Study On Chemiluminescence Characteristics And Degradation Application Of Potassium Ferrate

Potassium ferrate?K₂FeO₄?is an environmentally friendly oxidant.It not only has strong oxidizing properties,but also will not cause extra pollution to the environment during the use.K₂FeO₄ possesses superior comprehensive performance than traditional chlorine-containing oxidants,and is widely used in water purification and organic synthesis.Although potassium ferrate has high stability in the condition without water,which can be stored for a long time.However,when dissolved in aqueous solution,it will undergo an oxidation-reduction reaction with water.The stability will be greatly reduced,and the actual concentration is lower than the theoretical concentration.Therefore,it is of great significance to study the stability of K₂FeO₄in aqueous solution.K₂FeO₄ not only has stronger oxidizability than potassium permanganate?KMnO₄?,but also has better chemiluminescence?CL?property,which has good application prospect in the quantitative analysis of different organic and inorganic substances.In the detection of different organic and inorganic substances.CL mechanism can be revealed by comparing K₂FeO₄ CL system with KMnO₄ system.Then comprehend the understanding of the CL mechanism.In view of the current shortage of water resources and serious water pollution in China,it is of great value for our country to explore the best way to use K₂FeO₄ in degrading dye wastewater,paint wastewater and other fields.In this paper,the stability of K₂FeO₄ in aqueous solution,the chemiluminescence characteristics of K₂FeO₄,and the application of K₂FeO₄ in degrading wastewater were studied.The main contents include the following three parts:1.After K₂FeO₄ was dissolved in aqueous solution of sodium hydroxide and sulfuric acid,respectively,the UV-Vis absorption spectrum of different solution was recorded.We summarized the change of the valence state of the iron element,and analyzed the stability of K₂FeO₄ in different conditions in combination with the change of characteristic absorption peak.Other factors affecting the stability of K₂FeO₄ solution were also explored,including the original concentration of K₂FeO₄,light,temperature,additives,etc.Research have shown that K₂FeO₄ dissolved in sodium hydroxide solution mainly exists in the form of free ferrate(FeO₄^2-),with a characteristic absorption peak at 505 nm,and gradually decomposes into tetravalent iron and pentavalent iron,which is eventually reduced to trivalent iron.In sulfuric acid solution,it mainly exists in the form of protonated ferrate.The characteristic absorption peak is at 525 nm,which can be stable for a long time.However,when the acidity is too high,ferrate directly decomposes to ferric iron.When the concentration of sulfuric acid is 0.05 mol/L and the original concentration of K₂FeO₄ is 64 mmol/L,the solution of protonated ferrate is most stable.Studies on light,temperature,and additives show that lower temperature and darker environment are more conducive to the stability of K₂FeO₄ solution.Potassium chloride?KCl?and sodium chloride?NaCl?have a better stabilizing effect on the solution.2.The CL characteristics of K₂FeO₄ were studied in detail.By comparing with the KMnO₄CL system and sodium hypochlorite?NaClO?-hydrogen peroxide?H₂O₂?CL system,the reaction mechanism of K₂FeO₄ CL system was proposed.Based on its excellent luminescence properties,the application of K₂FeO₄ CL system in quantitative analysis was initially explored.Studies have shown that K₂FeO₄ can oxidize different organic substances?aliphatic alcohol,dopamine,glucose,L-ascorbic acid,etc.?and inorganic substances?sodium nitrite,ammonium sulfate,etc.?under acidic conditions,and produce obvious CL signals.Mechanism research shows that K₂FeO₄ will produce singlet oxygen?excited oxygen?during the reaction with the reducing agent under acidic conditions,then the singlet oxygen rapidly transfers to triplet oxygen?ground oxygen?,with different emission peaks around 1268 nm and 600?700 nm.K₂FeO₄ can react with L-ascorbic acid,ethanol,formaldehyde,dopamine and acetaminophen respectively,and the CL intensity show a good linear relationship with the concetration of different reducing agents.This method has the advantages of wide linear range,low detection limit and high sensitivity,which has great application potential in quantitative analysis of drug and organic pollutants in wastewater.3.The oxidative degradation of K₂FeO₄ on dye wastewater?methyl orange,crystal violet?and automotive paint wastewater was studied.By exploring the effect of potassium ferrate addition,initial pH,reaction time,etc.on the degradation effect,the best degradation conditions for different types of wastewater were obtained.Then we Studies have shown that when the concentration of methyl orange is 50 mg/L,the concentration of K₂FeO₄ is 100 mg/L,and the initial pH is 3.0,the degradation rate of methyl orange reaches 69.82%after 30 minutes.When the concentration of crystal violet is 20 mg/L,the concentration ratio of K₂FeO₄ to crystal violet is 5 to 1,and the initial pH is 9.0,the degradation rate of crystal violet is 92.13%after 60minutes.In addition,K₂FeO₄ also has a good decolorization and degradation effect on paint wastewater.When 0.08 g K₂FeO₄ is added to 20 mL of paint wastewater diluent,and the initial pH is adjusted to 9.0,the solution can be cleared after 18 hours,with the COD degradation rate is 76.19%.When 0.04 g K₂FeO₄ and 0.03 g polyferric sulfate?PFS?are used together,the solution will be clear after 30 minutes,with the COD degradation rate is 82.61%.The combined use of K₂FeO₄ with PFS to treat paint wastewater can greatly shorten the processing time,reduce the amount of K₂FeO₄,improve the decolorization effect,and there is no need to adjust the pH of the system in advance.This research has certain guiding significance for the treatment of dye wastewater and paint wastewater in the actual practice.