Preparation And Application Of Sodium Carboxymethyl Cellulose Fe₃O₄ Fenton-like Catalyst

With the rapid development of dye industrialization,the varieties of dyes are increasing day by day,of which,azo dyes are mostly used.Azo dyes are widely used in papermaking,printing and dyeing,textile,paint,leather,rubber,ink and other industries,therefore,the larger the wastewater discharge,accounting for 1/10 of the total emissions of industrial wastewater,is now recognized as the major source of environmental pollution one.However,the azo dye wastewater is prone to reduce the reaction to produce carcinogenic aromatic amine compounds.In addition,the azo dye wastewater has the disadvantages of complex components,difficult degradation,high toxicity,high chroma,difficult decolorization and high COD.This not only severely damaged the ecological environment,but also caused serious threats to the sustainable development of human society.Fenton technology,one of advanced oxidation processes,with its efficient reaction rate,complete oxidation and ease of operation and other advantages in the field of water treatment more and more attention and practical applications,but the traditional Fenton technology in the treatment of organic pollution in practical applications,it is difficult to avoid these disadvantages such as large amount of iron mud,difficult removal of iron flocs,excessive consumption of oxidant and waste of catalyst,so it is urgent to reform the traditional Fenton technology and develop a new Fenton system to make it.It not only has the functions of strong oxidation and high efficiency of Fenton method,but also avoids the main defects of the above traditional Fenton technology.In this study,based on the complexation reaction between organic ligands and metal ions on the surface of heterogeneous catalysts,the physical and chemical properties of Fe₃O₄ surface were changed by coating the nanoparticles with organic ligand sodium carboxymethyl cellulose?CMCNa?Fe₃O₄ catalytic performance.Firstly,Fe₃O₄ nanoparticles were synthesized by coprecipitation,and then Fe₃O₄ nanoparticles were prepared by coating Fe₃O₄ in different concentrations of sodium carboxymethyl cellulose solution to obtain Fe₃O₄/CMC nanocomposites of No.1,No.2 and No.3.The obtained product was analyzed by Fourier transform infrared spectroscopy?FT-IR?,X-ray diffraction?XRD?,scanning electron microscopy?SEM?and other instruments to determine the structure and composition of the product,and confirmed the CMCNa Successfully coated iron oxide nanoparticles,CMCNa with a large number of carboxyl groups,there is a certain electrostatic repulsion,can inhibit the agglomeration of Fe₃O₄ nanoparticles,making the new preparation of Fe₃O₄/CMC nano-catalyst not only has good magnetic properties,but also has good dispersion performance.Fenton-mediated oxidative degradation of Acid Scarlet GR with Fe₃O₄/CMC nanocatalyst was studied.The effect of catalyst dosage,initial concentration of Acid Scarlet GR solution,pH and H₂O₂ dosage on the reaction results was discussed by single factor experiments.The results showed that the degradation rate of acid red GR decreased with the increase of the initial pH of the solution.Under the same reaction conditions,the heterogeneous Fenton reaction of Fe₃O₄/CMC nanocatalyst was superior to the degradation rate of acid red GR of azo dyes Fe₃O₄nano-catalyst heterogeneous Fenton reaction and H₂O₂ alone oxidation,and also under the conditions of pH=3.5,Fe₃O₄/CMC nano-catalyst heterogeneous Fenton advanced oxidation degradation rate was as high as 98%.The oxidative degradation mechanism of Acid Scarlet GR was studied in this research.By electron spin resonance spectroscopy,the test showed that Fe₃O₄/CMC nano-catalyst to generate free hydroxyl free radicals H₂O₂.Hydroxyl radicals have a strong oxidative,oxidative degradation of Acid Scarlet GR into non-hazardous water and carbon dioxide molecules.After that,the oxidative degradation process of Acid Scarlet GR was analyzed,which showed that the functional groups such as benzene ring,azo group,sulfonic acid group and naphthol were broken.In this paper,Fe₃O₄/CMC nanocomposites were coated with organic ligands to form Fenton-like catalytic oxidation system,which could decompose the refractory substances in organic wastewater into small molecules such as H₂O and CO₂,and had a wide pH range of use,recyclable,will not cause secondary pollution,the advantages of efficient degradation of dye contaminants.This research not only broadens the application of Fe₃O₄/CMC catalyst to wastewater treatment,but also plays an important role in organic wastewater treatment and environmental control.