Study On The Degradation Of Wastewater And Mechanism Research Of Modified Fenton-like System

As a green advanced oxidation technology,Fenton method produces high oxidizing agent hydroxyl radical?·OH?,who owns a high oxidation potential of 2.8 eV to efficiently oxidize organic matter in water.It has a wide application prospect in the field of water environmental pollution control.The Fenton method has the advantages of non-toxic reagent,high oxidation efficiency and simple operation.However,the low yield of hydrogen peroxide?H₂O₂?,demand of narrow pH range and the need for casting iron ions have restricted the development of the Fenton method in advanced oxidation field.In order to improve the efficiency of organic printing and dyeing wastewater's degradation,a series of experiments have made through applying new electrolytes,modified cathode materials and modified photocatalyst in Fenton like systems.This topic is aimed at solving the existing problems in Fenton like method.The main research contents of this experiment include the following aspects.?1?Sodium tripolyphosphate?STPP?/electro-Fenton?EF?In this experiment,a modified electro-Fenton?EF?system was formed with sodium tripolyphosphate?STPP?was used as electrolyte,iron plate as anode,carbon fiber felt as cathode.Methylene blue was used as a pollutant.After an hour of degradation,nearly 96%of methylene blue was removed in STPP/EF.Sodium sulfate?Na₂SO₄?and ethylenediamine tetra acetate?EDTA?were used as comparison electrolytes respectively.The degradation rate of STPP/EF was 1.7 times as much as Na₂SO₄/EF,1.2 times of EDTA/EF.The optimum pH of the modified Fenton system was 6,and it also had good degradation ability in the range of pH4-10.The hydrogen peroxide accumulation amount in the STPP/EF system was 4.2 mg/L within one hour.While the amounts of hydrogen peroxide accumulation in EDTA/EF was 6.4mg/L,and Na₂SO₄/EF was 1.7 mg/L.Through the study of double cells STPP/EF,it was found that both cell in EF can produce hydrogen peroxide.After an hour,the cumulative amount of hydrogen peroxide was 5.4 mg/L in the cathode chamber and 3.9 mg/L in the anode chamber.?2?Iron and nitrogen doped graphene aerogel?FNGA?/electro-Fenton?EF?In this experiment,a modified electro-Fenton?EF?system was formed with sodium sulfate as an electrolyte,platinum plate as an anode and FNGA as the cathode.FNGA was prepared by hydrothermal method.The characterization results show that FNGA has good morphology and structure.Rhodamine B was applied as pollutant,after one hour of degradation,the degradation rate was 97.6%in FNGA/EF,which exceeded 3.6%of graphene aerogel as cathode material,exceeding 8.8%of using carbon plate.The removal rate of COD in FNGA/EF reached to 88.63%after one hour,which exceeded 13%of graphene aerogels.And the energy consumption is lowest when using FNGA as cathode.The removal rate of rhodamine B can still reach 94.3%after repeated use 10 times of FNGA,indicated good stability of FNGA.?3?Polyimide?PI?/photo-Fenton?PF?In this experiment,a modified PF system was formed with mercury and tungsten mixed lamp as the light,polyimide?PI?as photocatalyst and ferrous sulfate as iron source.Polyimide?PI?was prepared by solid heat sintering method.The characterization of the material indicated that the polyimide reaction had been completed and PI has good morphology and structure.Rhodamine B was applied as pollutant,after one hour of degradation,the degradation rate was 62.8%in PI/PF,which exceeded 31.9%of traditional photocatalyst g-C₃N₄.The cumulative amount of hydrogen peroxide in the PI/PF system was 114 mg/L after an hour,while in the g-C₃N₄/PF system was 83 mg/L.