Study On The Dye Wastewater Treatment By Fenton System And Iron Recycling And Resource Utilization

Fenton oxidation technology which has high efficiency and complete oxidation degradation,is an efficient technology for dye wastewater treatment.However,a lot of iron sludge is inevitably generated during homogeneous Fenton treatment process,which not only increases the cost of sludge treatment,but also causes the waste of iron resources.Therefore,how to avoid the formation of iron mud and the recycling of iron resources has become the key to solve this problem.In this thesis,the representative cationic and anionic dye crystal violet and acid fuchsin were selected,and two kinds of simulated dye wastewater were treated by Fenton oxidation technology.Through single factor and orthogonal experiments,the effects of H₂O₂ addition,Fe SO4 addition,initial dye concentration,p H and salinity on decolorization rate were investigated.Meanwhile,the degradation kinetics of dye wastewater was studied.On the basis of optimal reaction conditions,the dyestuff wastewater after degradation is used as the iron source to prepare iron phosphate by external phosphorus source.The effects of reaction temperature and time,high molar ratio,p H and other factors on the synthesis,analysis and characterization of the synthesized product by TG-DSC,XRD,SEM-EDX,FTIR etc..The main results are as follows:?1?The single factor and orthogonal test of dye wastewater degradation showed that when the initial wastewater concentration was 500mg/L,the dosage of Fe SO4 was 0.34 g,the dosage of H₂O₂ was 0.30 m L,the p H was 4,the temperature was 35?,Salinity 4g/L,the reaction time of 60 mins,the decolorization rate of dye wastewater up to 99.4%.For the acid magenta dye wastewater,the decolorization rate was as high as 99.2% when the initial concentration of wastewater was 800 mg/L,the amount of Fe SO4 was 0.14 g,the amount of H₂O₂ was 0.25 m L,the p H was 2,the temperature was 35? the reaction time was 30 mins and the salinity was 4 g/L.For the crystal violet dye wastewater,the decolorization rate of the order is: reaction temperature> reaction time> Fe SO4 dosage> initial concentration of wastewater> H₂O₂ dosage> p H> salinity.For the acid magenta dye wastewater,the order of the decolorization rate is as follows,Fe SO4 dosage?reaction temperature,reaction time?> salinity > p H > initial wastewater concentration?H₂O₂ dosage?.?2?Degradation kinetics of dye wastewater showed that the R2 of first-order and second-order kinetics curves of crystal violet were 0.983-0.9938 and 0.9966-0.9992,which is more consistent with the second order reaction kinetics.The first order kinetics of acidic magenta degradation and the second order The R2 of the kinetic fitting curve are 0.9942 and 0.9922,which is more consistent with the first order reaction kinetics.?3?The single factor experimental study on iron resource recovery showed that the best performance of the prepared iron phosphate crystals was obtained at p H 1.5,reaction time 0.5 h,reaction temperature 25? and molar ratio of iron phosphate to iron 1:1.TG-DSC analysis showed that the initial synthesized iron phosphate product contained two crystals of water,Fe PO4·2H₂O.After calcination at high temperature,XRD and SEM-EDX analysis showed that the crystallization performance of iron phosphate was improved.The morphology was elliptic rod-like and disciform layered structure.