation reaction system and ozone utilization.